Mobile carriage

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 09/101,066, filed on Jun. 29, 1998, now U.S. Pat. No. 6,161,485; which is a national stage of PCT/US96/17422 filed 10/30/96.

BACKGROUND OF THE INVENTION

This invention pertains to power transmission, and more particularly to apparatus for driving mobile storage carriages.

Mobile storage systems, for storing. books, supplies, and files are in widespread use where it is important to provide high density storage, such as in offices, schools, and libraries. My U.S. Pat. No. 5,007,351 describes an improved power transmission mechanism for use in such systems.

Typical mobile storage systems include two or more parallel rails embedded in or attached to a building floor. One or more relatively long and narrow carriages span the rails. The carriages may exceed eighty feet in length, and the number and spacing of the rails are chosen to suit the particular carriage length. The carriages are usually supported by a pair of wheels rolling along each of the rails.

The carriages may be designed to move along the rails under manual power. For that purpose, a hand wheel is usually mounted to a carriage end panel. The hand wheel is connected by various drive components to a shaft that in turn is connected with at least one of the carriage wheels. Manually rotating the hand wheel causes the drive wheels to rotate and move the carriage. Electrically powered carriages are also in wide-spread use. With that design, a suitable electric motor is substituted for the manual hand wheel. The motor shaft is mechanically connected through a suitable mechanism to the carriage drive wheels.

It has been a common practice to design mobile carriages such that drive wheels are located along the length of the carriage on one side of the carriage. These prior designs require a long shaft for connecting the drive wheels along the carriage length. The long shafts are awkward to assemble and service. In addition, the long shafts generally undergo torsional wind-up when used with heavy carriages, such that, due to twisting of the shaft along its length, the drive wheels at the carriage end remote from the electric motor or hand wheel do not rotate as fast as the drive wheels at the end at which the shaft is rotationally driven. Consequently, despite the use of flanges on the drive wheels, the carriages can tend to skew as they are driven along the rails.

In accordance with my earlier patent, a single driving mechanism was provided at the center of the carriage. However, a need has continued to exist for improved mobile storage carriages with more than one drive mechanism, but which would overcome the aforementioned skewing problem encountered with the prior art.

SUMMARY OF THE INVENTION

In accordance with the present invention, drive systems are provided which improve the performance of mobile storage system carriages and which obviate the aforementioned skewing problem.

In accordance with the invention, at least two synchronized transversely spaced drive units each engage separate rails. A single power source such as an electric motor is connected to a drive shaft that spans all of the rails on which drive units are provided. The shaft is provided with drive sprockets which are intermeshed with driven gears of the drive mechanisms. Torsional twisting of the drive shaft is minimized by use of gear ratios between these gears which provide a sufficient mechanical advantage to effectively reduce the torque applied to the drive shaft.

As in the case of my earlier invention, the drive wheels may have central flanges that fit within and are guided by a longitudinal groove in the rail top surface. Alternatively, the wheels may be flat or may be provided with flanges on each side and are adapted to travel on a flat rail. Anti-tip restraining clips may be provided to insure stability of the mobile storage system.

To drive the carriage drive wheels of each drive unit in synchronization, sprockets are provided to which power is transferred by means of a chain trained around the sprockets. The chain is driven by a drive sprocket that is attached to the drive shaft, which is in turn rotated by a power source such as an electric motor or the output shaft of a speed reducer. To provide tension adjustment to the drive chain, the drive sprocket or a separate idler sprocket is preferably made adjustable. The drive units of the present invention may also be driven by manually powered mechanisms.

Briefly, a mobile carriage system of this invention includes a pair of spaced, parallel end rails fixed to a support surface, and, usually, dependent on the length of the carriage, at least one or more intermediate rails fixed to the support surface and located parallel to and between the pair of end rails. At least one carriage is supported for movement on the end and any intermediate rails. The carriage includes an elongated frame that spans all of the rails. At least two drive units, each including a pair of wheels and supporting the carriage on a different one of the rails are provided. The drive units are operatively connected to a drive shaft which extends across a plurality of the rails. The drive shaft and each of the drive units are coupled by a drive gear on the shaft which has a first effective diameter and a driven gear on the drive unit, which has a second effective diameter substantially greater than the first effective diameter. Thus, the drive units minimize torsional twisting of the drive shaft during use. A source of rotational power such as an electric motor is operatively connected to the drive shaft.

Other features of the present invention will become apparent from the claims, detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is simplified side view of a mobile storage carriage that employs the present invention;

FIG. 2

is a cross sectional view taken along lines

2

—

2

of FIG.

1

and rotated 90° counterclockwise;

FIG. 3

a cross sectional view of another embodiment of the invention taken along lines

2

—

2

of FIG.

1

and rotated 90° counterclockwise;

FIG. 4

is a view similar to those of

FIGS. 2 and 3

showing prior art device;

FIG. 5

is an exploded partially broken perspective view of an electrically powered drive mechanism according to present invention;

FIG. 6

is a fragmentary sectional view taken along Line

6

—

6

of

FIG. 5

; and

FIGS. 7 and 8

are fragmentary sectional Views similar to that of

FIG. 6

showing alternate embodiments of the invention.

DETAILED DESCRIPTION

Referring to

FIG. 1

, a mobile storage carriage

10

is illustrated that includes the present invention. The mobile carriage

10

is typically part of a mobile storage system that includes additional mobile carriages, as well as one or more stationary storage units (not shown), as are known in the art.

The mobile carriage

10

travels along two or more parallel rails

12

spaced longitudinally along the carriage length and embedded in or attached to a building floor

9

. The carriage is supported on the rails

12

by respective pairs of wheels

11

. Power for moving the carriage along the rails may be supplied manually. In that case, the ends of the carriage are usually furnished with a hand wheel

13

. Alternately, the carriage may be designed with an electrically powered system. In that situation, the hand wheel

13

is eliminated, and a suitable electrical control, schematically represented at reference numeral

15

, is substituted.

In accordance with the present invention, electrically and manually powered mobile carriages are driven along at least two of the rails

12

a

and

12

c

by synchronized pairs of wheels wherein each pair engages a rail. Looking also at

FIG. 2

, a mobile storage system is depicted that has three rails

12

a

,

12

b

and

12

c

. The frame

17

of a carriage

10

is designed with longitudinal beams

19

and with end members

20

at opposite ends and a cross brace structural member

21

adjacent to each of the rails. At least two wheels

11

are suitably journaled in each cross brace

21

for supporting the carriage on each associated rail which is not provided with drive wheels. The mounting of the wheels to the cross braces may be by conventional components that do not form a part of the present invention.

The present invention overcomes the skewing problem illustrated in

FIG. 4

, which somewhat diagrammatically illustrates the prior art devices. In

FIG. 4

there are seen a plurality of rails R. Rails R support a mobile carriage which is supported on a frame F. Frame F is rollingly supported on rails R by means of drive wheels W. Drive wheels W are powered by a motor M using a drive shaft S. As seen in

FIG. 4

, the wheels closest to motor M are imparted with greater turning motion, thus skewing the carriage as shown. The declining amount of forward movement of the wheels W as they are spaced away from motor M is caused by the fact that a substantial amount of torque needs to be applied by motor M through drive shaft S. This amount of torque causes rotational twisting of the drive shaft S resulting in a lesser amount of rotation of the end of the drive shaft opposite the motor M.

To drive the carriage

10

along the rails

12

a

and

12

c

, the carriage frame

17

comprises a plurality, preferably two, pairs of drive wheels

23

. Referring also to

FIG. 5

, the drive wheels

23

are rotatably mounted, usually by bearings, on respective axles

25

. The axles

25

are supported between two channels

21

that span the frame longitudinal beams

19

, or by end frame

20

and a channel

21

. To each drive wheel is attached a sprocket

29

, for example, by plug welds

30

.

Trained over the sprockets

29

is a chain

31

. The chain

31

is driven by a drive sprocket

33

which is fastened to a drive shaft

35

of a combination electrical motor and speed reducer

41

. The motor and speed reducer combination

41

is mounted to the end frame member

20

by conventional fasteners. Drive sprocket

33

is of a substantially smaller effective diameter than driven sprockets

29

. Thus, a substantially lesser torsional force is developed on drive shaft

35

, relative to that of the prior art. To provide adjustability to the chain

31

, adjusting screw

45

coacts between a flange

47

attached to end frame member

20

and an idler sprocket

49

which serves to adjust the tension on chain

31

.

Actuation of the control

15

energizes the motor

41

to rotate the drive wheels

23

in synchronization and move the carriage

10

along the rails

12

a

,

12

b

and

12

c

. Appropriate controls are provided to start the carriage moving in either direction, and to stop the carriage at a desired location along the rails.

FIGS. 6-8

show three alternate embodiments of structures provided to guide the carriage

10

along the rails

12

a

,

12

b

and

12

c

. In the embodiment of

FIG. 6

each drive wheel

23

is formed with an annular flange

49

that extends concentrically from the wheel peripheral bearing surface

50

. The drive wheel flanges

49

interfit within grooves

51

formed in the top surface of the rail

12

a

. In

FIG. 6

, reference numeral

52

represents decorative or safety floor panels placed between the rails, as is known in the art.

Turning to

FIG. 7

, an alternative version of a wheel and rail configuration usable in conjunction with the present invention is illustrated. In

FIG. 7

there is seen an alternative form of supporting rail

54

which has a T-shaped upper supporting surface

55

. A wheel

56

having a flat outer perimeter

57

supports the carriage

19

for rolling movement along rail

55

. In order to prevent tipping of the carriage, it is preferred that clips

58

be attached as illustrated to cross frame members

20

and

21

. It will be noted that the clips

58

, which engage the upper T-shaped portion of rail

54

, thus effectively prevent tipping of the carriage.

A still further embodiment of a wheel and rail configuration is illustrated in FIG.

8

. In

FIG. 8

an alternative rail

60

is of a square or rectangular cross-section. Rail

60

rollingly supports wheels

61

which are provided with a central flat surface

62

and side flanges

63

along each side thereof which extend outwardly from each side of the flat supporting surface

62

which rides along rail

60

. Flanges

63

thus effectively keep the wheel

61

rolling along rail

60

as in the case of the flange

49

in the embodiment of FIG.

6

. In order to provide an anti-tip mechanism for the version shown in

FIG. 8

, a generally C-shaped channel

64

is provided under rail

60

. Inwardly extending ends

66

of channel

64

house downwardly extending clips

67

which, as shown, are affixed to cross frame members

21

. Thus, tipping of the carriage supported on frame

19

is effectively prevented.

Referring to

FIG. 3

, an alternate embodiment of an electrically powered mobile carriage is illustrated. In this embodiment five rails

80

a

-

80

e

support a carriage frame

81

. Non-powered supporting wheels

11

rollingly support the carriage

81

for movement along the associated rails

80

a

,

80

c

and

80

e

. Driven, synchronously powered pairs of wheels

23

are provided on at least two of the rails, in the illustrated embodiment, rails

80

b

and

80

d

. These wheels are driven by drive shaft

35

which is powered by motor/speed reducer

41

. The remaining components of the design of

FIG. 3

, including the drive wheels

23

and sprockets

29

, etc., are the same as for the design described previously.

A manually powered mobile carriage, the specific details of which are described in my above-noted issued '351 patent, may also be used as an alternate construction.

Thus, it is apparent that there has been provided, in accordance with the invention, mobile carriage that fully satisfies the aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the appended claims.