JP2003049763A - Double variable displacement axial piston pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double variable displacement axial piston pump that can unify external control command systems and can realize a large displacement, a low pulsation and low noise. SOLUTION: An upper portion of a first swash plate 3 incorporated in a first pump is abutted by an operating piston for actuating the first swash plate via an external control command, and a lower portion of the first swash plate is abutted by one end face of a connecting rod 6 held axially slidable. The connecting rod extends to a second pump through an intermediate 7, and the other end face of the connecting rod abuts on a lower portion of a second swash plate 17 incorporated in the second pump. An upper portion of the second swash plate is abutted by at least either of an initially loaded return spring 13 or a bias piston 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual variable displacement axial piston pump in which a first pump and a second pump are coaxially driven.

[0002]

2. Description of the Related Art Generally, in order to increase the capacity of a variable displacement axial piston pump, the size of the pump itself is increased, or a pump having a small capacity is coaxially connected and operated by one drive source. The technology is known.

[0003]

However, when the size of the pump itself is increased, the cost of the material itself is high because the size of each component is increased, and a lot of labor is required for processing and assembling work. I was there.

On the other hand, in the case of coupling two pumps having a small capacity, if each pump is simply coupled coaxially, for example, when it is desired to control the discharge capacity of each pump, the The control becomes complicated because it is necessary to separately provide the control command system.

Further, when the above-mentioned two pumps are combined, the pulsations of the fluid discharged from the two pumps are in phase with each other, so that the pulsations of the same phase are combined, and resonance and noise due to them are serious problems. It was

In view of the above-mentioned circumstances, the present invention is a dual variable capacity which can have a single control command system from the outside and can realize large capacity, low pulsation and low noise. An object is to provide a type axial piston pump.

[0007]

According to the first aspect of the present invention, the first pump and the second pump are coaxially arranged at positions facing each other via the intermediate body, and are operated by one drive source. In the swash plate type double variable displacement axial piston pump, an operation piston for operating the first swash plate according to a control command from the outside is brought into contact with an upper portion of the first swash plate incorporated in the first pump, One end surface of a connecting rod held slidably in the axial direction is brought into contact with a lower portion of the first swash plate, and the connecting rod extends through the intermediate body to the second pump side. The other end surface of the connecting rod is in contact with a lower portion of a second swash plate incorporated in the second pump, and an upper portion of the second swash plate has at least one of a return spring having an initial load or a bias piston. It has a structure that is in contact.

That is, according to the present invention, as shown in FIG.
The operation piston 5 is in contact with the swash plate 3, the first swash plate 3 is connected to the second swash plate 17 by the connecting rod 6, and the return spring 13 and the bias piston 14 are attached to the second swash plate 17. Since they are in contact with each other, the operating piston 5 is controlled by an external control command (for example, a flow rate control command).
Is operated in the axial direction, the first swash plate 3 and the second swash plate 17 can be simultaneously operated via the connecting rod 6. Therefore, it is possible to simultaneously control the first pump and the second pump with a common control command from the outside.

According to the invention described in claim 2, claim 1
In the dual variable displacement axial piston pump according to claim 1, the respective suction ports of the first pump and the second pump communicate with each other inside the intermediate body, and the respective discharge ports of the first pump and the second pump have the intermediate The intermediate body has a common suction port and a common discharge port that are connected to the outside as a connection port that communicates with the inside of the body and communicates with both the suction ports that communicate with each other and the discharge ports that communicate with each other. It has been configured.

This simplifies the external connection to the intermediate body (that is, since there is only one suction flange 18 and one discharge flange 19 as shown in FIG. 2), it is as if one small capacity pump were used. It can be handled as if it is being used.

According to the invention of claim 3, claim 1
Alternatively, in the double variable displacement axial piston pump according to the aspect 2, the first cylinder block incorporated in the first pump and the second cylinder block incorporated in the second pump have rotational phases of pistons of each other. Are attached to the rotary drive shaft so that they do not match.

Due to the structure of the piston pump, the fluid becomes an intermittent flow, which causes a problem of pulsation. In the conventional technique, the rotation phase of the piston of the cylinder block built in the first pump that rotates on the same axis and the rotation phase of the piston of the cylinder block built in the second pump match each other. The pulsation of the discharge fluid of the pump completely matches, and the combined value of the pulsations generated from the two pumps is almost 2
Will be doubled.

However, according to the present invention, as shown in FIGS. 6 and 7, the arrangement of the piston holes 20 of the first cylinder block 4 incorporated in the first pump and the arrangement of the piston holes 20 in the second pump are incorporated. Piston hole 2 of second cylinder block 12
The phase in the rotation direction is different from the 0 array. That is,
A first cylinder block built into the first pump;
The second cylinder block incorporated in the second pump is rotated by the rotary drive shaft in a state where the rotational phases of the pistons do not match each other, so that the pulsation of the fluid sucked in by the first piston and the pulsation of the fluid discharged by the first piston The pulsations of the fluid that the two pistons suck in and expel are not exactly the same.
Therefore, the combined value of the pulsation can be suppressed as compared with the related art.

When the cylinder block having the same structure is used for the first pump and the second pump, in order to effectively reduce the pulsation, the arrangement of the piston holes of the first cylinder block and the piston holes of the second cylinder block is performed. The phase difference is preferably half of the arrangement pitch of the piston holes. 6 and 7
In the above example, the piston holes are drilled 9 by 9, so the arrangement pitch of the piston holes is 40 °.
That is, it is preferable to attach the first and second cylinder blocks to the rotary drive shaft with a phase difference of 20 °.

Further, by suppressing the pulsation, the noise caused by the pulsation can be reduced.

According to the invention of claim 4, claim 1
In the double variable displacement axial piston pump according to any one of items 1 to 3, the connecting rod is divided in the middle in the axial direction.

A first swash plate built in the first pump;
When the second swash plate incorporated in the second pump is operated at different tilt angles, that is, when the discharge capacity is different between the first pump and the second pump, the connecting rod is composed of only one member. If so, the eccentric distance between the position in contact with the first swash plate and the position in contact with the second swash plate does not match, so that the force of the connecting rod is transmitted axially between the first swash plate and the second swash plate. A force other than the component acts, which may impair the smoothness of axial movement of the connecting rod. Therefore, as shown in FIG. 8, in the present invention, the connecting rod is divided into two in the middle of the axial direction (6a and 6b in FIG. 8), and each of the divided connecting rods and each swash plate abut. At the same time, the difference between the eccentric distances of both connecting rods is absorbed by the contact portion between both rods. Of course, this is within the diameter of the connecting rod, preferably 1/3 of the diameter.
Although the degree of absorption is maximized, smooth transmission of force can be achieved by appropriately selecting the thickness of the connecting rod. The connecting rods divided into two parts may have the same diameter or different diameters.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In each of the drawings, the parts denoted by the same reference numerals as those in the drawings represent the same or corresponding parts.

FIG. 1 shows an example of an apparatus for carrying out the present invention, in which a first pump and a second pump are mounted so as to operate coaxially via an intermediate body 7. In the first pump, the operation piston 5, the first swash plate 3, the first piston 2, and the first cylinder block 4 are mainly contained in the first housing 1. On the other hand, in the second pump, the second swash plate 17, the second piston 15, the second cylinder block 12, the return spring 13, and the bias piston 14 are mainly housed in the second housing 16. The first shaft 8 of the first pump and the second shaft 11 of the second pump are coaxially connected to each other by the coupling 10, and are substantially one common rotary shaft drive as one drive source (not shown). ) Is driven by. When a drive source (typically an electric motor is used) is driven, the first shaft 8 and the second shaft 11 start rotating integrally, and with this rotation, the first piston 2 and the first cylinder block 4 are rotated. , And the second piston 15 and the second cylinder block 12 start rotating, and the liquid is sucked and discharged by the reciprocating motion of the piston according to the tilt angle of each swash plate 3, 17, and thus the first pump And the second pump operates at the same time.

The operating piston 5 is in contact with the upper portion of the first swash plate 3 and controls the inclination of the first swash plate 3 according to the operation of the control valve 9. That is, an external command (for example, a flow control command)
When the control valve 9 is actuated, the control valve 9 is operated, and the first swash plate 3 is controlled so that the operating piston 5 tilts according to the command. The lower portion of the first swash plate 3 is connected to the second swash plate 17 via the connecting rod 6, and the return spring 13 and the bias piston 14 are in contact with the upper portion of the second swash plate 17. Therefore, once the operating piston 5
Thus, when the inclination of the first swash plate 3 is controlled, the inclination of the second swash plate 17 can be simultaneously controlled via the connecting rod 6. This allows a single control command system from the outside, and eliminates the need for an extra control system.

Further, it is sufficient to provide only one control valve 9 and it is not necessary to provide an extra control valve, so that the structure can be simplified and the cost can be reduced.

Although FIG. 1 shows an embodiment in which both the return spring 13 and the bias piston 14 are provided, a structure in which only one of them is provided may be adopted.

2 to 5 show details of the intermediate 7. 2 is a front view of the intermediate body 7, FIG. 3 is a left side view, FIG. 4 is a right side view, and FIG.

As shown in FIG. 2, the intermediate body 7 has such a structure that the fluid is sucked into the pump from the right side and the fluid compressed by the pump is discharged to the left side. The suction flange 18 shown in FIG. The discharge flanges 19 shown in FIG. As shown in FIG. 5, the intermediate body 7 includes therein a suction passage 21 common to two pumps, and
One common discharge passage 22 is provided, and the suction passage 21 is communicated with the suction flange 18 and the discharge passage 22 is communicated with the discharge flange 19, respectively.
By connecting the piping to, it is possible to handle as if using a single pump.

FIG. 6 shows a sectional view of the first cylinder block 4, and FIG. 7 shows a sectional view of the second cylinder block 12. 6 and 7, nine piston holes 20 are opened so that nine pistons can be mounted. In the first cylinder block shown in FIG. 6, the center of the piston hole 20 is located on the vertical axis, and nine piston holes are arranged at a 40 ° pitch in the circumferential direction with the center as the reference. On the other hand, in FIG.
The cylinder blocks have the centers of the piston holes 20 at positions inclined by 20 ° in the circumferential direction from the vertical axis, and are arranged at a pitch of 40 ° in the circumferential direction with reference to the center. That is, FIG.
The inner piston hole and the piston hole in FIG. 7 are attached to a common rotary drive shaft in a state of being displaced by half the pitch of the piston holes (20 ° in this embodiment). Since the two cylinder blocks simultaneously rotate with one drive shaft in a state where the piston holes are displaced, the phase of the cycle in which the fluid is sucked in and discharged from the piston is 20 between the first pump and the second pump. ° Pitch shifts. As a result, it is possible to prevent the pulsations of the fluid from completely matching each other and reduce the pulsations.

It is advisable to engrave the cylinder blocks 4 and 12 at a position of 20 ° shown in FIGS. 6 and 7 as a mark at the time of attachment to the rotary shaft.

The embodiment shown in FIGS. 6 and 7 shows the case where the number of pistons is 9, but this is not intended to limit the technical scope of the present invention.

The dual variable displacement axial piston pump of the present invention is not limited to the above-mentioned illustrated example, and various modifications can be made without departing from the scope of the present invention. is there.

[0029]

As described above, according to the dual variable displacement axial piston pump of the present invention, since both pumps can be controlled by one external command system, a control device is provided for each pump individually. No need. Therefore, not only control becomes easy, but also low cost can be realized. Further, the pump of the present invention can not only be easily increased in capacity, but also can exert significant effects on mechanical performance such as low pulsation and low noise.

[Brief description of drawings]

FIG. 1 is an overall assembly cross-sectional view showing an embodiment of the present invention.

FIG. 2 is a front view of an intermediate body that is a component in FIG.

FIG. 3 is a left side view of FIG.

FIG. 4 is a right side view of FIG.

5 is a view taken in the direction of the arrow Y in FIG.

FIG. 6 is a sectional view of a first cylinder block.

FIG. 7 is a cross-sectional view of a second cylinder block.

FIG. 8 is a schematic diagram for explaining the invention according to claim 4 of the present invention.

[Explanation of symbols]

1: First housing 2: 1st piston 3: First swash plate 4: 1st cylinder block 5: Operation piston 6,6a, 6b: Connecting rod 7: Intermediate 8: 1st shaft 9: Control valve 10: Coupling 11: Second shaft 12: 2nd cylinder block 13: Return spring 14: Bias piston 15: Second piston 16: Second housing 17: Second swash plate 18: Suction flange 19: Discharge flange 20: Piston hole 21: Suction passage 22: Discharge passage

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3H070 AA01 BB04 BB23 CC03 CC21                       DD42 DD55                 3H071 AA03 BB01 BB12 BB13 BB15                       CC23 CC25 DD89                 3H075 AA05 BB03 CC03 CC17 CC33                       CC35 DB27 DB50

Claims (4)

[Claims] 1. A swash plate type double variable displacement axial piston pump in which a first pump and a second pump are coaxially opposed to each other via an intermediate body and are operated by one drive source. An operation piston for operating the first swash plate according to a control command from the outside is brought into contact with an upper part of the first swash plate built in the, and the lower part of the first swash plate is slidable in an axial direction. One end surface of the connecting rod held by the contacting member is abutted, the connecting rod extends through the intermediate body to the second pump side, and the other end surface of the connecting rod is built in the second pump. The second variable swash plate, and at least one of a return spring having an initial load and a bias piston is in contact with the upper part of the second swash plate. Type axial piston pump. 2. A suction port of each of the first pump and the second pump communicates with each other inside the intermediate body, and a discharge port of each of the first pump and the second pump communicates with each other inside the intermediate body,
The intermediate body has a common suction port and a common discharge port, which are connected to the outside, respectively.
Variable displacement axial piston pump described in. 3. A first cylinder block incorporated in a first pump and a second cylinder block incorporated in a second pump are mounted on a rotary drive shaft so that the rotational phases of their pistons do not match each other. The dual variable displacement axial piston pump according to claim 1 or 2, which is attached. 4. The dual variable displacement axial piston pump according to claim 1, wherein the connecting rod is divided midway in the axial direction.