JP2000205117A - Hydraulic rotary machine with swash plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a swash plate type hydraulic rotary machine capable of suppressing the vibration and noises effectively without bringing about increase in the weight or the dimension in axial direction. SOLUTION: A ring-shaped vibration damping plate 17 made from laminated damping steel plate having a constant thickness in which a viscoelastic resin having excellent vibration controlling performance is pinched, is installed between a slide plate 13 admitting sliding thereon of a shoe 10 mounted at the protrusive end of a piston 7 fitted in each cylinder 6 in such a way a capable of sliding in reciprocations and a flat surface 121 to form the bottom surface in cylindrical recess of a swash plate 12, and thereby vibrations and noises in the transmitting path leading from the piston 7 are suppressed effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate type hydraulic rotary machine such as a variable displacement type swash plate type piston pump generally used as a hydraulic source of a hydraulic drive circuit.

[0002]

2. Description of the Related Art A variable displacement type swash plate type piston pump generally used as a hydraulic source of a hydraulic drive circuit has a structure shown in FIG. 3 (described in Japanese Patent Application Laid-Open No. 10-176652). ing. That is, in the piston pump, a rotary shaft 4 and a cylinder block 5 slightly slidable only in the axial direction are provided in a stepped cylindrical space formed in the housing body 2 of the housing 1. A plurality of cylinders 6 are bored around the rotation shaft 4 of the cylinder block 5 in parallel with the rotation shaft 4, and a piston 7 is slidably reciprocated in the cylinder 6. It is inserted. Further, a pair of cylinders 21 and 22 are bored in the upper and lower portions of the step portion of the stepped cylindrical space portion, and the first and second tilt control pistons 14 and
Reference numeral 15 is inserted so as to slide and reciprocate. And
A swash plate 12 having a step abutting on the protruding ends of the first and second tilt control pistons 14 and 15 and a shallow cylindrical recess having a smooth bottom inside the step. It is slidably supported by a tilting support member 16 having excellent wear resistance attached to a closing plate 3 for closing a stepped cylindrical space portion of the body main body 2. It is arranged to be rotatable around.

An annular sliding plate 13 made of a hard metal having excellent wear resistance and having a fixed thickness is fixed to the bottom of the cylindrical concave portion of the swash plate 12. A small disk-shaped shoe 10 is slidably provided in contact with the protruding end of the piston 7 in contact therewith. A plurality of round holes into which the protruding end of the piston 7 is loosely fitted are inscribed on the inner surface of the shoe 10 and an annular shoe pressing plate 11 formed around the rotating shaft 4 is pressed against the swash plate 12 side. A substantially disc-shaped switching valve plate 8 is disposed at the bottom of the stepped cylindrical space in sliding contact with the inner end of the cylinder block 5. An oil passage opening at the inner end is formed in the cylinder block 5 behind the cylinder 6, and the opening of the oil passage is formed by a supply / drain part that is partially formed in the outer surface of the switching valve plate 8 in the circumferential direction. It can communicate with the oil gutter. The oil supply / discharge groove communicates with one of the oil supply / discharge passages 23 and 24. The pair of cylinders 21 and 22 are connected to a pilot hydraulic circuit (not shown), and the amount of projection of the first and second tilt control pistons 14 and 15 is controlled by introducing pilot pressure according to the operation of the operator. In response, the inclination of the swash plate 12 in the vertical direction, that is,
The tilt amount is controlled.

On the other hand, the rotating shaft 4 is connected to a prime mover via a power transmission mechanism (not shown), and is driven to rotate by the prime mover. When the shoe 10 mounted on the protruding end of the piston 7 slides and the swash plate 12 slides with the rotation of the rotation shaft 4, the piston 7 periodically reciprocates in the rotation shaft 4 direction. . Since positive and negative load pressures are applied to the pressure oil in the cylinder 6 in accordance with the reciprocation of the piston 7, when the oil path behind the cylinder 6 is connected to the oil supply / discharge oil paths 23 and 24, Oil drain 23,
The pressure oil is sucked and discharged from 24. The inclination of the shoe 10 is determined by the amount of inclination of the swash plate 12, that is, the amount of tilt. The greater the amount of tilt, the greater the reciprocating movement distance of the piston 7, and accordingly, the suction or cylinder into the cylinder 6 6, the flow rate of the pressure oil discharged from the inside increases.

In the variable displacement type swash plate type piston pump having the above structure, the passage between the oil passage behind the cylinder 6 and the supply / discharge oil groove of the switching valve plate 8 becomes disconnected as the rotation shaft 4 rotates. There is time, but during that time piston 7
, Keeps moving in the direction of the rotating shaft 4, so that the hydraulic pressure in the cylinder 6 is rapidly increased or decreased. Therefore,
When the two oil passages communicate with each other after the non-conduction time has passed, vibration or impact noise is generated due to discharge or rush of the pressure oil into the hydraulic circuit. Such a periodically generated impulsive sound causes mental fatigue to nearby workers, and there is a possibility that a work-related accident such as hearing loss may occur.

In order to solve such a problem, Japanese Patent Laid-Open Publication No. Hei 6-26444 discloses that the back side of a swash plate is supported on the inner bottom of a housing via a thrust bearing and a cushion plate made of a damping steel plate. Discloses a swash plate type pump motor in which the reaction force of the piston is absorbed and alleviated to suppress the generation of vibration and noise.

[0007]

However, since the impact force from the piston is transmitted to the swash plate and the thrust bearing without being alleviated, the vibration corresponding to the piston frequency is transmitted to the housing via the above member. Therefore, the expected effect of suppressing vibration and noise cannot be obtained.
Therefore, the rigidity of the swash plate and the housing can be strengthened in order to enhance the effect of suppressing vibration and noise, but these weights increase and the price increases. In addition, since the cushion plate must be accommodated in the inner bottom of the housing, the length of the housing in the drive shaft direction is increased, and the size of the swash plate pump is increased. The present invention provides a swash plate type hydraulic rotary machine that can effectively suppress the generation of vibration and noise without incurring an increase in weight and an increase in axial dimension by solving such a problem in the prior art. The purpose is to do.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a cylinder provided around a rotation axis of a cylinder block which rotates integrally with a rotation axis rotatably supported in a housing. A damping plate that suppresses vibration generated in the supply / discharge path connected to the swash plate is provided between the smooth surface of the swash plate and the shoe mounted on the protruding end of the piston that is slidably reciprocated in the cylinder. Preferably, the damping plate is disposed between a sliding plate fixed to the swash plate, on which the shoe slides, and a smooth surface of the swash plate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a vertical section passing through the center of the rotation axis of the variable displacement swash plate type piston pump according to the present embodiment, and FIG. 2 is a plan view of the swash plate of the piston pump. Those which are the same as or can be regarded as the same as those of the conventional example are denoted by the same reference numerals, and redundant description will be omitted. In these figures, reference numeral 17 denotes a viscoelastic resin which is sandwiched between a smooth surface on the back side of the sliding plate 13 and a smooth surface of the swash plate 12 and has excellent vibration damping properties between two steel plates having a constant thickness. , A closed end and an open end of the housing body 2 respectively, and a cylinder block housing 27 into which the cylinder block 5 is loosely fitted in the stepped cylindrical space. The cave 41 is rotatably supported by a bearing fixed to the closing plate 3 at the other end of the rotating shaft 4 rotatably attached at one end to the closing end 25, and protrudes outwardly to the power transmission mechanism. The protruding ends 81 and 82 connected to the switching valve plate 8 are provided with an eyebrow-shaped supply oil groove and a drain oil groove formed partially in the circumferential direction on the outer surface of the switching valve plate 8, and 83 is formed in the center of the switching valve plate 8. It is an insertion hole for inserting the rotating shaft 4.

Reference numeral 121 denotes a smooth surface forming the bottom of the cylindrical concave portion of the swash plate 12, reference numeral 122 denotes an insertion hole formed in the center of the swash plate 12 for inserting the rotary shaft 4, and reference numeral 123 denotes left and right sides of the insertion hole 122. A pair of legs integrally formed on both sides, the front side forming a part of a smooth surface 121, and 124 projecting toward the back side of the leg 123 in an arc shape with a radius R toward the tilt support member 16. The convex curved surfaces 125 and 126 are contact portions of the swash plate 12 with which the first and second tilt control pistons 14 and 15 always contact.
Reference numerals 1 and 132 denote a smooth surface on which the shoe 10 slides inside the sliding plate 13 and an insertion hole for inserting the rotating shaft 4 formed in the center, respectively. 133 and 134 denote a shoe on which the shoe 10 slides on the smooth surface 131, respectively. Annular trajectory and smooth surface 13 when moving
1 is a smooth surface on the opposite side.

Reference numerals 151 and 161 denote first and second tilt control pistons 14 and 15, respectively.
Coil springs constantly biased to 5, 126 side, 152, 16
2 is an oil chamber formed between the first and second tilt control pistons 14 and 15 in the cylinders 21 and 22, respectively.
Reference numeral 1 denotes an insertion hole formed in the center of the tilt support member 16 for inserting the rotary shaft 4, and 162 denotes a convex curved surface 124 of the swash plate 12 on both the left and right sides of the front insertion hole 161 of the tilt support member 16. A concave curved surface 171 which is curved and depressed in an arc shape having a radius R which is slidably fitted on the shaft 171 is an insertion hole for inserting the rotary shaft 4 formed in the center of the damping plate 17.

As shown in FIG. 2, the swash plate 12 has a substantially cross shape in plan view with the XX line and the YY line orthogonally passing through the center O of the rotating shaft 4 as center lines. , Y-Y line coincides with a straight line connecting the top dead center position and the bottom dead center position of each piston 7. The XX line is the center line of the pair of legs 123. The centers of the first and second tilt control pistons 14 and 15 are located on the line YY. The first and second tilt control pistons 14 and 15 move the inside of the cylinders 21 and 22 into contact portions 125 according to the tilt control pressure supplied from the pilot hydraulic circuit to the oil chambers 152 and 162 in the cylinders 21 and 22. , 126, and transmits the tilting driving force to the abutting portions 125, 126 of the swash plate 12 that abut.

Accordingly, the swash plate 12 tilts in the directions of arrows A and B in FIG. 1 along the sliding contact surface between the convex curved surface 124 of the leg 123 and the concave curved surface 162 of the tilt support member 16. I do.
When the swash plate 12 is tilted and driven in the direction of arrow A, the tilt angle increases, and the maximum expansion and contraction amount of each piston 7 increases, that is, the capacity of the variable displacement swash plate type piston pump increases. vice versa,
When the swash plate 12 is tilted and driven in the direction of arrow B, the tilt angle becomes small, and the pump capacity decreases.

Next, the operation of this embodiment will be described. When the prime mover rotates and rotates the rotating shaft 4 that is linked thereto, the cylinder block 5 rotates integrally with the rotating shaft 4 together with each piston 7. At this time, the shoe 10 mounted on the protruding end of each piston 7 slides on the smooth surface 121 of the swash plate 12 to draw an annular trajectory 133 shown in FIG. The pistons 7 are guided by the shoes 10 to reciprocate in the respective cylinders 6. When the piston 7 is in the ascending process, the pressure oil suction process is performed, and when the piston 7 is in the descending process, the pressure oil discharging process is performed.
That is, when the piston 7 rotates upward along the annular trajectory 133 from the upper dead center position located on the lower side to the lower dead center position located on the upper side, the cylinder 6 is supplied with the supply oil via the supply oil groove 81. The piston 7 follows a suction step of sucking pressure oil from the supply oil passage 24 by the extension operation of the piston 7 along the annular trajectory 133 from the bottom dead center position to the top dead center position. When the cylinder 6 rotates, the cylinder 6 communicates with the discharge oil passage 23 through the discharge oil groove 82, and follows the discharge step of discharging the pressure oil in the cylinder 6 to the discharge oil passage 23 by the contraction operation of the piston 7. Then, at the top dead center position and the bottom dead center position, the cylinder 6 is in a disconnected state in which it does not communicate with any of the supply oil groove 81 and the discharge oil groove 82.
The pressure oil confined in the cylinder 6 is compressed by the contraction operation of the piston 7 to a high pressure state,
As soon as the high pressure oil communicates with the discharge oil passage 23 through the discharge oil groove 82, high-pressure hydraulic oil is vigorously discharged into the discharge oil passage 23. At this time, a sudden pressure fluctuation occurs in the cylinder 6, and large vibration and noise are generated. Assuming that the order component is N, as a result, a vibration excitation force having a frequency of the piston fundamental frequency (= N × the number of pistons × the number of pump revolutions / 60) and its harmonic component is generated. However, in the present embodiment, since the damping plate 17 made of a damping steel plate is disposed on the back side of the sliding plate 13, the vibration and noise generated by the exciting force of the piston 7 are reduced by the damping plate 17. Since the swash plate 12 resonates significantly, the vibration and noise transmitted from the piston 7 are not transmitted to the swash plate 12 and the tilt support member 16 without the resonance of the swash plate 12 and the vibration being enhanced by the inertia of the swash plate 12. Through the closing plate 3
Transmission to the side can be effectively suppressed.

As described above, in this embodiment, the vibration damping plate 17 is disposed on the back surface side of the sliding plate 13 closest to the piston 7 in the transmission path from the piston 7 where vibration and noise are most easily transmitted. The vibration and noise can be most effectively suppressed without increasing the weight or increasing the axial dimension. In the present embodiment, the case where the present invention is applied to a variable displacement swash plate type piston pump has been described.
The present invention can be similarly applied to a variable displacement swash plate type hydraulic motor. Further, in the present embodiment, the case where the damping steel plate is used as the damping plate 17 has been described.
The sole surface of the shoe 10 and the swash plate 12 is made of the elastic resin plate alone.
1 may be provided.

[0016]

As described above, according to the first aspect of the present invention, there is provided a damping plate for suppressing vibration generated in a hydraulic circuit connected to a cylinder formed in parallel with a rotation axis of a cylinder block. Because it is arranged between the shoe that slides directly or indirectly and the smooth surface of the swash plate, it is arranged to be reciprocally slidable in the cylinder without increasing the weight or increasing the axial dimension. Vibration and noise transmitted from the piston that has been transmitted can be effectively suppressed from being transmitted to the housing. According to the second aspect of the present invention, since the shoe directly slides, the damping plate is disposed between the sliding plate fixed to the swash plate and the smooth surface of the swash plate. The wear of the product can be prevented from being worn by sliding, and the use deterioration of the product can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a vertical cross section passing through the center of a rotating shaft of a variable displacement swash plate type piston pump according to an embodiment of the present invention.

FIG. 2 is a plan view of a swash plate of the piston pump.

FIG. 3 is a cross-sectional view of a vertical cross section passing through the center of a rotation axis of a variable displacement swash plate type piston pump according to a conventional example.

[Explanation of symbols]

 Reference Signs List 1 housing 2 housing main body 3 closing plate 4 rotating shaft 5 cylinder block 6, 21, 22 cylinder 7 piston 8 switching valve plate 10 shoe 11 shoe holding plate 12 swash plate 13 sliding plate 14 first tilt control piston 15th 2 Tilt control piston 16 Tilt support member 17 Vibration control plate 23 Drain oil passage 24 Supply oil passage 27 Cylinder block storage cavity 81 Supply oil groove 82 Drain oil groove 121 Smooth surface 123 Leg 124 Convex curved surface 125, 126 Contact Part 162 concave curved surface

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shigetaka Nakamura 650, Kandamachi, Tsuchiura-shi, Ibaraki F-term in the Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. (Reference) 3H070 AA01 BB04 CC01 DD32

Claims (2)

[Claims] 1. A housing, a rotating shaft rotatably supported in the housing, a cylinder block rotating integrally with the rotating shaft, and a plurality of cylinders drilled around the rotating shaft. A piston disposed reciprocally slidably in the cylinder, and a shoe mounted on a protruding end of the piston;
A swash plate having a smooth surface on which the shoe slides directly or indirectly and rotatably supported around a rotation axis intersecting with the rotation axis, wherein the swash plate is controlled by a tilt control mechanism. In the swash plate type hydraulic rotating machine configured to control the inclination of the swash plate, a vibration suppression plate for suppressing vibration generated in a supply / discharge path connected to the cylinder is provided between the smooth surface of the swash plate and the shoe. A swash plate type hydraulic rotary machine, which is disposed in a swash plate type. 2. The swash plate according to claim 1, wherein the damping plate is disposed between a sliding plate fixed to a swash plate on which a shoe slides directly and a smooth surface of the swash plate. Plate type hydraulic rotary machine.