Self aligning cartridge pump

TECHNICAL FIELD

The present invention relates generally to a cartridge pump, and more particularly to a cartridge pump with self-aligning features.

BACKGROUND

A wide variety of cartridge pumps are known in the prior art. Cartridge pumps are used in a wide variety of applications. Commonly cartridge pumps consist of a cartridge housing surrounding a pumping mechanism (or cam-pack). Passageways formed within the cartridge housing allow fluid to communicate with the pumping mechanism. Often, an external motor and drive shaft are used to power the pumping mechanism within the cartridge pump.

It is known, however, that the interaction between the external motor and drive shaft and the pumping mechanism within the cartridge pump can interfere with the proper operation of the cartridge pump. If the axis of the drive shaft is not perpendicular to the pumping mechanism, it is possible that the pumping mechanism may be angled within the cartridge housing. At a minimum, such a situation can result in increased friction and increased force required to active the cartridge pump. In more extreme examples, this situation may result in incorrect operation of the cartridge pump, damage to the cartridge pump, or even failure of the cartridge pump. This is highly undesirable.

Proper alignment of the cartridge pump with the external drive shaft is commonly accomplished through the use of tight tolerances in manufacturing and assembly. Although such procedures can reduce incidents of misalignment, they can also increase the cost and time of assembly and manufacturing. In addition, misalignment can still occur in post manufacturing situations such as repair, replacement, or even vibrations during use.

It would, therefore, be highly desirable to have a cartridge pump with improved alignment characteristics and without the need for tight manufacturing and assembly tolerances. In addition, it would be highly desirable to have a cartridge pump whose alignment characteristics would help provide proper alignment with the drive shaft in post manufacturing and assembly situations.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a cartridge pump with improved alignment characteristics. It is a further object of the present invention to provide such improved alignment characteristics without the need for increased manufacturing and assembly tolerances.

In accordance with the objects of the present invention, a self-aligning cartridge pump for use with an external drive shaft is provided. The self-aligning cartridge pump includes a pumping mechanism, a cylindrical cartridge housing, and a retaining ring. The cylindrical cartridge housing has a curved upper plate. The retaining ring is in communication with the curved upper plate and allows the cartridge housing to pivot. The ability of the cylindrical cartridge housing to pivot on its connection with the retaining ring permits the pumping mechanism to naturally align perpendicularly with the drive shaft.

Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is an illustration of an embodiment of a self-aligning cartridge pump in accordance with the present invention; and

FIG. 2

is a cross-sectional illustration of an embodiment of a self-aligning cartridge steering pump in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to

FIG. 1

, which is an illustration of a self-aligning cartridge pump

10

in accordance with the present invention. Self-aligning cartridge pump

10

is preferably for use in an automotive power steering system, although a self-aligning cartridge pump

10

may be used in a wide variety of applications, including non-automotive applications.

Referring now to

FIG. 2

, which is a cross-sectional illustration of a self-aligning cartridge pump

10

in accordance with the present invention shown positioned within a motor housing

14

. The motor housing

14

is shown strictly for illustrative purposes, and is not intended to create a limitation of the present invention. A wide variety of motor housings

14

and other encasements may be used to hold the self-aligning cartridge pump

10

. The motor housing

14

is illustrated showing an input reservoir

16

, an output reservoir

18

, a drive shaft

20

, and shaft bearings

22

. Although these elements are shown, it should be understood that a vast array of motor housing

14

designs are well known in the prior art and contemplated by the invention.

The input shaft

20

is used to engage and drive a pumping mechanism

24

positioned within a cylindrical cartridge housing

25

of the self-aligning cartridge pump

10

. Although a wide variety of pumping mechanisms

24

are well known in the prior art one contemplated pumping mechanism

24

includes cam element

26

and vane elements

28

. Other pumping mechanisms

24

such as impellers and other known systems are also contemplated by the invention. In the prior art, a misalignment between the input shaft

20

and the pumping mechanism

25

has been known to lead to potential problems in pump operation. A misalignment may cause undesirable friction between pumping mechanism

24

and the cylindrical cartridge housing

25

. This may lead to improper operation of the pumping mechanism

24

, or even damage to the pumping mechanism

24

.

The present invention includes a curved upper plate

30

and a retaining ring

32

. The curved upper plate

30

allows the self-aligning cartridge pump

10

to pivot against retaining ring

32

and thereby naturally align the pumping mechanism

24

with the input shaft

20

. The forces caused by misalignment with the input shaft

20

will cause the self-aligning cartridge pump

10

to shift into correct alignment. In addition, the curved upper plate

30

allows self-aligning cartridge pump

10

to be adequately secured in a variety of positions within the motor housing

14

by allowing retaining ring

32

to remain in constant contact with the self-aligning cartridge pump

10

throughout a variety of angles.

Although the retaining ring

32

is illustrated as a separate element, in other embodiments, it is possible for the retaining ring

32

to be formed directly as part of the motor housing

14

. In addition, although the curved upper plate

30

is shown with a particular curve, a wide variety of curved surfaces are contemplated. It is contemplated that the curve of the curved upper plate

30

may be adjusted to control the amount of pivot the self-aligning cartridge pump

10

is capable of moving. The self-aligning cartridge pump

10

may additionally include O-rings

34

. The O-rings

34

provide a seal between the self-aligning cartridge pump

10

and the motor housing

14

while additionally allowing the self-aligning cartridge pump

10

to pivot into correct alignment. Although the O-rings

34

are shown, a wide variety of mechanisms are known that would allow the self-aligning cartridge pump

10

to remain adequately sealed to the motor housing

14

while retaining its ability to pivot and correct alignment.

While the invention has been described in connection with one or more embodiments, it is to be understood that the specific mechanisms and techniques which have been described are merely illustrative of the principles of the invention, numerous modifications may be made to the methods and apparatus described without departing from the spirit and scope of the invention as defined by the appended claims.