GB2034820A

GB2034820A - Rotary positive-displacement fluid-machines

Info

Publication number: GB2034820A
Application number: GB7845849A
Authority: GB
Original assignee: Kayaba Industry Co Ltd
Current assignee: KYB Corp
Priority date: 1978-11-23
Filing date: 1978-11-23
Publication date: 1980-06-11
Also published as: GB2034820B

Abstract

In a gear pump or motor of the kind comprising two (or more) units 11, 12 having respective shafts 20..23 an intermediate casing 29 is interposed between the two units and supports the inner shafts 21, 23. A common inlet port is provided in the casing and when the machine is being assembled a sleeve 37 is inserted through this port into a chamber 31 so as to interconnect the opposing ends 36 of the torque-transmitting inner shafts 23. <IMAGE>

Description

SPECIFICATION Improvements in or relating to gear pumps or gear motors The present invention relates to means for facilitating the spline interconnection between the opposing ends of the axially inwardly extended driving shafts of driving gears of coaxially disposed pump or motor units and more particularly improvements in or relating to gear pumps or motors, whereby in assembly the correct axial alignment and spline connection between the opposing driving shafts thereof may be facilitated.

The gear pump comprising two pump units which are substantially identical in structural and functional features is disclosed in as for example British Patent No. 982,014. Each pump unit comprises a casing member and a cover member, and a pair of intermeshing gears are disposed in the pumping chamber defined in the casing member. The axially outwardly extended shafts of the driven and driving gears are journalled in the cover member while the axially inwardly extended shafts thereof are journalled in the casing member itself. The radial mating surfaces of the two casing members are formed with recesses, which define a space when assembled, and with axial holes or bores for receiving locating or dowel pins. The two pump units are assembled together with the axially inwardly extended driving shafts into the space splined to each other with an internally splined sleeve.

The gear or motor of the type described above has some defects. First, when the opposing driving shafts are splined together, they must be correctly aligned in coaxial relationship. Consequently, the shaft holes or bores of the casing members must be correctly aligned. To this end, the locating holes and locating or dowel pins must be machined with a higher degree of accuracy so that highly skilled and experienced operators, high-precision machines and many machining steps are inevitably required, thus resulting in the increase in manufacturing cost. Second, in order to spline the driving shafts to each other with the internally splined sleeve, two separate or split casing members must be used and aligned correctly with respect with each other with the use of locating or dowel pins.As a result, the number of parts is increased, resulting in the increase both in material and fabrication costs.

Accordingly, one of the objects of the present invention is to provide an improved gear pump or motor wherein the correct axial alignment and spline interconnection between the axially inwardly extended or opposing driving shafts of the driving gears of two coaxial pump or motor units may be much facilitated.

Another object of the present invention is therefore to provide an improved gear pump or motor wherein the axially inwardly extended or opposing driving shafts of the two pump or motor units are journalled in a common shaft hole or bore extended through an intermediate casing which, in one embodiment of the present invention, is interposed between first and second gear pump casing each accommodating a pair of intermeshing driven and driving gears and their axially outwardly extended shafts.

To the above and other ends, briefly stated, the present invention provides a gear pump or motor which comprises at least two pump or motor units and wherein the axially outwardly extended or opposing driving shafts of the driving gears of the two pump or motor units are journalled in a common intermediate casing and spline connected to each other with an internally splined sleeve. The common casing has an inlet port which is communicated through low pressure passages with the pump chambers in the two pump or motor units (and with an assembly chamber or space into which are extended the externally splined inner ends of the opposing driving shafts). The diameter of the inlet port is made greater than the outer dimensions of the sleeve so that the latter may be inserted through the inlet opening into the assembly chamber or space and connected to the inner ends of the driving shafts.Thus the interconnection between the inner ends of the opposing driving shafts with the internally splined sleeve may be much facilitated. Furthermore, since the axially inwardly extended or opposing driving shafts are journalled in a common shaft hole or bore extended through the common intermediate casing, the correct axial alignment between them may be easily attained and maintained.

The above and other objects, features and advantages of the present invention will become more apparent from the following description of some preferred embodiments thereof taken in conjunction with the accompanying drawings.

Fig. 1 is a cross-sectional view taken in a first plane through a pump incorporating the principles of the present invention; Fig. 2 is a cross-sectional view taken in a second plane at right angles to the first plane of the first embodiment shown in Fig. 1; and Figs. 3 and 4 are cross-sectional views, respectively, of second and third embodiments of the present invention.

Same reference numerals are used to designate similar parts throughout Figs. 1 and 2; in Fig. 3 the same reference numeral as used in Figs: 1 and 2 plus 100 is used to designate a part similar to that shown in Figs. 1 and 2; and in like manner, the same reference numeral used in Figs. 1 and 2 plus 200 is used to designate a part similar to that shown in Figs. 1 and 2.

The present invention will be described as being applied to a gear motor, but it is to be understood that it may be equally applied to gear motors.

FirstEmbodiment, Figs. I and 2 Referring to Figs. 1 and 2, a gear pump 10, to which is applied the present invention, is of the two unit construction having a first pump unit 11 and a second pump unit 12, both of which are substantially similar in construction and operation to each other.

The first and second pump units 11 and 12 have radial mating surfaces 13, each of which is formed with a recess in the form of a figure eight which defines a pump chamber 14. Blind holes or bores 1 5 for receiving the axially outwardly extended shafts 20, and 22 of two pairs of intermeshing impeller gears or driven and driving gears 1 8 and 1 9 are formed axially and in parallel with each other in the bottoms or the closed radial ends of the pump chambers 14. Bushings 25 are pressed into these blind holes or bores 1 5. The hole or bore 15 for journalling the driving shaft 22 of the driving gear 19 of the first pump unit 11 is extended axially through the first casing 1 6.

Each pair of intermeshing driven and driving gears 1 8 and 1 9 are disposed for rotation in the pump chamber 14 with their shafts 20, and 22 journalled in the bushings 25. The shafts 20 and 21 are referred to as the driven shafts while the shafts 22 and 23, as the driving shafts.In order to liquid-tightly seal the side faces of the intermeshing gears 18 and 19, pressure plates 24 are pressed against them in such a way that the pressure plates 24 may be slidable along the shafts 20-23. Since the construction of these pressure plates 24 is of the conventional type and does not constitute the present invention, it will suffice only to explain that, as with the conventional ones, the rear surface of each of them has a high pressure zone and a low pressure zone which are separated from each other by seals 26 and which are communicated with the high and low pressure sides of the pump during operation, whereby the pressures exerting to the pressure plates 24 may be balanced and the pressure plates 24 may effectively liquid-tightly steal the side faces of the intermeshing gears 1 8 and 19.

The drive shaft 22 of the driving gear 19 of the first pump unit 11 is extended axially through the hole or bore 1 5 beyond the first casing 1 6 and is drivingly coupled to an exterior prime mover (not shown). In order to seal this driving shaft 22, an oil seal assembly 27 is placed in and securely held in position with a snap ring 28 in a counterbore 15a of the hole or bore 15.

An intermediate casing 29, which is interposed between the first and second casings 1 6 and 1 7, is formed with two axial through holes or bores 30 for receiving therein the shafts 21 of the driven gears 18 and the driving shafts 23 of the driving gears 19. The two axial through holes or bores 30, which are in parallel with each other, are communicated with each other through an assembly chamber 31. Bushings 32 forjournalling the shafts 21 and 23 are pressed into these holes or bores 30 and their inner ends are axially spaced apart from each other by the assembly chamber 31. The first and second casings 1 6 and 1 7 and the intermediate casing 29 are assembled together with through bolts 34 and nuts.In this case, the body seals 33 are interposed between the radial mating surfaces of the first and second casings 1 6 and 17 on the one hand and those of the intermediate casing 29 on the other hand, and locating pins 35 are inserted into aligned blind holes formed in the mating surfaces of the first, second and intermediate casings 1 6, 1 7 and 29 as shown.

With the above construction, the driven shafts 21 of the driven gears 18 and the driving shafts 23 of the driving gears 19 are journalled by the bushings 32 press fitted into the axial through holes 30 of the intermediate casing 29. Since these axial through holes or bores 30 may be simultaneously machined with a higher degree of accuracy, the driven shafts 21 of the driven gears 1 8 and the driving shafts 23 of the driving gears 18 may be accurately aligned with each other in the axial through holes or bores 30.Furthermore, the locating or dowel pins 35 serve to attain and maintain the correct alignment between the first, second and intermediate casings 1 6, 1 7 and 29, whereby the correct alignments between the axial through holes 30 in the intermediate casing 29 and the holes or bores 1 5 in the first and second casings 1 6 and 17.

In order to transmit the driving power from the prime mover (not shown) through the first pump unit 11 to the second pump unit 12, the inner opposing ends of the driving shafts 23 of the first and second driving gears 1 9 are extended into the chamber 31 externally splined and connected to each other through an internally splined sleeve 37.

Thus, the single prime mover (not shown) may simulataneously drive both the first and second pump units 11 and 12.

In assembly, the sleeve 27 is inserted through an inlet port 38 formed in the intermediate casing 29 and opened at one side wall thereof as best shown in Fig. 2. The inlet port 38 is communicated not only with the chamber 31 in the intermediate casing 29 but also low-pressure passages 39 which are extended in parallel with the axes of the intermeshing driven and driving gears 1 8 and 19 through the first, second and intermediate casings 16, 1 7 and 29.

Two outlet ports 40 are formed through the side walls of the first and second casings 1 6 and 17 on the opposite side of the inlet port 38 as best shown in Fig. 2. These outlet ports 40 are in communication with high pressure passages 41 extended through the first and second casings 1 6 and 17 in parallel with the axes of the intermeshing gears 18 and 19.

The low pressure passage 39 are communciated with the pump chambers 1 4 in opposed relationship with the portions at which the driven and driving gears 1 8 and 1 9 disengage from each other. In like manner, the high pressure passages 41 are communicated with the pump chambers 14 in opposed relationship with the portions at which the driven and driving gears 18 and 1 9 intermesh each other as is well known in the gear pump and motor techniques.

The inner diameter of the inlet port 38 is larger than the outer diameter of the internally splined sleeve which interconnects the driving shafts 23 of the driving gears 1 9 of the first and second pump units 11 and 1 2 so that, as described hereinbefore, in an assembly line an operator may insert the sleeve 37 through the inlet port 38 into the communication chamber or passage 31 and have it engaged with the shafts 23 so as to interconnect them.

Next the mode of operation of the gear pump 10 with the above construction will be described.

As the intermeshing gears 1 8 and 1 9 are driven, the liquid is sucked through the inlet port 38, flows through the low pressure passages 39, is impounded in the spaces between the teeth of the intermeshing driven and driving gears 18 and 19, carried around the casings 1 6 and 1 7 into the high pressure passages 41 and then discharged through the outlet ports 40.

Second Embodiment, Figs. 3 The second embodiment shown in Fig. 3 is substantially similar in construction and mode of operation to the first embodiment described above with reference to Figs. 1 and 2 except that the first and second casings 1 6 and 1 7 are formed integral with the intermediate casing 29 as a unitary construction and the outer shafts of the intermeshing gears are journalled in the cover members securely and liquid-tightly attached to the casing.

More particularly, a. gear pump 110 of the second embodiment has two pump units 111 and 112 and has a pump housing consisting of a pump casing 129 and cover members 16 and 1 7 securely and liquid-tightly attached to the ends of the casing 1 29. Pump chambers 114 are recessed in the end surfaces of the casing 129 for accommodating therein the intermeshing driven and driving gears 118 and 119. The cover members 116 and 1 1-7 are formed with the holes or bores for receiving therein the outwardly extended shafts 120 and 122 of the driven and driving gears 11 8 and 11 9. The above description will suffice to distinguish the second embodiment from the first embodiment so that no further description shall be made.

The second embodiment is also advantageous in that the connection and correct alignment between the driving shafts 123 of the driving gears 119 of the first and second pump units 111 and 112 may be much facilitated.

Third Embodiment, Figs. 4 The third embodiment shown in Fig. 4 has three pump units 211,212 and 213, but it is to be understood that the number of pump units may be increased as many as desired as will become apparent from the following description. the third embodiment is substantially similar in construction to the first embodiment of Figs. 1 and 2 except that the first or second casing 1 6 and 1 7 is splitted into a cover member 216 or 217 and a pump chamber casing 229a and a pump chamber casing 229a is interposed between the intermediate casings 229. As with the second embodiment shown in Fig. 3, the cover members 216 and 217 are adapted to the outwardly extended shafts of the driven and driving gears of the outermost pump units 211 and 212.The pump chamber casing 229a which has a pump chamber 214 for accommodating a pair of intermeshing driven and driving gears 218 and 219 is adapted to be interposed between the cover member 21 6 or 21 7 and the intermediate casing 229 or between the intermediate casings 229. Thus it is readily seen that the number of pump units may be increased as many as desired.

However, in the third embodiment, when the width of the driven and driving gears 218 and 219 is short and consequently the width of the pump chamber casing 229a is short, it sometimes becomes difficult to open the discharge or outlet ports at the side wall of the pump chamber casing 229a. In this case as with the low-pressure passages the high pressure passages (now shown) are extended in parallel with the axes of the intermeshing gears 21 8 and 21 9 through the cover members 21 6 and 21 7 and the intermediate casings 229 and communicated with the discharge or outlet ports which are opened through the side walls of the cover members 216 and 21 7 and the intermediate members 229.

Claims

1. In a gear pump or a gear motor, a combination comprising at least two pump or motor unit casings each having a pump chamber for accommodating a pair of intermeshing driven and driving gears and shaft receiving holes or bores axially extended forjournalling the outwardly extended shafts of said intermeshing gears, an intermediate casing adapted to be interposed between said two pump or motor unit casings and formed with two axially extended through holes or bores adapted to journal the inwardly extended shafts of said intermeshing gears, one of said two axially extended through holes or bores being adapted to journal both the inwardly extended shafts of the driven or driving gears while the other being adapted to journal both the inwardly extended shafts of the driving or driven gears, a common inlet port communicated through lowpressure passages with a pump chambers in said pump or motor unit casing, and a sleeve which may be inserted through said common inlet port into said intermediate casing so as to interconnect the opposing ends of said inwardly extended shafts of said driving gears.

2. A combination as set forth in Claim 1 wherein said intermediate casing is formed with an assembly chamber or opening communicated with both said two axial through holes or bores at the intermediate between their ends and with said common inlet port, whereby said sleeve may be inserted through said common inlet port into said assembly chamber or opening and be connected to both the opposite ends of the inwardly extended shafts of said drivinq qears.

3. A combination as set forth in Claim 1 wherein said pump chamber of each of said pump or motor unit casings is defined as a recess formed in the radial mating surface thereof adapted to be joined to the radial mating surface of said intermediate casing.

4. A combination as set forth in Claim 1 wherein said pump chambers are not formed in said pump or motor unit casings but are defined as recesses formed in the radial mating surfaces of said intermediate casing adapted to mate with the corresponding radial mating surfaces of said pump or motor unit casings.

5. A combination as set forth in Claim 1 wherein each of said pump or motor unit casings is splitted into a pump chamber casing having a pump chamber defined therein and a cover member adapted to journal said outwardly extended shafts of said driven and driving gears and securely and liquid-tightly attached to said pump chamber casing and a combination of said pump chamber casing and said intermediate casing is interposed as many as desired between the outermost pump chamber casings.

6. A gear pump or motor constructed, arranged and operating substantially as described with reference to Figs. 1 and 2.

7. A gear pump or motor constructed, arranged and operating substantially as described with reference to Fig. 4.

8. A gear pump or motor constructed, arranged and operating substantially as described with reference to Fig. 4.

9. A gear pump or gear motor substantially as hereinbefore described with reference to, and as illustrated in, the accompanying diagrammatic drawings.

10. Any features of novelty, taken singly or in combination, of the invention as hereinbefore described with reference to the accompanying diagrammatic drawings.