GB2102888A

GB2102888A - Rotary positive-displacement pumps

Info

Publication number: GB2102888A
Application number: GB08123828A
Authority: GB
Inventors: Naosuke Masuda; Takeshi Ohe; Tadaaki Fujii
Original assignee: Jidosha Kiki Co Ltd
Current assignee: Jidosha Kiki Co Ltd
Priority date: 1981-08-04
Filing date: 1981-08-04
Publication date: 1983-02-09
Also published as: GB2102888B

Abstract

A plurality of sliding-vane pump- sections 7, 8 are disposed in tandem on a common drive-shaft 14 within a body 1, 2. Each of the pump sections includes a cam ring 9 or 17 encircling rotor 12 or 19 having sliding vanes 13 or 20 thereon, and a pair of sideplates (10, 11 or 11, 18) abutting the cam ring. The outermost sideplates (10, 18) may be subject to the discharge pressure of the respective pump sections to hold the various components of the pump sections together and against a step 3 in the body and thereby minimise leakage. The flow-paths through the pump sections may be connected in parallel. <IMAGE>

Description

SPECIFICATION Pump unit The invention relates to a pump unit, and more particularly, to a pump unit including a plurality of pump sections of vane type which are driven by a common drive shaft.

A pump unit is known in the art in which a pair of pump sections of vane type are adapted to be driven by a common drive shaft. In the conventional arrangement, a pair of vane pumps are simply interconnected. In other words, the bodies of the individual vane pumps are connected together to permit a shared use of a drive shaft. Consequently, the body is interposed between the pump sections to increase the spacing therebetween, resulting in an increased overall size of the pump unit. In addition, the drive shaft which is used to drive the individual pump sections must have an increased rigidity. Another disadvantage relates to the time and labor which is required to assemble the single pump unit and which is substantially equal to the time and labor required to assemble a pair of vane pumps.

It is therefore an object of the invention to provide a pump unit which is reduced in size and weight and easy to assemble.

In accordance with the invention, there is provided a pump unit including a plurality of pump sections of vane type, each of which is driven by a common drive shaft to provide a pumping action. The pump unit is characterized in that an opening is formed in a body in which the individual pump sections are received in mutual contact with each other. This permits the axial length of the drive shaft to be reduced as compared with the prior art. Accordingly, the rigidity required of the drive shaft may be reduced, or alternatively the wobbling of the drive shaft may be reduced to decrease a pulsation in the discharge pressures from the respective pump sections. The plurality of pump sections which are maintained in mutual contact with each other permit them to be integrally assembled together in a sequential manner.

According to another aspect of the invention, the individual pump sections are received in the opening formed in the body of the pump unit in a manner to permit their axial displacement while maintaining them in mutual contact with each other. Each pump section is defined by respective sideplates, and at least one of the sideplates which is located outermost is subject to a discharge pressure from the associated pump section. In this manner, such discharge pressure can be utilized to maintain the components of the individual pump sections in a required urged position. Since the components are properly maintained in this manner, a liquid leakage between adjacent components is prevented, contributing to a further improvement of the pump performance while simultaneously simplifying the assembly.

An embodiment of the invention is described by way of example with reference to the attached drawings.

Fig. 1 is a cross section of one embodiment of the invention; and Fig. 1 is a cross section taken along the line Il-Il shown in Fig. 1.

Referring to Figs. 1 and 2, the pump unit shown includes a rear body 1 in which an opening 2 is formed with its one end being closed. A step 3 is formed substantially at the center of the opening 2, providing an opening 2a of an increased diameter toward the front side and an opening 2b of a reduced diameter toward the bottom side. The pump unit also includes a front body 4 which is secured to the rear body 1 by means of bolts 5, with a seal 6 interposed therebetween. A first pump section 7 and a second pump section 8 are received in the opening 2.

The first pump section 7 is constructed in the similar as a conventional vane pump, and comprises a cam ring 9 having a cam surface formed along its inner periphery, a pair of sideplates 10, 11 disposed to close the opposite end faces of the cam ring 9, a rotor 12 which is rotatable within the cam ring 9, a plurality of vanes 13 provided on the rotor 12, and a drive shaft 14 to which the rotor 12 is splined to be driven thereby for rotation. The sideplate 10 which is located within the larger opening 2a has an outer diameter which is equal to the inner diameter of such opening, and is slidably fitted therein.The other sideplate 11 which is disposed in the region of the step 3 has a stepped configuration so as to be simultaneously fitted into the two openings 2a, 2b with a step between such portions disposed in abutment against the step 3. A spring 1 5 is interposed between the front body 4 and the sideplate 10 for urging the entire first pump section 7 in a direction to maintain the step formed in the sideplate 11 to be disposed in abutment against the stpe 3 formed in the opening 2. In this manner, the axial position of the first pump section 7 is controlled while preventing a liquid leakage during the pump operation.The front body 4 is provided with a pair of positioning pins 1 6 which extend through the opening 2 in parallel relationship with the drive shaft 1 4. The positioning pins slidably extend through the cam ring 9 and the pair of sideplates 10, 1 which form the first pump section 7, adjacent their outer periphery, thereby angularly positioning the cam ring 9 relative to the pair of sideplates 10, 11.

The second pump section 8 is constructed in essentially the same manner as the first pump section 7, but shares the sideplate 1 1, which is located between the two pump sections, and the drive shaft 14 with the first pump section 7.

Specifically, the second pump section 8 comprises a cam ring 17, a pair of sideplates 11, 1 8 including the sideplate 11 mentioned above, a rotor 19, vanes 20 and the drive shaft 14 to which the rotor 1 9 is splined to be driven thereby for rotation. The cam ring 17, the rotor 19 and the vanes 20 of the second pump section 8 have axial dimensions which are greater than those of the first pump section 7, so that the second pump section 8 has a greater capacity than the first pump section 7. The sideplate 18 has an outer diameter which is equal to the inner diameter of the opening 2b and is slidably fitted therein.A spring 21 having a reduced resilience as compared with the spring 1 5 is interposed between the sideplate 1 8 and the bottom of the opening 2 to urge the components of the second pump section 8 in a direction toward the central sideplate 11 which is positioned by the step 3 and the spring 1 5 in the manner mentioned above.

The positioning pins 1 6 also slidably extend through the cam ring 1 7 and the sideplate 1 8 of the second pump section 8, in a region adjacent to the outer periphery, thus angularly positioning the cam ring 1 7 relative to the sideplate 18. It is desirable that the cam rings 9, 1 7 of the two pump sections 7, 8 be disposed out of phase as viewed in the direction of rotation of the drive shaft 14, so that pulsations occurring in the discharge pressure from one of the pump sections be out of phase from pulsations in the discharge pressure from the other pump section, with an overall effect that a smooth pumping action is achieved.

Low pressure chambers 22, 23, representing the suction side of the pump unit, are formed in the clearance between the outer periphery of the cam rings 9, 1 7 and the inner periphery of the opening 2, and communicate with each other through a communication hole 24 formed in the central sideplate 11. These low pressure chambers 22, 23 communicate, through a pair of passages 25, 26 formed in the rear body 1 and through a transverse passage 27 providing a communication between these passages 25, 26, with a fluid intake port 28 which opens into the body 1, and also communicate with the interior of the respective pump sections 7, 8 through intake openings 29, 30 which are formed in the pairs of sideplates 10, 11 and 11, 18 at given positions.

Discharge openings 31, 32 are formed in the pairs of sideplates 10, 11 and 11, 18 at given positions. The discharge opening 31 of the first pump section 7 communicates with a high pressure chamber 34 in which the spring 1 5 is disposed while the discharge opening 32 of the second pump section 8 communicates with a high pressure chamber 36 in which the spring 21 Is disposed. As indicated by phantom lines in Fig.

1, each of the high pressure chambers 34, 36 communicates with an associated discharge port, not shown, either directly or through a flow control valve 40, disposed within the rear body 1, through passages 37, 38 and 39 which are formed at locations where they do not communicate with the passages 25, 26, 27 and 28 of the intake side.

The flow control valve 40 is well known in the art, and hence its specific construction and operation will not be described. Any conventional arrangement may be used as the flow control valve 40. Alternatively, a flow control valve of the type disclosed in Japanese Laid-Open Patent Application No. 14,923/1980 may be used which permits the entire discharge from the discharge ports to be supplied to a fluidic instrument as long as the discharge from the respective pump sections 7, 8 is small, but which causes part of the discharge from the pump section 8 to be bypassed when its discharge reaches a given value, with the amount of bypass being eventually increased to the full discharge from the pump section 8.

During assembly, the drive shaft 14 and the positioning pins 1 6 are initially mounted in the front body 4, and then the spring 15, the first pump section 7, the second pump section 8 and the spring 21 are sequentially assembled on the drive shaft 14 and the positioning pins 16 so as to be received in the opening 2 of the rear body 1.

The front body 4 may then be connected together with the rear body 1 by means of the bolts 5, thus completing the assembly with labor and time which is substantially comparable to the assembly of a single vane pump. In particular, since the sideplate 11 is shared by the both pump sections 7, 8 in the present embodiment, the number of parts as well as the weight are reduced while permitting the spacing between the both pump sections 7, 8, in particular, between the cam rings 9, 1 7 to be reduced. Since the opening 2 has the bottom, it can be closed by a single lid member or front body 4. Again, the number of parts as well as the weight can be reduced as compared with an arrangement in which the opening 2 is formed as a through-opening to be closed at its both ends. This also contributes to simplifying the assembly and preventing a liquid leakage.In addition, the positioning pins 1 6 serve adjusting the phase relationship between the cam rings 9, 17 and the sideplates 10, 11 and 18. It is to be particularly pointed out that if the first pump section 7 and the second pump section 8 are disposed to be out of phase with respect to each other, they can be easily assembled to a given phase relationship and with a high accuracy.

In operation, as the drive shaft 14 rotates, the rotors 1 2, 1 9 of the respective pump sections 7, 8 are driven for rotation, thus withdrawing the fluid present in the individual low pressure chambers 22, 23 into the space defined by the respective vanes 1 3, 20 through the intake openings 29, 30, generally in the same manner as in a conventional vane pump. Thereafter, the fluid withdrawn is discharged into the respective high pressure chambers 34, 36 through the individual discharge openings 31, 32. The discharge pressure introduced into each high pressure chamber urges the components of the respective pump sections 7, 8 in the same manner as achieved by the resilience of the springs 1 5, 21 disposed in the respective high pressure chambers. However, it will be noted that the sideplates 10, 18 which are located outermost are subject to the discharge pressure. Obviously, the sideplate 10 which is fitted into the larger opening 2a has a greater surface area which is subject to the pressure, so that the central sideplate 11 is held in abutment against the step 3 in the same manner as such abutment is achieved by a differential resilience between the springs 1 5, 21. The components of the respective pump sections 7, 8 are sequentially disposed in abutment against each other with the sideplate 11 located at the center. Consequently, no careful attention is required during the assembly, the only requirement being that the components be manufactured to given accuracies.The various components are then urged to and maintained at given axial positions referenced to the sideplate 11 under the resilience of the springs 1 5, 21 and the discharge pressure, in a manner to prevent any liquid leakage therebetween. As an alternative arrangement, the sideplate 1 8 disposed within the smaller opening 2b may be chosen as a reference member fixed in relation to the body, against which other components of the pump sections 7, 8 may be disposed in abutment.

The hydraulic fluid discharged into the high pressure chambers 34, 36 is fed through the passages 37, 38 and 39 to the flow control valve 40 where the flow rate is controlled in accordance with the design of the valve, to be supplied to the fluidic instrument through discharge port, not shown. The fluid from the instrument is returned into the rear body 1 through the intake port 28, and then fed through the passages 27, 26 and 25 into the low pressure chambers 22, 23.

While the pump sections 7, 8 of vane type shown in the embodiment described above are of a balanced pressure type, it should be understood that the invention is equally applicable to any other type of vane pumps including a pressure imbalance type.

Claims

1. A pump unit including a plurality of pump sections of vane type, which are driven by a common drive shaft to provide a pumping action wherein the plurality of pump sections are received in an opening in the body of the pump unit, directly adjacent one-to-another.

2. A pump unit according to claim 1 in which each of the pump sections is defined by a pair of sideplates, the sideplate which is located between the or each adjacent pair of pump sections being common to the two pump sections.

3. A pump unit according to claim 1 or claim 2 in which the body comprises a first body part in which the said opening is formed as a recess having a bottom and a second body part in the form of a lid member which closes the recess, the said body parts being integrally connected together after the respective pump sections are received within the opening.

4. A pump unit according to any one of claims 1 to 3 in which the body carries a positioning pin which extends through the opening in parallel relationship with the drive shaft, the positioning pin extending through a cam ring and sideplates which form each of the pump sections, thereby controlling the angular position of the cam ring with respect to the sideplates.

5. A pump unit including a plurality of pump sections of vane type, which are driven by a common drive shaft to provide a pumping action, wherein the respective pump sections are received in an opening formed in the body of the pump unit directly adjacent one-to-another and in a manner to permit their axial displacement, and each of the pump sections is defined by a pair of sideplates, at ieast one of the sideplates which are located outermost being subject to a discharge pressure from the associated pump section.

6. A pump unit according to claim 5 in which said one sideplate is resiliently urged by a spring in the direction in which the sideplate is urged by the discharge pressure.

7. A pump unit according to claim 5 or claim 6 in which the other of the outermost sideplates is fixed in position relative to the body, while the remaining sideplate(s) and cam rings which define the respective pump sections are sequentially disposed in abutment against each other and so held in position with reference to the fixed sideplate under the influence of the discharge pressure.

8. A pump unit according to claim 5 or claim 6 in which one of the cam rings of the respective pump section or the or one of the remaining sideplates located intermediate the outermost sideplates is fixed in position relative to the body, and wherein the two outermost sideplates are subject to respective discharge pressures from pump sections, whereby the remaining sideplate(s) and the cam rings (other than the fixed sideplate or cam ring) are subject to the discharge pressures so as to be sequentially disposed in abutment against each other in either sides of the fixed sideplate or cam ring.

9. A pump unit according to claim 8 in which the opening formed in the body is stepped to provide a larger diameter portion and a smaller diameter portion, one of cam rings of the respective pump sections or one of the remaining sideplate(s) located intermediate the outermost sideplates being fixed in relation to the body by being disposed in abutment against the step formed between the larger and the smaller diameter portions of the opening under a bias applied in one direction, that one of the outermost sideplates which is subject to the discharge pressure so as to urge said fixed sideplate or cam ring against the step having a greater surface area subject to the discharge pressure than the other of the outermost sideplate which operates to urge the fixed sideplate or cam ring away from the step under the action of the discharge pressure.

10. A pump unit substantially as herein described with reference to and as shown in the accompanying drawings.