Variable displacement hydraulic rotary machine

Abstract

To make it possible to smoothly discharge drain from a solenoid valve, thereby stabilize an operating pressure, and stably control a variable displacement part.SOLUTION: A regulator casing 21 of a regulator 20 is provided with a regulator drain chamber 21D communicating with a casing drain chamber 6 in the regulator casing 21. A side surface 21B of the regulator casing 21 is provided with an opening part 21E leading to the regulator drain chamber 21D. A valve block 23 of a solenoid valve 22 is provided with a protrusion part 23C protruding from an attachment surface 23A attached to the side surface 21B of the regulator casing 21, and fitted into the opening part 21E. A drain port 24 is provided in the protrusion part 23C so as to be exposed in the regulator drain chamber 21D while the protrusion part 23C is fitted into the opening part 21E.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a variable displacement hydraulic rotary machine that is mounted on a construction machine such as a hydraulic excavator and is used as a variable displacement hydraulic pump or a hydraulic motor.

Background Art

[0002] Generally, a construction machine such as a hydraulic excavator is equipped with a variable displacement hydraulic pump or the like as a power source and a variable displacement hydraulic motor or the like as an operating device. The variable displacement hydraulic pump and the hydraulic motor constitute a variable displacement hydraulic rotary machine. The variable displacement hydraulic rotary machine includes, for example, a casing of a hydraulic rotary machine having a capacity variable portion, a tilting actuator provided on the casing and tilting the capacity variable portion in response to a tilting control pressure (pressure oil) supplied and discharged from the outside, a regulator attached to the casing and variably controlling the tilting control pressure supplied and discharged to the tilting actuator, and a solenoid valve that generates an operating pressure for operating the regulator.

[0003] The variable displacement hydraulic rotary machine needs to be miniaturized (formed compactly) for mounting on a hydraulic excavator or the like. Therefore, there is a variable displacement hydraulic rotary machine having a configuration in which a regulator is attached to the upper side of the casing and a solenoid valve is attached to the upper side of this regulator (Patent Document 1).

[0004] In the variable displacement hydraulic rotary machine of this Patent Document 1, a solenoid valve is arranged on the upper side of the regulator, and the solenoid valve is arranged at the uppermost part of the variable displacement hydraulic rotary machine. Therefore, the air bleeding line provided for bleeding air in the variable displacement hydraulic rotary machine has a structure that passes from the casing through the regulator and the solenoid valve. Further, the air bleeding line is used to return the drain discharged from the solenoid valve to the hydraulic oil tank.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] Here, the solenoid valve generates the operating pressure applied to the regulator by adjusting the opening amount when discharging the source pressure from the pilot pump into the drain chamber. If the drain chamber and air vent line have a structure that is prone to pressure loss, the drain flow rate (pressure) discharged into the drain chamber will fluctuate in order to obtain the target operating pressure, making it impossible to obtain a stable operating pressure.

[0007] In contrast, Patent Document 1 has a long structure in which the air vent line passes from the casing through the regulator and solenoid valve, which makes it prone to pressure loss. As a result, the operating pressure in the structure of Patent Document 1 may be unstable, and the control of the variable capacity section may become unstable. Furthermore, if the air vent line is long, it is not only difficult to vent the air, which takes time, but if air remains, the control becomes unstable.

[0008] The present invention has been made in view of the problems of the prior art described above, and the object of the present invention is to provide a variable displacement hydraulic rotary machine that can stably control the variable displacement section by stabilizing the operating pressure through the smooth discharge of drain from the solenoid valve. [Means for solving the problem]

[0009] The present invention relates to a variable-capacity hydraulic rotary machine comprising: a casing for a hydraulic rotary machine having a variable-capacity section; a tilt actuator provided in the casing for tilting the variable-capacity section in accordance with tilt control pressure supplied and discharged from the outside; a regulator attached to the casing for variablely controlling the tilt control pressure supplied and discharged to the tilt actuator; and a solenoid valve for generating operating pressure to operate the regulator, wherein the solenoid valve comprises: a valve block attached to the regulator; a drain port provided in the valve block; a valve body displaceably provided within the valve block; and a solenoid actuator attached to the valve block for displacing the valve body, wherein the regulator is provided with a regulator drain chamber communicating with a casing drain chamber in the casing; an opening is provided on the side surface of the regulator leading to the regulator drain chamber; the valve block is provided with a projection that protrudes from a mounting surface attached to the side surface of the regulator and fits into the opening; and the drain port is provided on the projection so as to be exposed into the regulator drain chamber when the projection is fitted into the opening. [Effects of the Invention]

[0010] According to the present invention, a variable displacement hydraulic rotary machine can smoothly discharge drain from the solenoid valve, stabilize the operating pressure, and stably control the variable displacement section. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing a variable displacement axial piston pump according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the main part of Figure 1, with the cross-sectional position changed. [Modes for carrying out the invention]

[0012] Hereinafter, a variable displacement hydraulic rotary machine according to an embodiment of the present invention will be described in detail with reference to Figures 1 and 2, using a swashplate type variable displacement axial piston pump as an example.

[0013] In Figure 1, the swashplate type variable displacement axial piston pump 1 (hereinafter referred to as pump 1), which functions as a variable displacement hydraulic rotary machine, is composed of a casing 2, tilt actuator 18, regulator 20, and solenoid valve 22, which will be described later.

[0014] The casing 2 that constitutes the outer shell of the pump 1 is attached to a prime mover (not shown) such as an engine or electric motor. The casing 2 is composed of a front casing 3, a rear casing 4, and an actuator mounting section 5, which will be described later.

[0015] The front casing 3 is formed in a bottomed cylindrical shape by a base end 3A on the motor side and a cylindrical portion 3B extending from around the base end 3A toward the tip side opposite the motor. The base end 3A of the front casing 3 is attached to the motor. A casing drain chamber 6 is formed inside the front casing 3.

[0016] Furthermore, the rear casing 4 is attached to the front end of the front casing 3 (opposite the motor) so as to close off the front casing 3. The rear casing 4 has an intake pipe 4A, a discharge pipe 4B, etc. formed within it.

[0017] The actuator mounting portion 5 is located on the upper side of the cylindrical portion 3B of the front casing 3 when it is mounted to the prime mover (as shown in Figure 1). The actuator mounting portion 5 is positioned towards the tip of the cylindrical portion 3B, rather than in the axial direction (the extension direction of the rotation shaft 7, which will be described later) of the cylindrical portion 3B. The actuator mounting portion 5 is formed, for example, in a box shape, and the end face on the base end side, located in the axial direction of the cylindrical portion 3B, is a vertical regulator mounting surface 5A. This ensures that there is space between the regulator mounting surface 5A and the prime mover for arranging the regulator 20 and the solenoid valve 22.

[0018] As shown in Fig. 2, a communication port 5B that communicates with the uppermost part of a casing drain chamber 6 described later is open on a regulator mounting surface 5A. This communication port 5B communicates with a regulator drain chamber 21D of a regulator 20 described later. Further, since the communication port 5B communicates with the uppermost part of the casing drain chamber 6, air in the casing drain chamber 6 can be discharged to the regulator drain chamber 21D side.

[0019] The casing drain chamber 6 is provided inside the casing 2. A cylinder block 10, a piston 12, an inclined plate 15, etc. are arranged in the lower part of the casing drain chamber 6, and a tilting actuator 18, etc. are arranged at an upper position of the casing drain chamber 6. The casing drain chamber 6 stores the hydraulic oil that has overflowed from the cylinder 11, etc., and discharges the excess hydraulic oil from the communication port 5B of the actuator mounting portion 5.

[0020] The rotating shaft 7 is rotatably supported by a front casing 3 and a rear casing 4 via a front bearing 8 and a rear bearing 9. The base end side of the rotating shaft 7 is connected to the output shaft of the prime mover.

[0021] The cylinder block 10 is provided in the lower part of the casing drain chamber 6 inside the front casing 3. The cylinder block 10 has a plurality of cylinders 11 arranged side by side in the circumferential direction, and the rotating shaft 7 is spline-coupled to the center thereof. A piston 12 is slidably inserted into each cylinder 11 of the cylinder block 10. A valve plate 13 that slidably contacts the cylinder block 10 is arranged between the cylinder block 10 and the rear casing 4. Suction ports 13A and discharge ports 13B for communicating the cylinders 11 with a suction pipeline 4A and a discharge pipeline 4B formed in the rear casing 4 are formed in this valve plate 13.

[0022] A cradle 14 is fixed to the inner surface of the bottom 3A of the front casing 3 facing the end face on the prime mover side of the cylinder block 10. The cradle 14 slidably holds the swash plate 15 as a capacity variable part and guides the tilting of the swash plate 15, so that the swash plate 15 tilts while sliding with respect to the cradle 14. Between the swash plate 15 and the piston 12, a cam plate 16 and a shoe 17 are arranged. Thereby, the tilting of the swash plate 15 is transmitted to the piston 12 via the cam plate 16 and the shoe 17, and the movable range of the piston 12 in the cylinder 11, that is, the push-back volume, is determined.

[0023] The tilting actuator 18 is composed of a servo piston provided in the upper part of the casing drain chamber 6 in the front casing 3. The tilting actuator 18 tilts the swash plate 15 according to the tilting control pressure supplied and discharged from the outside. A servo plate 19 is fitted into a recess (not shown) of the tilting actuator 18. An arm 15A extending from the swash plate 15 is inserted into the servo plate 19. Thereby, the tilting actuator 18 can adjust the tilting angle of the swash plate 15 by transmitting its operation to the swash plate 15 via the arm 15A and the like.

[0024] The regulator 20 is attached to an actuator attachment portion 5 provided on the front casing 3 of the casing 2. The regulator 20 variably controls the tilting control pressure supplied and discharged to the tilting actuator 18. The regulator 20 includes a spool, a feedback link, etc. (none of which are shown) in a regulator casing 21 described later.

[0025] The regulator casing 21 is attached to the regulator attachment surface 5A of the actuator attachment portion 5. The regulator casing 21 is formed as a stepped block body. The regulator casing 21 has a contact surface 21A that contacts the regulator attachment surface 5A, a side surface 21B opposite to the regulator attachment surface 5A, and an upper end surface 21C at the uppermost part.

[0026] Furthermore, a regulator drain chamber 21D is provided inside the regulator casing 21, which opens to the contact surface 21A and communicates with the casing drain chamber 6 inside the casing 2. In addition, an opening 21E is provided on the side surface 21B of the regulator casing 21, which leads to the regulator drain chamber 21D. Moreover, a drain piping port 21F is provided on the upper part of the regulator casing 21, which is the upper part of the regulator 20, extending downward from the upper end surface 21C and communicating with the regulator drain chamber 21D.

[0027] The regulator drain chamber 21D is connected to the upper part of the casing drain chamber 6. The regulator drain chamber 21D has a large space on the casing drain chamber 6 side and a small space on the opposite side, the opening 21E side. The upper surface of the casing drain chamber 6 is provided with a curved (concave) ceiling surface 21D1, and the drain piping port 21F opens onto this upper surface. Therefore, the passage widens from the drain port 24 provided in the valve block 23 (described later) toward the drain piping port 21F. This reduces the resistance to the hydraulic fluid discharged from the drain port 24, allowing for quick and accurate control of the pilot pressure by the solenoid valve 22.

[0028] Furthermore, the ceiling surface 21D1 of the regulator drain chamber 21D is formed to be curved and rise from the drain port 24 towards the drain piping port 21F. As a result, the air flowing out from the drain port 24 can move smoothly towards the drain piping port 21F by following the ceiling surface 21D1.

[0029] The opening 21E is located below the drain piping port 21F, which will be described later, and is provided at the top of the regulator casing 21 of the regulator 20. The opening 21E is formed by a small-diameter portion 21E1 on the side 21B and a large-diameter portion 21E2 on the regulator drain chamber 21D side. The projection 23C of the valve block 23 is inserted into the small-diameter portion 21E1. The large-diameter portion 21E2 is located on the outer circumference of the drain port 24 of the valve block 23. This allows hydraulic fluid to be discharged from the drain port 24 to the regulator drain chamber 21D through the large-diameter portion 21E2.

[0030] The drain piping port 21F is connected to the hydraulic oil tank via piping (not shown). This allows the drain piping port 21F to return the drain (hydraulic oil) discharged into the casing drain chamber 6 and the regulator drain chamber 21D back to the hydraulic oil tank. The drain piping port 21F can also bleed (discharge) air along with the drain.

[0031] The solenoid valve 22 is attached to the regulator 20. The solenoid valve 22 generates the operating pressure necessary to operate the regulator 20. The solenoid valve 22 consists of a valve block 23, a drain port 24, a valve body 25, and an electromagnetic actuator 26, which will be described later.

[0032] The valve block 23 is attached to the regulator casing 21 of the regulator 20. The valve block 23 has a mounting surface 23A that is attached to the side surface 21B of the regulator casing 21, a mounting end surface 23B on the opposite side of the mounting surface 23A, and a projection 23C that protrudes from the mounting surface 23A and fits into the opening 21E. The valve block 23 also has a bottomed valve body housing hole 23D that extends parallel to the rotation axis 7, with one end opening to the mounting end surface 23B and the other end reaching the projection 23C. The valve body 25, which will be described later, is displaceably housed in this valve body housing hole 23D. Furthermore, the valve block 23 has a drain port 24, which will be described later, on the projection 23C.

[0033] The valve block 23 is attached to the regulator casing 21 by fitting its projection 23C into the small-diameter portion 21E1 of the opening 21E of the regulator casing 21, and with its mounting surface 23A in contact with the side surface 21B. Therefore, the projection 23C penetrates the small-diameter portion 21E1 and the large-diameter portion 21E2 to reach the regulator drain chamber 21D. As a result, the drain port 24 provided on the projection 23C, described later, can communicate with the regulator drain chamber 21D over a short distance through the gap with the large-diameter portion 21E2.

[0034] The drain port 24 is provided on the projection 23C of the valve block 23. As a result, the drain port 24 is exposed into the regulator drain chamber 21D with the projection 23C fitted into the opening 21E (opens into the regulator drain chamber 21D). Specifically, the drain port 24 extends radially from the projection 23C and communicates the valve body housing hole 23D with the outer circumferential surface of the projection 23C. In addition, part or all of the drain port 24 extends beyond the small diameter portion 21E1 of the opening 21E and opens into the large diameter portion 21E2. Furthermore, the drain port 24 is provided on the upper part of the projection 23C with an upward opening.

[0035] Therefore, the drain port 24 can smoothly discharge the drain from the valve body housing hole 23D into the regulator drain chamber 21D. Furthermore, the drain port 24, which opens upwards, can discharge any air contained in the drain into the regulator drain chamber 21D. This allows the drain port 24 to facilitate the flow of drain, enabling the solenoid valve 22 (valve body 25) to operate smoothly and accurately. It also allows for easy and reliable air bleeding.

[0036] The valve body 25 is displaceable within the valve block 23. The valve body 25 has a stepped cylindrical shape and is housed in the valve body housing hole 23D of the valve block 23. One end of the valve body 25 is connected to the operating part of the electromagnetic actuator 26.

[0037] The electromagnetic actuator 26 is attached to the mounting end face 23B of the valve block 23. The electromagnetic actuator 26 constitutes a power source that displaces the valve body 25 in the valve body housing hole 23D.

[0038] Here, the actuator mounting portion 5 of the casing 2, the regulator 20 (regulator casing 21), the valve block 23 of the solenoid valve 22, and the electromagnetic actuator 26 are arranged in series (stacked) in the axial direction of the rotating shaft 7.

[0039] The variable displacement axial piston pump 1 according to this embodiment has the configuration described above, and its operation will now be explained.

[0040] When the rotating shaft 7 is driven by the prime mover, the cylinder block 10 rotates together with the rotating shaft 7. Each piston 12 inserted into each cylinder 11 of the cylinder block 10 is provided with a shoe 17, and each shoe 17 slides on the swash plate 15. As a result, each piston 12 repeatedly performs an intake stroke in which it draws hydraulic fluid into the cylinder 11 as it slides from top dead center to bottom dead center, and a discharge stroke in which it discharges the hydraulic fluid from the cylinder 11 as pressurized oil as it slides from bottom dead center to top dead center.

[0041] To adjust the pump capacity (discharge volume of pressurized oil) of pump 1, the tilt actuator 18 is operated by the solenoid valve 22 to change the tilt angle of the swash plate 15. This increases or decreases the stroke amount of each piston 12, allowing for variable control of the pump capacity of pump 1.

[0042] Thus, according to this embodiment, the regulator casing 21 of the regulator 20 is provided with a regulator drain chamber 21D that communicates with the casing drain chamber 6 inside the regulator casing 21. Furthermore, the side surface 21B of the regulator casing 21 is provided with an opening 21E that leads to the regulator drain chamber 21D. In addition, the valve block 23 of the solenoid valve 22 is provided with a projection 23C that protrudes from a mounting surface 23A attached to the side surface 21B of the regulator casing 21 and fits into the opening 21E. On top of this, the drain port 24 is provided on the projection 23C so as to be exposed into the regulator drain chamber 21D when the projection 23C is fitted into the opening 21E.

[0043] Therefore, the drain port 24 of the solenoid valve 22 can communicate with the regulator drain chamber 21D over a short distance, allowing drain to be smoothly discharged into the regulator drain chamber 21D (while suppressing pressure loss). As a result, the operating pressure for operating the solenoid valve 22 and the regulator 20 can be stabilized, and the swash plate 15, which acts as a variable capacity unit, can be stably controlled. In addition, air bleeding of the solenoid valve 22 can be easily and properly performed (without leaving any air behind) through the drain port 24.

[0044] The opening 21E of the regulator casing 21 is located below the drain piping port 21F provided at the top of the regulator casing 21, and the regulator drain chamber 21D is formed such that the ceiling surface 21D1 rises from the drain port 24 towards the drain piping port 21F. As a result, the air flowing out from the drain port 24 can move smoothly towards the drain piping port 21F by following the ceiling surface 21D1, allowing the air to be removed quickly and completely, thereby improving the efficiency of the air bleeding operation.

[0045] The regulator drain chamber 21D is connected to the upper part of the casing drain chamber 6. The drain port 24 constitutes an air vent port. By using the drain port 24 as an air vent port, the air venting operation of the solenoid valve 22 can be performed quickly and accurately.

[0046] Furthermore, the drain port 24 is provided with an upward opening at the top of the projection 23C of the valve block 23. This allows the drain port 24 to quickly discharge air using the buoyancy of light air.

[0047] In the embodiments described, the example of application to a swashplate-type variable displacement axial piston pump 1 as a variable displacement hydraulic rotary machine was used. However, the present invention is not limited to this, and may be applied to, for example, a swashplate-type variable displacement axial piston motor, a slanted-shaft type variable displacement axial piston pump or motor, etc. [Explanation of Symbols]

[0048] 1. Variable displacement axial piston pump (variable displacement hydraulic rotary pump) 2 Casing 5 Actuator mounting section 6. Casing Drain Chamber 15. Swashplate (Variable Volume Section) 20 Regulators 21 Regulator Casing 21B Side 21C Top surface 21D Regulator Drain Chamber 21D1 Ceiling surface 21E opening 21F Drain piping port 22 Solenoid valve 23 Valve block 23A Mounting surface 23C Protrusion 24 Drain Ports 25 Valve body 26 Electromagnetic Actuator

Claims

1. A casing for a hydraulic rotary machine having a variable capacity section, A tilt actuator is provided in the casing and tilts the variable capacity section in accordance with the tilt control pressure supplied and discharged from the outside, A regulator attached to the casing variably controls the tilt control pressure supplied to and discharged from the tilt actuator, A solenoid valve that generates the operating pressure for operating the regulator, Equipped with, The solenoid valve is A valve block attached to the regulator, A drain port provided in the valve block, A valve body provided in a displaceable manner within the valve block, An electromagnetic actuator attached to the valve block for displacing the valve body, In a variable displacement hydraulic rotary machine equipped with, The regulator is provided with a regulator drain chamber that communicates with the casing drain chamber within the casing. An opening leading to the regulator drain chamber is provided on the side of the regulator. The valve block is provided with a projection that protrudes from the mounting surface attached to the side surface of the regulator and fits into the opening. The variable displacement hydraulic rotary machine is characterized in that the drain port is provided on the protrusion such that it is exposed into the regulator drain chamber when the protrusion is fitted into the opening.

2. In the variable displacement hydraulic rotary machine according to claim 1, The aforementioned opening is located below the drain piping port provided at the top of the regulator. The variable displacement hydraulic rotary machine is characterized in that the regulator drain chamber is formed such that the ceiling surface rises from the drain port toward the drain piping port.

3. In the variable displacement hydraulic rotary machine according to claim 1, A variable displacement hydraulic rotary machine characterized in that the regulator drain chamber is in communication with the upper part of the casing drain chamber.

4. In the variable displacement hydraulic rotary machine according to claim 1, The variable displacement hydraulic rotary machine is characterized in that the drain port is provided with an upward opening at the upper part of the protrusion.

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