Up-hole pump-in core barrel apparatus

BACKGROUND OF THE INVENTION

This invention relates to drilling apparatus and more particularly to mechanism for minimizing the chances of undesired movement of the latches of an underground core barrel inner tube assembly from their latch seated position when the drilling direction is at a hole angle that is above the horizontal prior to mechanically retracting the latch retractor tube.

In at least some prior art underground core barrel inner tube assemblies, there is undesired unlatching in certain situations despite provisions and operational training to avoid such situations. This is primarily due to the pump-in seal being mounted to the latch retracting tube. The latch spring acting between the latches may be overcome and the latches sufficiently retracted when a negative pressure occurs on the “drill side” of the seal due to removal of the water supply at the outer end of the drill string or when a positive pressure occurs on the bit side of the seal due pressurized in-ground water acting to urge the latch retractor tube toward its latch retracting position. Further, the significant mass of the spear head base, seal bypass valving and latch retractor tube can develop sufficient inertia to overcome the latch spring and retract the latches as a result of jerking of the drill string or extreme drilling vibration. With undesired unlatching and the drilling direction being sufficiently great above the horizontal, the core barrel inner tube assembly can move axially outwardly with sufficient force to damage the apparatus at the drilling surface end of the drill string and/or injure drilling personnel.

In U.S. Pat. No. 6,029,758 to Novacovicci et al there is disclosed a retractable core barrel inner tube assembly that includes a drilling apparatus head assembly having valving mechanism to substantially restrict or block fluid flow through its fluid bypass channel, together with being movable to maintain a desired fluid hear in the drill string, and thereafter, being mechanically retractable to an axially outer open position in the fluid bypass channel as the head assembly is retracted in the drill string prior to the latch body being retracted.

U.S. Pat. No. 5,339,915 to Laporte et al discloses a one way retention valve in a core barrel inner tube assembly that functions to retain drilling liquid pressure in lost circulation situations resulting from, for example, drilling into a cavity or into a broken earth formation. Further, a heavy duty spring is used to create a high liquid pressure and retain a column of liquid above the core barrel inner tube assembly.

U.S. Pat. No. 3,333,647 to Karich et al discloses a core barrel inner tube assembly having spring mechanism acting between a latch body and a latch release tube to constantly urge the latch release tube to a position permitting the latches moving to a latch seated position.

In order to make improvements in underground core barrel inner tube assemblies to minimize undesired unlatching of an underground inner tube assembly in up-hole drilling (a drilling direction above the horizontal, this invention has been made.

SUMMARY OF THE INVENTION

A drilling assembly that is movable in a drill string to the inner end portion thereof for being latchingly retained therein includes a latch body having latch retracting mechanism mounted thereon for limited axial movement relative thereto for retracting the latches of the latch assembly from a latch seated position. The latch body is of a three part construction with each latch body part defining a part of a fluid bypass channel with the intermediate part being removable from the other two parts and having a seal member thereon to form a fluid seal between the latch body and the drill string. Spring mechanism acts between the latch body and the latch mechanism to constantly urge the latch mechanism to its latch seated position. A drilling tool is attached to the latch body to extend inwardly thereof, the tool being any one of, for example, a core barrel inner tube, a plug bit, an earth sampling tube and etc.

One of the objects of this invention is to provide new and novel means in up-hole drilling apparatus that is latchingly coupleable in a drill string for rendering a safety feature to minimize the chances of accidental unlatchingly coupling from a drill string during up-hole drilling operations. Another object of this invention is to provide in a drill head assembly, a new and novel latch body assembly that may be readily converted between one primarily for underground (up-hole) use and one primarily for down-hole use.

For purposes of facilitating the description of the invention, the term “inner” refers to that portion of the drill string, or of the assembly, or an element of the assembly being described when, in its position “for use” in, or on, the drill string is located closer to the drill bit on the drill string (or bottom of the hole being drilled) than any other portion of the apparatus being described, except where the term clearly refers to a transverse circumferential, direction, or diameter of the drill string or other apparatus being described. The term “outer” refers to that portion of the drill string, or of the assembly, or an element of the assembly being described when, in its position “for use” in, or on, the drill string is located axially more remote from the drill bit on the drill string (or bottom of the hole being drilled) than any other portion of the apparatus being described, except where the term clearly refers to a transverse circumferential, direction, or diameter of the drill string or other apparatus being described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A

,

1

B,

1

C and

1

D when arranged one above the other with their axial center lines aligned and lines A—A and B—B of

FIGS. 1B and 1B

aligned, lines E—E and F—F of

FIGS. 1B and 1C

aligned and lines G—G and H—H of

FIGS. 1C and 1D

aligned, form a composite longitudinal section through the drilling apparatus of the first embodiment of this invention with the core barrel inner tube assembly seating on the drill string landing ring; said view being generally taken along the line and in the direction of the arrows

1

A,

1

B-

1

A,

1

B of

FIG. 2

with axial intermediate portions broken away;

FIG. 2

is an enlarged, fragmentary longitudinal sectional view of the first embodiment with the landing indication valve assembly ball portion having been inwardly forced partially through the adjacent bushing;

FIG. 3

is an enlarged, fragmentary longitudinal view of the latch body portion of the first embodiment in which the liquid retention valve assembly is mounted, said valve assembly not being shown; and

FIG. 4

is a longitudinal cross sectional view of the inner end portion of a second embodiment of the invention which shows a drag bit.

DETAILED DESCRIPTION OF THE INVENTION

Referring now in particular to

FIGS. 1A

,

1

B and

1

C, there is illustrated a hollow drill string

10

which is made up of a series of interconnected hollow drill rods (tubes). Even through the drilling direction is not shown as being upwardly, the drill string

10

is in an upwardly extending bore hole

12

drilled in rock or other types of earth formations by means of an annular core bit

11

which is at a higher elevation than the axial outer end of the drill string. The pump apparatus located at the drilling surface and indicated by block

84

pumps fluid under pressure through line

88

into the outer end of the drill string

10

in a conventional manner. The bit in the bore hole

12

may be at a considerable elevation above the drilling surface but at a considerable depth below the earth surface.

The portion of the drill string attached to or extended below the pipe (rod) section

10

A is commonly referred to as a core barrel outer tube assembly, generally designated

13

, the core barrel outer tube assembly being provided for receiving and retaining the core barrel inner tube assembly, generally designated

15

, adjacent to the bit end of the drill string. Details of the construction of the core barrel outer tube assembly used in this invention may be of the general nature such as that disclosed in U.S. Pat. Nos. 3,120,282 and 3,120,283. The outer tube assembly is composed of an adaptor coupling

21

that is threadedly connected to the core barrel outer tube

18

to provide a recess in which a drill string landing ring (drill string landing shoulder)

27

is mounted. A reaming shell

19

is joined to the inner end of tube

18

with an annular drill bit

11

at the inner end of the reaming shell for drilling into the earth formation from which the core sample is taken. The outer end of the assembly

13

includes a locking coupling

20

that connects the adaptor coupling

21

to the adjacent pipe section

10

A of the drill string. At the opposite end of the coupling

20

from the pipe section

10

A, the locking coupling, in conjunction with the annular recess of the adaptor coupling

21

, form a latch seat

21

A inside of the surface of the adaptor coupling against which the latches

47

,

48

of the latch assembly L are seatable for removably retaining the core barrel inner tube assembly

15

adjacent to the core bit. The inner end portion of the locking coupling may have a conventional projection flange (not shown) to bear against a latch to cause the latches and other portions of the inner tube assembly to rotate with the drill string when the latches are in a latched position, as is conventional.

The assembly

15

includes a core receiving tube

31

, an inner tube cap

33

threaded to the outer end of the core receiving tube and a spindle and bearing subassembly, generally designated

41

, connecting the cap to the inner portion

46

of the latch body. The subassembly

41

includes a spindle bolt

41

A threadedly connected to the inner body portion of the latch body, and connects the cap to the latch body for limited movement in a conventional manner. The subassembly

41

also includes bearing mechanism

76

axially slidably on the spindle bolt, the mechanism including a bearing member threaded to the inner tube cap. Conventional shut-off valve mechanism

78

is provided on the spindle bolt between the bearing mechanism and a spindle bolt enlarged diametric portion to have its resilient members

78

A expand in girth as they are compressed to form a fluid seal with the inner periphery of the drill string when the core receiving tube is filled or there is core blockage to provide a high pressure fluid signal as is conventional.

The core receiving tube has a replaceable core lifter case

34

and a core lifter

35

, the structure and function of which may be generally the same as set forth in U.S. Pat. No 2,829,868. A fluid passageway

39

formed in the cap

33

opens through a valve subassembly

38

to the interior of the outer end of the core receiving tube and at the opposite end to the annular clearance space

37

between the inner tube assembly and the outer tube

18

that forms a part of the annular fluid channel

37

to, in conjunction with the latch body bypass channel F, permit fluid to bypass the inner tube assembly when in a core taking position. The structure of, the function of and the manner of the mounting of the spindle-bearing subassembly may be very similar to that described in greater detail in U.S. Pat. No. 3,305,033.

The core barrel inner tube assembly

15

also includes a latch body, generally designated

25

, having a main body portion

44

, the inner body portion

46

and an axial intermediate, annular adaptor subassembly M threadedly connecting the adjacent ends of the main body and inner body portions to one another. The adaptor subassembly includes an axial inner adaptor part

45

which has an enlarged diametric flange

45

A and an axial inner, reduced outer diameter part

45

B extended into and threadedly connected to the inner body portion axial outer part

46

E to cooperatively provide a radially outward annular groove to removably mount a latch body ring

24

which is of a larger outer diameter than any other part of the latch body. Thus, the latch body ring provides a latch body shoulder that is seatable on the drill string shoulder (landing ring)

27

, the landing ring

24

and flange

45

A and the enlarged diametric portion

46

E of the adaptor subassembly cooperatively providing a maximum enlarged diameter latch body portion. It is to be understood that in place of a landing ring

27

, the axial outer part of adaptor part

46

may be of a larger outer diameter such as of the outer diameter of the landing ring

24

to provide a latch body landing shoulder seatable on the drill string landing shoulder.

Referring to

FIG. 2

, the reduced outer diameter, axial inner end portion

44

A of the main body portion

44

is threaded into the axial outer annular portion

43

A of the adaptor outer part, portion

43

A being of an inner diameter that is greater than the inner diameter of the adjacent intermediate annular portion

43

E of the adaptor outer part. Portion

43

E is of a greater inner diameter than the diameter of the axially adjacent annular portion

43

C to which it opens. Part

44

A and portions

43

C and

43

E cooperatively providing a radially inwardly opening groove in which a bushing

49

is mounted.

The latch body portions

43

,

44

,

45

and

46

cooperatively provide a fluid bypass channel F that includes inlet ports

52

in main body portion

44

that opens to an axial bore (chamber)

57

inwardly of the bore outer end and outwardly of the enlarged diameter flange

44

C of the main body portion

44

, and outlet ports

53

in the inner body portion that open to the bore

57

axially inwardly of a bushing

49

. The fluid bypass channel F permits fluid flow to bypass the drill string landing ring

27

and the latch body ring

24

when the ring

24

is seated on the ring

27

. That is, other than for the fluid seals

28

, the portions of the inner tube assembly from the latch body ring

24

axially inwardly and outwardly are of smaller maximum diameters than the maximum outer diameter of the ring (latch body shoulder)

24

while the bypass channel has ports

52

opening exterior of the latch body axially outwardly of the ring

24

to the annular clearance space outwardly of the ring

24

and radially between the latch body and the drill string and second ports

53

opening exterior to the annular clearance space axially inwardly of the ring

24

and radially between the latch body and the drill string. The latch body landing ring, when seating on the drill string landing ring, blocks or severely restricts axial inward flow therebetween. The bushing

49

constitutes part of a two way liquid landing indicator valve mechanism, generally designated

40

, for controlling fluid flow through the latch body fluid bypass channel F and providing a high pressure signal at the drilling surface when the latch body landing ring has seated on the drill string landing ring and the latches have moved to their latch seated position. The bushing is mounted in an axially intermediate diameter portion

57

X of the bore

57

which is formed in the adaptor outer part

43

to abut against a transverse outwardly facing annular shoulder of adaptor portion

43

C with the bushing being located axially intermediate of the opening of the ports

52

and

53

to bore

57

. Except for the minimum diameter of a bushing

50

, the minimum diameter (axial intermediate cylindrical surface portion

49

B) of the bushing

49

, when mounted in bore

57

, is substantially smaller than any portion of the bore

57

axially intermediate the openings of the inlet and outlet ports to bore

57

. The bushing

49

has an axial outer frustoconical portion

49

A and an axial inner frustoconical portion with the minimum diameter cylindrical portion

49

B extending therebetween.

The valve mechanism

40

also includes valving assembly V that comprises a valve ball member

99

. The valve ball member

99

is axially movable in the bore

57

and has an inner ball portion

99

A which is partially spherical with a transverse maximum diameter section that is of a diameter slightly less than the minimum diameter of the bushing cylindrical surface portion

49

B if the bushing is made of metal, but may be greater than the minimum diameter of portion

49

B if the bushing is made of a resilient material. In either event, the maximum transverse diameter section of the ball member is such that said section is movable axially inwardly through at least the minimum diameter portion

49

B of the bushing and, when in the minimum diameter portion, blocks or substantially restricts fluid flow through the bypass channel.

The outwardly extending non-spherical part of the ball portion of the valve ball member is threadedly mounted to a valve stem (shaft)

102

. The valve stem is axially slidably extended and rotatable in an axial bore

101

in the transverse, generally cylindrical stem mount

104

, bore portions

101

A,

101

B forming an outwardly facing shoulder to have the enlarged head portion

102

A of the valve stem abut thereagainst for limiting the inward axial movement of the valve stem relative to the stem mount. The stem mount is mounted in a fixed axial position to and within the inner end portion of the latch retractor (tube)

54

by screws

103

to move axially therewith.

As the latch retractor

54

is moved to its maximum axial outer position relative to the latch body, the ball portion

99

is moved to a valve open first position axially outwardly of the bushing

49

to permit maximum fluid flow through the bushing. When the latches are in abutting relationship to the drill string as the core barrel inner tube assembly moves inwardly in the drill string the latches are retained in a position pivotally intermediate their latch seated and latch retracted positions. With the latches being retained in their intermediate position, the latch retractor is prevented from moving to an axial inner position relative to the latch body and is retrained in a position relative to the latch body axially intermediate its maximum and minimum axial positions relative to the latch body as a result of pin

58

being prevented from moving further inwardly relative to the latch body until the latches move to their latch seated position. With the latches and latch retractor in their intermediate position, the ball portion

99

has moved to and retained in an axial inner valve second position to have its maximum diametric section radially aligned with bushing portion

49

B to restrict or block inward fluid flow through the bushing. When the latch body landing ring has seated on the drill string landing ring, both of the latches moved to their latch seated position and the latch retractor abuts against the latch body flange

44

C, the ball portion

99

is movable under fluid pressure to a valve open third position to have its transverse maximum diametric section inwardly of the bushing portion

49

B to permit increased fluid flow through the bypass channel, provided fluid is under sufficiently high inward pressure to move the valve ball

70

inwardly out of engagement with the bushing

50

.

The stem mount axially movably extends through the main body portion stem mount slot

107

with either the slot

107

and/or the movement of a retractor pin

58

in a latch body retractor pin slot

77

limiting the axial movement of the stem mount relative to the latch body. The slot

107

opens to the axial outer bore portion

57

A of bore

57

axially inwardly of the outer end of the bore portion

57

A (see

FIG. 2

) with at least the major part of the stem mount being movable outwardly of the opening of the ports

52

to bore portion

57

A to decrease the resistance to axial inward fluid flow through the bypass channel. Bore portion

57

A is formed in the main body portion of the latch body with the diameter of the stem mount being substantially less than the maximum transverse dimension of the bore portion

57

A. The stem mount, valve stem and the adjacent parts of fluid bypass channel may be the same or similar to that set forth in U.S. Pat. No. 6,029,758 whereby the fluid flow through the bypass channel F is not significantly reduced by the valving assembly V when the latch retractor is in its axial outer position relative to the latch body.

Axially inwardly of the opening of the ports

53

to bore

57

, the inner body portion

46

has a minimum diameter bore portion

46

F to provide an annular, axially outwardly facing shoulder against which is seated the inner end of a coil spring

70

that is part of the liquid retention valve subassembly T. The opposite end of the spring constantly resiliently urges the valve ball

71

against the axial inner frustoconical valve seat

50

C of the bushing

50

to block axial outward fluid flow through the bushing. The bushing

50

has an axial intermediate, minimum diameter cylindrical portion

50

B and an axial outer frustoconical portion

50

A. Advantageously the bushing

49

and

50

are of the same shape and size with bushing

50

being made of metal to prevent the valve ball

71

being movable axially therethrough.

The bushing

50

is seated in a radially inwardly opening annular groove defined by the inner body portion reduced diameter part

46

C which is axially outwardly adjacent to the opening of the ports

53

to the bore

57

, the annular surface of part

46

E that extends between part

46

C and outer adaptor part

45

B, and the transverse inner surface of part

45

B. The valve ball

71

is of a smaller diameter than the inner diameter of part

46

C so that it can be inserted into the bore

57

before the bushing

50

is mounted in bore

57

. The bushing

50

is located in the bore

57

axially inwardly of bushing

49

.

The axial outer, annular portion

45

E of the axial inner adaptor part

45

is of a reduced outer diameter and of an axial length to have its outer end threaded into adaptor outer part

43

and to mount resilient fluid seals members

28

to abut against the inner transverse surface of the outer adaptor part

43

and portion

45

A of the inner adaptor part. Each of the seal members

28

includes a radial inner, axially elongated annular portion

28

A bearing against the outer peripheral surface of portion

45

E of the inner adaptor part

45

and a web

28

B joined to the axial inner end portion of the radial inner portion

28

A and to the inner end portion of the radial outer, axially elongated annular portion

28

C to provide an axially outwardly opening annulus between portions

28

A,

28

C. Portion

28

C has an outer peripheral cylindrical portion surface to at least substantially form a fluid sealing fit with the inner peripheral wall of the drill string as the inner tube assembly moves axially inwardly in the drill string. Advantageously, the fluid seals

28

are of a construction the same as or similar to the seal member of the overshot assembly of U.S. Pat. No. 5,934,393 that forms a fluid seal with the drill string and thus will not be further described. The fluid seals

28

block fluid flow bypassing the inner tube assembly through the clearance space between the inner tube assembly and the inner peripheral wall of the drill string, but permits fluid bypassing the inner tube assembly through the bypass channel F when valve assemblies V and T are out of fluid blocking positions with bushings

49

and

50

respectively.

When the latches are in a latch seated position with the retractor transverse inner edge

54

A abutting against annular flange

44

C, the retractor has notches

108

that open inwardly through the inner edge

54

A and extend outwardly the same distance that radially adjacent ports

52

extend to form part of the fluid bypass channel F when the core barrel inner tube assembly is in a core taking position, see FIG.

2

. Advantageously, the parallel axial extending edges of the notches are of a spacing about the same as the diameter of the ports

52

.

The core barrel inner tube assembly also includes a latch assembly L having the pair of latches

47

,

48

with their axial inner end portions pivotally mounted in a latch body slot

25

A by a pivot member

51

that is mounted to the latch body. The pin

58

mounts the latch retractor (release tube)

54

to the latch body for limited axial movement relative thereto for retracting the latch assembly from its latch seated position to its latch release position and alternately permitting the latch assembly moving to its latch seated position when the latches are radially adjacent to the latch seat.

The latch assembly L also includes a toggle linkage subassembly having generally transversely elongated toggle link members that include toggle links

75

,

78

pivotally mounted by pivot link pins to the axial outer ends of portions of the latches

47

,

48

respectively for pivotal movement of the latches between a latch retracted position and an extended latch seated position of

FIG. 1A

(or an overcentered locked position, for example such as shown in the above mentioned patent to Harrison). The horizontally extending retractor pin

58

extends transversely through link apertures in the adjacent ends of the links and the axially elongated slot

77

of the latch body. The opposite ends of the pin

58

are mounted in fixed axial relationship to the latch retractor and form a lost motion pivotal connection between the latch body, the latches and the latch retractor tube

54

. The axial outward movement of the latch retractor tube relative to the latch body is limited by the pin

58

abutting against the outer edges of the latch body that in part define slots

77

and the axial inward movement is limited by one of the pin

58

abutting against the axial inner edges of the slots

77

and the annular, axial inner edge portion

54

A of the latch retractor tube abutting against the annular flange

44

C. The pin

58

retracts the latch body when the pin

58

abuts against the outer ends of the slots

77

and is moved axially outwardly.

A spring mount comprising an annular member

117

and a fastener (bolt)

114

threadedly connected to the main body portion

44

retain the annular member

117

in abutting relationship to the axial outer transverse surface of the latch body main portion

44

. An axially extending coil spring

118

is provided on the axial outer part of the main body portion to have one end abut against the annular member

117

and its opposite end abut against the pin

58

, and may abut against the toggle links

75

,

78

, to constantly resiliently urge the pin axially inwardly and thereby the latch retractor tube and the latches toward their latch seated positions with at least one of the retractor pin

58

abutting against the axial inner edge of the latch body slots

77

and the axial inner terminal edge portion

54

A of the latch retractor abutting against the shoulder

81

of the enlarged diametric portion

44

C of the main body portion

44

.

A pin

55

is fixedly mounted to the outer end portion of the latch retractor tube and is extended through an axially elongated slot

72

in the plug

73

of the overshot coupling device, generally designated

59

. Thus, the plug

73

may be moved relative to the latch retractor to an axial inner position and an axial outer position for retracting the latch retractor. The device

59

includes a spear point

74

that is joined to the plug

73

. Even though the overshot coupling device

59

shown may be of substantially the same construction as that described in U.S. Pat. No. 4,281,725 and function in the same manner, it is to be understood that other overshot coupling devices can be used.

When the core barrel inner tube assembly is in its core taking position of

FIGS. 1A and 1B

with the latches in their latch seated position, the inner annular edge

54

A of the latch retractor tube abuts against the axially outwardly facing shoulder

81

of the annular flange

44

C. The latches are extendable radially outwardly through the retractor tube slots

83

and the axial inner ends of slots

83

may or may not abut against latches to retract the latches from their latch seated position as the retractor tube is retracted. Advantageously, the slots

83

may be angularly spaced relative to the slots

108

.

The second embodiment of the invention (see FIG.

4

), generally designated

93

, includes a latch body, a latch assembly, valving mechanism and latch retracting mechanism that may be the same as that disclosed with reference to

FIGS. 1A

,

1

B and

2

. However, instead of the spindle subassembly

41

, there is provided a conventional earth sampler spindle

87

that at its outer end is threadedly connected to the inner body portion

46

of the latch body and at its inner end is threadedly connected to a drag bit mounting sub

89

. The sub

89

threadedly mounts a drag bit

95

to extend through and inwardly of the drill bit

11

. The sub is of a type that rotates the drag bit when the bit

11

is rotated.

As may be apparent from the above description, the latch body, latch assembly, valve mechanism and the latch retracting mechanism, including the overshot coupling device provide a head assembly that may be attached to a variety of drilling tools or devices that are to be inserted in a drill string and removably latched to the inner end portion of the drill sting.

In using the apparatus of this invention in, for example, up-hole drilling, the core barrel inner tube assembly of either the first or second embodiment is inserted into the outer end of the drill string and as fluid under pressure is pumped in the drill string, the assembly moves axially inwardly. As fluid under pressure flows inwardly and the spring

118

acting against pin

58

, the overshot coupling device and latch retractor are forced inwardly relative to the latch body, but the latches are prevented from moving to their latch seated position of

FIG. 1A

as a result of the latches abutting against the inner periphery of the drill string which limits the inward movement of the pin

58

in the latch body slots

77

to a position the maximum transverse diameter part of the ball portion

99

is located in the minimum diameter part

49

B of the bushing

49

. At this time, the pin

58

prevents the inner transverse edge of the latch retractor abutting against flange

44

C.

Upon the latch body landing ring

24

seating on the drill string landing ring, the inward movement of the inner tube assembly is stopped and, with the latches opposite the latch seat

21

A, spring

118

forces the latches to move to their latch seated position and the retractor tube moves inwardly relative to the latch body to abut against flange

44

C. Since the maximum diametric section of ball member

99

is located in the minimum diameter portion of bushing

49

to substantially restrict inward fluid flow (block or limit inward flow to leakage flow) through the bypass channel and/or the landing ring

24

seating on ring

27

and/or spring

70

retaining ball

71

against valve seat

50

C, the fluid pressure at the drilling surface builds up to provide a high pressure signal to indicate the inner tube assembly is in a position for taking a core. It is noted that at this time the enlarged diametric portion

102

A is axially outwardly of the juncture of bore portions

101

A and

101

B.

In the event one of the latches does not move to its latch seated position, pin

58

and the latch retractor are prevented from moving inwardly relative to the latch body sufficiently that the maximum transverse diameter section of ball member

99

can move inwardly of the bushing portion

49

B. Accordingly, any significant fluid flow through the fluid bypass channel is blocked even though the latch body has seated on the drill string landing ring.

With the latches in their latch seated position, upon increasing the pump-in fluid pressure, or if the pump-in pressure is sufficiently high, the fluid force acting on the valving assembly V forces ball member

99

inwardly to have the ball member maximum transverse diametric section sufficiently inwardly of the bushing portion

49

B to be radially opposite or inwardly of the bushing inner frustoconical portion to increase the annular clearance space between the ball member and bushing

49

, together with forcing the valve ball

71

inwardly relative to bushing portion

50

C to permit axial inward fluid flow through the bypass channel. Thus, the annular clearance space between the ball portion

99

A and the bushing

49

and the annular clearance space between frustoconical surface

50

C and ball

71

increase with increasing pump-in fluid pressure to permit increased rate of fluid flow through the bushings and thereby increased axial inward flow through the bypass channel F. Once the ball member

99

moves inwardly to its full valve open position with valve stem portion

102

A abutting against the shoulder defined by bore portions

101

A,

101

B, it remains in its open position until retracted as a result of the retraction of the latch retractor.

Advantageously, the characteristics of spring

70

are such that the fluid force required to force the valve ball out of engagement with the bushing

50

is much greater than the force required to force the maximum transverse diameter section of ball member

99

inwardly of the minimum diameter portion

49

B of the bushing

50

. In many core drilling operations it is desirable to have a very high drilling pressure and as a result a spring

70

is used whereby a very high fluid pressure is required to move the ball inwardly of the valve seat

50

C. With the spring

70

acting against the valve ball, fluid flow outwardly through the ports

53

to the bore

57

(back pressure) is blocked and such back pressure acting against the fluid seals

28

together with that acting against the latch body does not result in the inner tube assembly moving axially outwardly since the back pressure does not act against the latch retractor to move to its latch retracting position and the spring

118

acting against the latches retains them in their latch seated position to prevent the latch body moving axially outwardly.

When, because of a core jam in the inner tube or the desired length of core has been taken, the core drilling is stopped together with retracting the drill string sufficiently to break the core from the earth formation, the pumping in of drilling fluid is discontinued and a conventional underground overshot assembly (not shown) is inserted into the drill string and pumped in to move to couplingly engage the overshot coupling device

59

. As one example, the overshot may be of a construction such as set forth in U.S. Pat. No. 3,120,283. If the pumping in of fluid is discontinued or the pump-in pressure is decreased, the spring

70

moves the bali

71

outwardly or retains it in a position to block axial outward fluid flow through the bushing

50

and in the bore

57

to bushing

49

.

The initial retraction of the overshot coupling device acts to apply a retraction force to pin

55

, if not already applying such a force, to retract pin

55

. The retraction of pin

55

retracts the latch retractor which moves the stem mount

104

outwardly to retract the ball member

99

and pull it through the bushing

49

to have its maximum transverse diameter section axially outwardly of the axial outer frustoconical portion

49

A of bushing

49

. As the transverse maximum diameter section of the ball member

99

is moved axially outwardly of bushing portion

49

B, the resistance to drilling fluid (liquid) flowing axially inwardly through the bushing

49

may be substantially decreased. Further, as the retractor tube is moved axially outwardly, either the retractor tube moves the pin

58

to act through the toggle linkage, or if such linkage is not used but with spring mechanism (not shown) urging the latches to their latch seated position, the inner edges

83

B of the latch slots

83

abut against the latches to retract the latches. Prior to the pin

58

abutting against the outer ends of latch body slots

77

, the ball member

99

has been moved sufficiently outwardly relative to the bushing

49

to, as the latch body is retracted, permit fluid flow through the bushing

49

and depending on the characteristics of spring

70

, the ball

77

being moved inwardly against the action of the spring

70

, whereby resistance to the retraction of the inner tube assembly and the latch body may be reduced if the amount of liquid to be drained out of the outer end of the drill string is to be reduced.

If desired, bushings

49

, and/or the valve ball member

99

(with unthreading of screws

103

) may be replaced by unthreading and rethreading the latch body portions

43

,

44

. By unthreading the outer adaptor part

45

from the inner adaptor part

46

, the bushing

50

and then the spring

70

and valve ball member

71

may be removed and replaced with an appropriate bushing and/or valve ball

71

and/or spring

70

to change the inward fluid pressure required to permit inward fluid flow through the bypass channel.

It is to be understood it is possible to use the core barrel inner tube assembly of each of the embodiments without one of the valve assemblies V and T, although it is desirable to use both. With the valve assembly V, if the head assembly becomes stuck in the drill string or both latches fail moving to their latch seated position, the ball member

99

remains in it closed position and pressure will continue to build until the pump's valve (not shown) blows or the pump drive stalls. Even though the head assembly of this invention can be used without valve assembly T, it provides a more complete fluid seal during pumping in the inner tube assembly, particularly when there is leakage pass the valve assembly V, whereby there is an increase in pump-in velocity. Further, with a strong spring

70

, after the valve member

99

in its inner most open position, the high drilling pressure results in a strong and faster signal being received at the drilling surface upon there being a core blockage or the core receiving being filled and the shut-off valve members expanding in girth.

The core barrel inner tube assembly of either embodiment described herein may be readily converted to one primarily for down-hole drilling by unthreading the inner and outer adaptor parts from the latch body inner and outer portions

44

,

46

, remove bushing

50

and ball

71

and possibly removing and if desired, replacing spring

70

with one for abutting against ball member

99

and thence threading main body portion

44

A into inner body portion

46

E. In such an event, an axially shorter adaptor coupling would be used. To be noted, advantageously the axial lengths of main body portion

44

A and inner adaptor portion into which portion

45

B is threaded are the same whereby the flange

44

C is abuttable against the outermost transverse surface of the inner body portion

46

. As another alternative, the adaptor parts may be unthreaded, the fluid seals

28

removed and then the adaptor parts threaded together.

Even though, as disclosed above, there is provided a single latch pivot, it is to be understood that there may be provided two latch pivots in parallel relationship with one latch being pivotally mounted by each latch pivot as long as the latch pivots and the link pivots are located such that the links and latches will move between latch seated and latch retracted positions and the spring

118

constantly urges them to a latch seated position.