JP3574196B2 - Hydraulic piston pump motor - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to means for reducing vibration and noise of a swash plate type hydraulic piston motor used as a pump or a motor in a hydraulic device of a construction machine or a general industrial machine.
[0002]
[Prior art]
BACKGROUND ART Conventionally, hydraulic piston pumps 1 as shown in FIG. 6 have been widely used for hydraulic devices of construction machines and general industrial machines. Such a hydraulic piston pump 1 is a variable displacement axial pump having a swash plate 3 inclined with respect to the drive shaft 2, and changes the inclination angle of the swash plate 3 with respect to the drive shaft 2 to change the capacity of the pump. Can be changed. The hydraulic piston pump 1 rotates as a hydraulic actuator and can operate as a motor if hydraulic oil is press-fitted into the suction side.
[0003]
The operation as a pump is performed by a piston 5 that can reciprocate in bores formed at intervals in a circumferential direction of a cylinder block 4 that is rotationally driven by a drive shaft 2. The tip of the piston 5 is pressed against the surface of the swash plate 3 via the slipper 6. The tilt angle of the swash plate 3 is controlled by a servo piston 7. When the drive shaft 2 is driven to rotate, the cylinder block 4 is also driven to rotate. The piston 5, whose tip is pressed against the surface of the swash plate 3 by the slipper 6, reciprocates in a bore formed in the cylinder block 4 according to a change in the distance between the surface of the swash plate 3 and the surface of the cylinder block 4. Do. The drive shaft 2 is supported by a bearing 2a.
[0004]
A valve plate 8 is provided on the other end side of the cylinder block 4, and with the rotation of the cylinder block 4, the respective bores are sequentially moved to the suction side and the discharge side of the hydraulic oil via an oil passage formed in the valve cover 9. Connecting. When the piston 5 moves in the bore and the piston moves toward the swash plate 3 to increase the volume of the space in the bore, hydraulic oil is sucked. Hydraulic oil is discharged at the timing when the piston moves toward the valve plate 8 and the volume of the space in the bore decreases. Such a swash plate type axial pump is housed in a casing 10 and connected to a drive source via a shaft coupling 11.
[0005]
The hydraulic piston pump 1 is mounted on the bracket 12 by mounting bolts 13. The bracket 12 is fixed by a mounting bolt 16 to an apparatus body 15 on which a common base plate 14 serving as a gantry is provided.
[0006]
In recent years, construction machines and general industrial machines have also been required to reduce vibration and noise. Among the devices that make up a hydraulic device, a piston pump is a major source of vibration and noise. The propagation path of the natural vibration of the pump is, in the hydraulic piston pump 1 of FIG. 6, in the order of the pump 2 → the bracket 12 → the common base plate 14 → the apparatus main body 15.
[0007]
Since the device body 15 has a large area, the vibration and noise generated from the hydraulic piston pump 1 may be further increased and may be a secondary source of vibration and noise larger than the pump itself. Further, when a vibration resonance phenomenon is accompanied, the vibration and noise become more harmful.
[0008]
As a prior art for suppressing such vibration and noise, there is, for example, Japanese Utility Model Laid-Open No. 2-115975. In this prior art, a vibration isolating structure made of an elastic body such as rubber is formed in a portion where a pump is mounted. Also in FIG. 6, the concept of the prior art is applied, a vibration isolating rubber 17 and a vibration isolating ring 18 are provided, and a position between the hydraulic piston pump 1 and the bracket 12 is set as close to the hydraulic piston pump 1 as a vibration source. A vibration isolating structure is formed in the motor to prevent the propagation of vibration from the pump and the generation of secondary vibration.
[0009]
[Problems to be solved by the invention]
The vibration isolating structure using the vibration isolating rubber 17 and the vibration isolating ring 18 in FIG. 6 uses an expensive material, and thus increases the manufacturing cost of the hydraulic device and the like. Further, even if the propagation of vibration can be prevented by the vibration-proof structure, the vibration of the hydraulic piston pump itself is not suppressed, and the shaft coupling 11 and the piping are required to have flexibility to allow vibration. For this reason, it is necessary to use expensive hoses with a finite life, which further increases the cost as a hydraulic device. Further, since an elastic body such as the vibration isolating rubber 17 must be used, the life of the hydraulic device is shortened and its reliability is reduced due to its durability and aging. Further, since the vibration isolating structure must be formed when the pump is mounted, the mounting work is troublesome and the bulk of the mounting portion is increased.
[0010]
An object of the present invention is to provide a hydraulic piston pump motor that can achieve low vibration and low noise without using a vibration isolation structure.
[0011]
[Means for Solving the Problems]
The present invention provides a cylinder block in which a plurality of bores parallel to the rotation axis are formed at equal intervals in a circumferential direction,
A plurality of pistons that can reciprocate axially in each bore of the cylinder block;
A swash plate that is arranged on one end side in the rotation axis direction of the cylinder block, the tip of each piston is pressed, and is inclined with respect to the rotation axis of the cylinder block,
A pair of swash plate type hydraulic pump motors, which are arranged on the other end side in the rotation axis direction of the cylinder block and supply or discharge hydraulic oil to or from each bore, are provided.
In the pair of swash plate type hydraulic pump motors, in a double pump of a symmetric tandem type structure in which the valve plate sides are connected by a valve block, the positions of the top and bottom dead centers are matched, and the rotating shafts are connected by a joint,
The cylinder block and the rotary shaft and the rotary shaft and the joint are connected by splines formed at equal intervals in the circumferential direction, and the number of splines of each spline connection and the number of bores of the cylinder block are mutually different. Are in prime relation,
A hydraulic piston pump motor characterized in that the cylinder block and the rotating shaft and the rotating shaft and the joint are connected so that the phases of the reciprocating motions of the pistons in the respective cylinder blocks match.
[0012]
[Action]
As a study to reduce the vibration and noise of hydraulic pumps, the vibration and noise generated by the swash plate type hydraulic pump were measured, analyzed and examined, and as a result, strong sound was radiated from the rear part, that is, the end face on the valve plate side, and the cause Was found to be because the whole pump vibrated rigidly in the axial direction in the same phase as the gantry.
[0013]
As a vibration model of a swash plate type hydraulic pump, as shown in FIG. 7, a pump and a gantry can be simulated in a four-mass system. M _CF , M _P , M _C , and M _CR represent the mass of the front part of the pump casing, the mass of the piston and the drive shaft, the mass of the cylinder, and the mass of the rear part of the pump casing, respectively. K _P and C _P represent the spring constant and the damping constant of the rolling bearing of the drive shaft, respectively. K and C represent a spring constant and a damping constant between the piston and the cylinder, respectively. C _C represents a damping constant between the piston and the valve plate. K _{B, K C} represents respectively a spring constant of the bracket and the pump casing. _{I F, I P, I C} , I R denotes a pump casing front, the piston and the drive shaft, a cylinder, and the vibration intensity of the pump casing rear. F represents pressure pulsation.
[0014]
FIGS. 8 and 9 show the results of a vibration analysis performed by a computer based on the simulation of FIG. FIG. 8 shows the pressure pulsation applied between the piston and the cylinder. FIG. 9 shows an analysis value of the simulation result as a broken line and an actual measurement value as a solid line with respect to the vibration acceleration, and it can be seen that these results are almost the same.
[0015]
From these analysis results, (1) the pump support system is asymmetric, so that when the internal force due to pressure pulsation acts on the piston and cylinder, this rigid body vibration is excited. (2) The main acoustic radiation of the pump is reduced. First, it is necessary to reduce the pressure pulsation first, and (3) the rigidity of the support portion of the pump also has an important meaning.
[0016]
The present invention has been devised based on the above analysis results, and uses a symmetrical tandem pump and matches the phases of the pumping actions of the front and rear pumps, thereby canceling internal rigid body vibration and reducing noise. Things.
[0017]
According to the present invention, a tandem type structure in which a pair of swash plate hydraulic pump motors are connected to each other on the valve plate side and connected by a valve block so that the positions of the top and bottom dead centers of the reciprocating motion of the piston in the cylinder block coincide. In this double pump, the rotating shafts are connected so that the phases of the reciprocating motions of the pistons in the respective cylinder blocks match. When the rotating shafts are connected, they can be adjusted in small steps by meshing the splines. As a result, the generated vibrations are in opposite directions, and cancel each other out. Therefore, low vibration and low noise can be achieved, and propagation of vibration and generation of secondary vibration can be prevented without using a vibration isolating structure.
[0018]
According to the invention, when the suction and discharge ports are merged and the pair of hydraulic pump motors externally operate as one hydraulic pump motor, the pair of hydraulic pump motors operate under the same conditions. Vibrations and noises generated by the respective hydraulic pump motors can be made almost equal, and the generation of vibrations and noises to the outside can be remarkably suppressed by canceling each other.
[0019]
【Example】
FIG. 1 shows a configuration of a hydraulic pump 20 according to one embodiment of the present invention. The hydraulic pump 20 is formed by connecting the front pump 21a and the rear pump 21b in common with the axis of the drive shaft 22 and serially connecting the front and rear. The configurations inside the front pump 21a and the rear pump 21b are basically the same. Corresponding portions have the same reference characters allotted, and are distinguished by the suffixes a and b. When referring to components in general, only reference numerals are used.
[0020]
Both the front pump 21a and the rear pump 21b are variable displacement axial pumps. A swash plate 23 a is provided to change the capacity, and is inclined with respect to the drive shaft 22. Cylinder blocks 24a and 24b are provided on the axis of the drive shaft 22. A plurality of bores are formed in the cylinder block 24a at intervals in the circumferential direction, and a piston 25a can reciprocate in each bore in an axial direction parallel to the axis of the drive shaft 22. The tip of the piston 25a is pressed against the surface of the swash plate 23a via the slipper 26a. The inclination angle of the swash plate 23a is controlled by a servo piston 27a forming a regulator.
[0021]
Supply and discharge of hydraulic oil into and from the bores of the cylinder blocks 24a and 24b are performed via valve plates 28a and 28b, respectively. Hydraulic oil is supplied to or discharged from the valve plates 28a and 28b via a valve block 29. The front pump 21a and the rear pump 21b are configured in casings 30a and 30b, respectively.
[0022]
The front pump 21a and the rear pump 21b are interconnected by a pump joint 31. The hydraulic pump 20 as a whole is mounted on a bracket 32 via mounting bolts 33. The bracket 32 is fixed by a mounting bolt 36 to a device main body 35 such as a hydraulic device on which a common base plate 34 is provided. The rotation shafts 38a and 38b of the front pump 21a and the rear pump 21b to which the pump joint 31 is connected are provided with splines as described later, and the rotation phase can be adjusted.
[0023]
FIG. 2 shows a state of splines provided on the rotating shaft 38 and the cylinder block 24. As shown in FIG. 2A, a male spline 40 connected to the cylinder block 24 and a male spline 41 connected to the pump joint 31 are formed on the rotating shaft 38. As shown in FIG. 2B, a plurality of bores 42 are formed in the cylinder block 24 at intervals in the circumferential direction. At the center, a female spline 44 corresponding to the male spline 40 of the rotating shaft 38 is formed. The male spline 40 of the rotating shaft 38 is fitted to the female spline 44 of the cylinder block 24. The male spline 41 of the rotating shaft 38 is fitted to a female spline formed on the pump joint 30. Each of the pumps 21a and 21b is processed by adjusting the phase of each spline to a single cylinder bore 42, and the pumps 21a and 21b are assembled by aligning the positions of the bore 42 holes. The phase of the reciprocating motion of the piston 25 can be matched. Further, even when the phase of the spline processing is arbitrarily processed, the phase can be adjusted by the following method.
[0024]
In this embodiment, nine bores 42 are formed at regular intervals, 20 male splines 40 and female splines 44 are formed at regular intervals, and 17 male splines 41 are formed at regular intervals. These numbers 9, 20, and 17 have a prime number relationship that does not have a common divisor, and the phase of the front pump 21a and the rear pump 21b is precisely adjusted by changing the engagement of the pump joint 31 and the cylinder block 29. be able to. That is, since the number of teeth of the spline is 20 and 17, the phase can be adjusted in steps of 0.118 ° of a quotient obtained by dividing 40 ° of one cycle by 20 × 17 = 340. For example, as shown in FIG. 2B, when the positions of the bore 42 and the spline groove 44 are aligned at the uppermost portion, the phase difference between the ninth female spline 44 and the fourth bore 42 in the clockwise direction is obtained. Is 3.636 °, and the phase difference of the spline groove 44 with respect to the bore 42 can be adjusted by this step. The phase difference between the clockwise third spline groove 41 shown in FIG. 2A and the clockwise second bore 42 shown in FIG. 2B is 2.000 °. The phase difference can be adjusted based on this reference. By combining both adjustments, the phase difference can be adjusted in units of 0.118 ° as described above.
[0025]
FIG. 3 shows a passage of hydraulic oil formed inside the cylinder block 29 of FIG. Hydraulic oil sucked from the common suction port 50 branches into suction passages 51a and 51b and is set on the valve plates 28a and 28b, respectively. The hydraulic oil delivered from the valve plates 28a and 28b is discharged from the discharge paths 52a and 52b, respectively. The hydraulic oil discharged from the separate outlet ports 52a and 52b can be used for different purposes.
[0026]
FIG. 4 shows a configuration of a valve block 59 according to another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIG. 1 and corresponding parts are denoted by the same reference numerals. It should be noted that the discharge paths 52a and 52b join the common discharge port 60. If the valve block 59 is used, the front pump 21a and the rear pump 21b externally operate as an integrated pump, and operating conditions such as the discharge pressure are the same. For this reason, the vibrations generated from the cylinder blocks 24a and 24b are almost the same, and only the directions are reversed, so that they can cancel each other and the generation level can be abnormally reduced.
[0027]
FIG. 5 shows the concept of phase matching according to the embodiment of FIG. As shown in FIG. 5A, the discharge pressure of the front pump 21a fluctuates every 40 degrees of rotation of the drive shaft 22 because nine bores 42 are formed at equal intervals. As shown in FIG. 5 (2), if the discharge pressure of the rear pump 21b has a phase delay of x degrees compared to the discharge pressure of the front pump 21a, the phase is advanced by the adjustment for shifting the meshing position of the spline. Thus, the vibrations of the cylinder blocks 24a and 24b are canceled each other, and the vibration and noise transmitted to the outside can be reduced. In each of the above embodiments, the hydraulic pump 20 has been described. However, the swash plate type hydraulic pump can also be used as a rotary actuator such as a hydraulic motor. Occurrence can be reduced.
[0028]
Further, a fixed capacity type in which the inclination angle of the swash plate 23 is fixed may be used.
[0029]
【The invention's effect】
As described above, according to the present invention, a pair of swash plate type hydraulic piston motor pumps are opposed to each other in the axial direction, and the angle at which the rotating shafts are connected is adjusted in small increments so that the generated vibrations cancel each other. Therefore, the vibration and noise of the hydraulic piston pump itself can be reduced. Thus, when the hydraulic piston pump motor of the present invention is mounted on a hydraulic device or the like, the axial vibration can be sufficiently reduced without providing a vibration isolating structure. Since no vibration isolating structure is provided, there is no reduction in the life or reliability due to a rubber material or the like as a vibration isolating material.
[0030]
In general, when comparing one large-capacity hydraulic pump motor with a pair of half-capacity hydraulic pump motors, using a small-capacity pump increases the manufacturing cost due to mass production effects and the like. It may be reduced. It is well known that a small double pump or the like can operate at a higher speed, so that the weight is smaller than that of a large single pump.
[0031]
Further, according to the present invention, since the pair of hydraulic pump motors operates as a single pump as a whole, the conditions of vibration generation in each hydraulic pump motor match, and the reduction effect due to cancellation can be increased.
[Brief description of the drawings]
FIG. 1 is a partially cutaway front view showing a configuration of an embodiment of the present invention.
FIG. 2 is a side view of a rotary shaft and a cylinder block of the embodiment of FIG.
FIG. 3 is a simplified front view of the valve block of the embodiment of FIG.
FIG. 4 is a simplified front view of a valve block according to another embodiment of the present invention.
FIG. 5 is a graph showing a temporal change of a front pump discharge pressure and a rear pump discharge pressure of the embodiment of FIG. 1;
FIG. 6 is a partially cutaway front view showing a configuration of a conventional hydraulic piston pump.
FIG. 7 is a block diagram showing a four-mass system simulation model for vibration analysis of a swash plate type hydraulic pump.
FIG. 8 is a graph showing an input waveform to the model of FIG. 7;
9 is a graph showing the simulated waveform and the actually measured waveform of FIG. 7 by a broken line and a solid line, respectively.
[Explanation of symbols]
Reference Signs List 20 hydraulic pump 21a front pump 21b rear pump 22 drive shaft 23a swash plate 24a, 24b cylinder block 25a piston 28a, 28b valve plate 29, 59 valve block 31 pump joint 32 bracket 35 device body 38, 38a, 38b rotating shaft 40, 41 male Spline 44 Female spline 42 Bore 50 Common suction port 60 Common discharge port

Claims (2)

A cylinder block in which a plurality of bores parallel to the rotation axis are formed at equal intervals in the circumferential direction;
A plurality of pistons capable of reciprocating in the axial direction within each bore of the cylinder block;
A swash plate that is arranged on one end side in the rotation axis direction of the cylinder block, the tip of each piston is pressed, and is inclined with respect to the rotation axis of the cylinder block,
A pair of swash plate type hydraulic pump motors, which are arranged on the other end side in the rotation axis direction of the cylinder block and include a valve plate for supplying or discharging hydraulic oil to each bore, are provided.
The pair of swash plate type hydraulic pump motors is a symmetrical tandem type double pump in which the valve plate sides are connected to each other by a valve block, the positions of the top and bottom dead centers are matched, and the rotating shafts are connected by a joint.
The cylinder block and the rotary shaft, and the rotary shaft and the joint are connected by splines formed at equal intervals in the circumferential direction, and the number of splines of each spline connection and the number of bores of the cylinder block are mutually different. Are in prime relation,
A hydraulic piston pump motor wherein a connection is made between a cylinder block and a rotating shaft and between a rotating shaft and a joint so that phases of reciprocating movements of pistons in respective cylinder blocks match. Hydraulic oil is supplied to the pair of hydraulic pump motors by branching from a common suction line,
2. The hydraulic piston pump motor according to claim 1, wherein the hydraulic oil discharged from each hydraulic pump motor joins a common discharge pipe.

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