JPH0660631B2 - Hydraulic pressure balance mechanism of piston in piston pump or motor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a piston hydraulic pressure balance mechanism in a piston type pump or motor that can be used in various hydraulic equipment fields and the like.

(B) Conventional technology Pumps or motors used mainly in the field of hydraulic equipment (means a fluid machine that functions as a pump when rotational power is applied and functions as a motor when high-pressure hydraulic oil is input. There are roughly three types of gears: vane type, piston type and piston type, but recently, there is a tendency that piston type pumps are used instead of the gear type pump or vane type pump. It is in. This is because the piston type pump has the advantages that it is highly efficient, the pump size can be changed steplessly, and that it is suitable for high pressure.

By the way, a pump of this type, for example, an oblique shaft type piston pump, has a casing having an inflow / outflow port, a rotating shaft supported by the casing through a bearing, and an inner end portion of the rotating shaft capable of integrally rotating. And a cylinder block having a plurality of cylinder holes rotatably provided around an inclined axis intersecting with the center of rotation of the rotating shaft and parallel to the inclined axis and opened toward the torque plate portion. , A plurality of pistons slidably fitted in the respective cylinder holes of the cylinder block and connected to the torque plate directly or via connecting rods. However, in the conventional type, since the hydraulic pressure acting on the piston is not balanced, there is a circumstance that a tilting moment acts on the piston, and the outer peripheral surface of the piston is strongly pressed against the inner peripheral surface of the cylinder hole. A large frictional resistance is generated between the piston and the cylinder. Further, there is also a system in which hydraulic oil is introduced also between the tip of the piston or the connecting rod and the torque plate, but the conventional one is one in which the space between them is simply lubricated with hydraulic oil. Is. for that reason,
If the tip of the piston or the connecting rod is strongly pressed against the pivotal support surface of the torque plate due to the imbalance of the hydraulic pressure acting on the piston, the oil film will be cut off at that part and seizure or mechanical loss will occur. Grows larger. Therefore, the conventional one has a problem that it is difficult to sufficiently improve the mechanical efficiency.

Therefore, recently, in the piston pump or motor as described above, a pressure pocket into which a working fluid is introduced is formed between the outer end of the piston and the torque plate, and the working fluid in the pressure pocket is transferred to the piston. Is substantially balanced with the force for pushing the piston toward the torque plate side by the working fluid in the pump chamber, and the mechanical efficiency of the pump is significantly improved. Something like this is considered. However, in this type of pump, the axis of the cylinder block is inclined by a certain angle θ with respect to the center of rotation of the torque plate, and the inclination of the piston with respect to the torque plate is within a certain range (about 2θ).
In the inside, it changes periodically with the rotation of the torque plate. Therefore, if the pressure pocket is formed only by forming the concave portion in the spherical surface seat of the torque plate, the hydraulic oil in the pressure pocket exerts a force for pressing the outer end of the piston in the axial direction of the piston. Difficult to keep constant. On the other hand, the force with which the hydraulic oil in the pump chamber presses the inner end of the piston in the axial direction is constant as long as the pressure of the hydraulic oil does not change. Therefore, it is extremely difficult to always keep the hydraulic pressure acting on the piston in a constant state by the usual method of forming the pressure pocket by forming the recessed portion in the seat.

(C) Objective The present invention has been made in view of such circumstances.
It is an object of the present invention to provide a piston hydraulic pressure balance mechanism in a piston pump or a motor, which enables a pressure of the working fluid acting on the piston to be substantially balanced at all times with a simple configuration.

(D) Structure In order to achieve the above object, the present invention has a piston pump or motor as described above, that is, a piston pivotally supporting member such as a torque plate, and a cylinder hole opened in the direction of the piston pivotally supporting member. A cylinder block is arranged so as to face each other, a piston is slidably fitted in the cylinder hole, and an outer end of the substantially spherically shaped piston is pivotally supported on a spherical seat of the piston pivot member. In a piston pump or motor configured so that the volume of the pump chamber formed in the cylinder hole can be increased or decreased in accordance with the relative contact / separation operation of the piston pivotally supporting member and the cylinder block, A notch portion having substantially the same diameter as the inner diameter of the cylinder hole is provided at one end to form a pressure pocket between the notch portion and the spherical seat. , The pressure pocket communicates with the pump chamber via a fluid passage, and the working fluid in the pressure pocket presses the piston toward the cylinder block, and the working fluid in the pump chamber causes the piston to move the piston pivotally. It is characterized in that it is configured to be able to substantially balance the force pressing in the supporting member direction.

(E) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of a piston pump or a motor according to the present invention, in which 1 is a casing. The casing 1 is composed of a cylindrical front cover portion 2 and a rear cover portion 3 which is liquid-tightly attached to the rear end opening of the front cover portion 2. The rear cover portion 3 has a pair of outflows. The inlet ports 4 and 5 are opened. The rotary shaft 6 is housed in the casing 1. Rotating shaft 6
Is for input or output and is supported by the casing 1 via a first bearing 7 and has an outer end 6a.
Through the opening 2a provided in the front cover portion 2 to the outside. Further, a spline groove engraved portion 6b is provided in a portion of the rotary shaft 6 located inside the casing 1, and a torque plate 8 as a piston pivotal support member is fitted in the spline groove engraved portion 6b. The torque plate 8 has a disc shape and rotates together with the rotary shaft 6. A cylinder block 9 is arranged behind the torque plate 8. The cylinder block 9 is a thick cylindrical body provided rotatably around an inclined axis L that is inclined by a constant angle θ with respect to the rotation center M of the torque plate 8 and the rotation shaft 6, In this case, the rear end surface of the inclined cylinder 12 is slidably contacted with the valve surface 11 formed on the rear cover portion 3 and is rotatably fitted to the outer periphery of the inclined cylinder 12 planted in the rear cover portion 3.
Further, the cylinder block 9 is provided with a plurality of cylinder holes 13 which are parallel to the tilt axis L and open in the direction of the torque plate 8 at equal angular intervals in the circumferential direction.
A piston 14 is slidably fitted in each of the cylinder holes 13. Piston 14
Piston body 15 fitted in the cylinder hole 13
And a rod portion 16 extending outward from the piston main body portion 15 are integrally formed.
A proper clearance (about 0.05 mm) on the inner circumference of the cylinder hole 13
It is provided with a fitting portion 17 that is fitted via a piston ring 19 provided between the fitting portion 17 and the pressing plate 18. The tip of the rod portion 16, that is, the outer end 14a of the piston 14 is formed in a spherical shape, and the outer end 14a is pivotally supported by the torque plate 8. Specifically, the same number of spherical seats 21 as that of the pistons 14 are provided on one end surface of the torque plate 8 at equal angular intervals in the circumferential direction, and the spherical seats 21 of the pistons 14 are attached to the spherical seats 21. The outer end 14a is rotatably fitted. The piston retainer 22 prevents the pistons 14 from coming off the torque plate 8. Further, a synchronizing mechanism 23 is provided between the torque plate 8 and the cylinder block 9, and the inner end 14b of each piston 14 is accompanied by the synchronous rotation of the torque plate 8 and the cylinder block 9. The volume of the pump chamber 24 formed on the side is increased or decreased. As shown in FIG. 1, the synchronizing mechanism 23 comprises a ring member 25 having an annular mounting portion 25a at the base end and an inward tooth 25b at the distal end. It is fitted and fixed to the inner circumference of the block 9 and the inward teeth 25b are attached to the spline groove 6b.
It meshes with the rear end of the. The pump chamber 24 is a chamber formed by the piston body 15 of the piston 14 and the cylinder hole 13, and is opened to the rear end surface of the cylinder block 9 via a fluid passage 27. Further, connection ports 28 and 29 communicating with the respective inflow / outflow ports 4 and 5 are opened on the valve surface 11 of the casing 1 which slides on the rear end surface of the cylinder block 9. The connection port 28 communicating with one of the inflow and outflow ports 4 is located in the region I on the right side in FIG. 3 of the virtual dividing plane N including the rotation center M of the torque plate 8 and the tilt axis L in the pump chamber 24. And the connection port 29 communicating with the other inflow / outflow port 5 is formed in a semi-circular shape so as to communicate with the pump chamber 24 existing in the region II on the left side of the virtual dividing surface N. ing.

In this piston pump or motor, the fitting length t of the piston 14 with respect to the cylinder hole 13 is 1.
Set a small value of about 0 mm and set the tilt angle θ
Is set to 15 ° or less, preferably about 10 °.

The inner end 6b of the rotary shaft 6 extends through the torque plate 8 and the cylinder block 9 to the rear cover portion 3 of the casing 1, and the extended end is provided on the rear cover portion 3. It is supported by the second bearing 31.

Further, in this piston or motor, the first pressure pocket (the connection port 28) is provided between the valve surface 11 and the cylinder block 9, and the outer end 14a of the piston 14 and the torque plate 8 are provided. A second pressure pocket 32 is formed between the first pressure pocket 32 and the second pressure pocket 32, and a working fluid in the pump chamber 24, for example, through a fluid passage 33 formed in the axial center of the piston 14 in the second pressure pocket 32.
A part of hydraulic oil is introduced. Then, the hydraulic oil in the first pressure pocket 28 presses the cylinder block 9 toward the torque plate 8 and the hydraulic oil in the pump chamber 24 presses the cylinder block 9 toward the valve surface 11. The force is approximately balanced, and the hydraulic oil in the second pressure pocket 32 presses the piston 14 toward the cylinder block 9 and the hydraulic oil in the pump chamber 24 moves the piston 14 in the torque plate 8 direction. It almost balances the force of pressing.
More specifically, the opening width w _{1 of the one} connection port 28 forming the first pressure pocket and the valve surface 1 are described.
By setting the width w ₂ of the sliding contact surface portion between the cylinder block 9 and the cylinder block 9 to an appropriate value, the force F ₁ of the hydraulic oil pressing the rear end surface of the cylinder block 9 is set to a desired value. It should be noted that the hydraulic oil in each of the pump chambers 24 has a force F _{2 that} presses the cylinder block 9 toward the valve surface 11.
Is transiently changed when the pump chamber 24 and the connection port 28 are connected and disconnected, and the number of pump chambers 24 connected to the connection port 28 is changed from four to five,
It also changes from 5 to 4. Therefore, the resultant force of the force F ₂ that the hydraulic oil in the pump chamber 24 communicating with the connection port 28 presses the cylinder block 9 toward the valve surface 11 changes periodically (about 1.5% in the illustrated example). However, in this embodiment, the average value of the resultant force and the force F ₁ are set to be balanced (see FIG. 6). On the other hand, the hydraulic balance for the piston 14 is as follows. That is, the inner diameter D ₁ and substantially the same diameter D ₂ of the cylinder bore 13 to the outer end 14a of the piston 14, the annular groove 34 provided with the annular groove 34, which in the spherical seat 21 communicates The second pressure pocket 32 is formed by the recess 21a provided. Then, the hydraulic oil in the pressure pocket 32 presses the piston 14 toward the cylinder block 9 with a force F _3, and the hydraulic oil in the pump chamber 24 presses the piston 14 toward the torque plate 8 with a force F '. ₂ and ₂ are substantially balanced (see FIG. 7).

Further, in this embodiment, the torque plate 8 is further added.
The surface 36 on the side opposite to the cylinder block is brought into close contact with the pressure receiving surface 37 provided on the casing 1 to form a pressure pocket 38 into which the hydraulic oil in the pump chamber 24 is introduced between the both surfaces 36, 37. The thrust force by which the hydraulic oil in the pocket 38 presses the torque plate 8 and the thrust force acting on the torque plate 8 from the piston 14 side are substantially balanced. Specifically, each spherical seat 2 on the front surface of the torque plate 8
The portion corresponding to 1 is projected in a circular shape, and the protruding surface 36 is brought into close contact with the pressure receiving surface 37 provided on the front cover portion. Further, a pressure pocket 38 having a shape as shown in FIG. 5 is provided on the projecting surface 36, and a part of the hydraulic oil is introduced into the pump chamber 24 through a pressure liquid introduction passage 39 in the pressure pocket 38. There is. The hydraulic oil in the pressure pocket 38 causes the torque plate 8 to move to the piston 1
The force F for pushing in four directions and the thrust direction component F ′ ₃ cos θ of the force F ′ ₃ for pushing the torque plate 8 toward the pressure receiving surface 37 by the hydraulic oil in the pressure pocket 34 are balanced. (See FIG. 8). Reference numeral 41 indicates that the torque plate 8 is constantly abutted on the pressure receiving surface 37 and that the cylinder block 9 is connected to the valve surface 1.
It is a spring that is pressed against 1 with a weak force.

Next, the operation of this embodiment will be described.

For example, the rotating shaft 6 is rotationally driven in the arrow X direction by a motor (not shown) or the like, and the torque plate 8 and the cylinder block 9 are rotated.
When they are synchronously rotated in the same direction, the piston 14 existing in the first region I is successively immersed in the cylinder hole 13 due to the inclination of the tilt axis L, and the piston 14 existing in the second region II is rotated. Are successively projected from the cylinder hole 13. Therefore, the volume of the pump chamber 24 passing through the first region I communicating with the one connection port 4 is reduced, and the volume of the pump chamber 24 passing through the second region II communicating with the other connection port 5 is reduced. Is gradually increased, the hydraulic oil sucked from the inflow / outflow port 5 is introduced into the pump chamber 24 in the second region II, and
The hydraulic oil pushed out from the pump chamber 24 in the region I is discharged from the inflow / outflow port 4.

The pump function is performed as described above. In this pump, an annular groove 34 having a diameter D ₂ substantially the same as the inner diameter D ₁ of the cylinder hole 13 is provided at the outer end 14 a of the piston 14, and the annular groove 3 is provided.
4 and the spherical seat 21, a pressure pocket 32 is formed, and the pressure pocket 32 is communicated with the pump chamber 24 via a fluid passage 33. The hydraulic oil in the pressure pocket 32 causes the piston 14 to move. The force F ₃ for pressing the cylinder 14 toward the cylinder block 9 and the force F ′ ₂ for pressing the piston 14 toward the torque plate 8 by the hydraulic oil in the pump chamber 24 are substantially balanced. for that reason,
Even if the piston tilts with respect to the torque plate, the pressure of the hydraulic oil in the pressure pocket always acts on the entire area of the annular groove 34, and the action direction and the action area of the hydraulic pressure on the piston 14 are It is immutable. Therefore, from the pressure pocket 32 side, the piston 1
It is possible to always keep the oil pressure acting on No. 4 and the oil pressure acting on the piston 14 from the pump chamber 24 side in a constant state. Moreover, since this structure only needs to provide the annular groove 34 at the outer end 14a of the piston 14, it is more difficult than the case in which only the spherical seat 21 is provided with a recess having a complicated shape for always maintaining the hydraulic balance. It has a simple structure and is easy to implement.

Further, since the notch of the outer end 14a of the piston 14 is formed as the ring-shaped annular groove 34, the pressure receiving area for the spherical seat 21 is significantly increased as compared with the case where the outer end 14a is completely cut off, As a result, the breakage of the oil film between the spherical seat 21 and the spherical seat 21 can be prevented as much as possible. Therefore, seizure due to sliding of the pressure receiving portion can be prevented, and the durability of the device is significantly improved. In particular, the effect is great when there is a portion having a small pressure receiving area between the spherical seat 21 and the spherical seat 21, as in the case where the pressure relief groove 35 communicating with the case drain through the passage 8a is provided. Since an oil film is formed in the portion between the outer end 14a and the annular groove 34 that engages with the spherical seat 21, the force pressing the piston 14 in the cylinder direction is the outer peripheral edge of the larger annular groove 34. Proportional to the area of. Therefore, even when the annular groove 34 is provided as the cutout portion, a pressure balance equivalent to that when the outer end 14a is completely cut off can be obtained.

In addition, in the above-described embodiment, the case where the pump is used as a pump has been described, but for example, if a high-pressure working fluid is supplied to the one inflow / outflow port 4, it can also function as a motor.

(F) Effects Since the present invention has the above-described configuration, the piston hydraulic pressure balancing mechanism in the piston pump or the motor can keep the pressure of the working fluid acting on the piston substantially balanced with a simple configuration. Can be provided.

[Brief description of drawings]

1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the line II in FIG. 1, and FIG. 3 is a sectional view taken along the line III-III of FIG. The drawing is an enlarged view showing the piston of the same embodiment, FIG. 5 is a partial sectional view taken along line VV in FIG. 1, and FIGS. 6, 7, and 8 show the pressure balance state in the I region. FIG. 1 ... Casing 4, 5 ... Inflow / outflow port 6 ... Rotating shaft 8 ... Piston pivot member (torque plate) 9 ... Cylinder block 11 ... Valve face, 13 ... Cylinder hole 14 ... Piston, 14a ...... Outer end 24 ...... Pump chamber 32 ...... Pressure pocket 34 ...... Notch (annular groove) 35 …… Pressure release groove, L …… Inclined axis M …… Rotation center

Front page continuation (72) Inventor Kazushige Nakagawa 25, Saiin Oiwake-cho, Ukyo-ku, Kyoto-shi, Kyoto Incorporated company Shimadzu Corporation Gojo factory (72) Inventor Ko Ryo 25 Oiwake-cho, Saiin, Ukyo-ku, Kyoto-shi, Kyoto In-house Shimadzu Gojo Factory (72) Inventor Tadashi Ozeki 25 No. 25, Saiin Oiwake-cho, Ukyo-ku, Kyoto Prefecture In-house Shimadzu Gojo Factory (56) References Japanese Patent Publication Sho 42-20828 (JP, B1) United States Patent 3162142 (US, A) US Patent 3291068 (US, A)

Claims (1)

[Claims] 1. A piston pivotally supporting member and a cylinder block having a cylinder hole opened toward the piston pivotally supporting member are arranged so as to face each other, and a piston is slidably fitted in the cylinder hole and The outer end of the spherically shaped piston is pivotally supported on the spherical seat of the piston pivot member, and the piston pivot member and the cylinder block are moved relative to each other in the cylinder hole. In a piston pump or motor configured to increase or decrease the volume of a formed pump chamber, a ring-shaped annular groove having substantially the same diameter as the inner diameter of a cylinder hole is provided at the outer end of the piston, and the annular groove and the A pressure pocket is formed between the spherical seat and the spherical seat, and the pressure pocket is communicated with the pump chamber through a fluid passage. A piston pump or motor characterized in that the force for pushing the piston in the cylinder block direction and the force for the working fluid in the pump chamber pushing the piston in the direction of the piston pivot member can be substantially balanced. Hydraulic pressure balance mechanism of the piston.