Variable displacement hydraulic rotary machine

Abstract

To make it possible to shorten a first pilot pressure oil passage and a second pilot pressure oil passage, reduce pressure loss, and improve operation performance of a tilting actuator, a regulator, and a solenoid valve.SOLUTION: A variable displacement axial piston pump 1 comprises: a first pilot pressure oil passage 22 located on an upper side of a servo piston 18, provided in a casing 2, and connected to a solenoid valve 21 and a tilting actuator 16; and a second pilot pressure oil passage 25 located on the upper side of the servo piston 18, provided in the casing 2, and connected to the tilting actuator 16. The solenoid valve 21 is attached to a solenoid valve attachment surface 5B of an actuator attachment part 5 formed on an upper side of the casing 2 so as to sandwich the first pilot pressure oil passage 22 and the second pilot pressure oil passage 25 between itself and the servo piston 18 of the tilting actuator 16.SELECTED DRAWING: Figure 1

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 used as a variable displacement hydraulic pump or a variable displacement hydraulic motor. Background Art

[0002] Generally, construction machines such as hydraulic excavators are 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 variable displacement hydraulic motor constitute a variable displacement hydraulic rotary machine.

[0003] The variable displacement hydraulic rotary machine includes, for example, a casing having a drain chamber inside, a rotary shaft rotatably provided in the casing, a cylinder block provided around the rotary shaft and having a plurality of cylinders spaced apart in a circumferential direction and extending in an axial direction, a plurality of pistons reciprocably inserted into the plurality of cylinders of the cylinder block, a displacement variable portion that increases or decreases the reciprocating stroke of the plurality of pistons by being tilted with respect to the rotary shaft, a tilting actuator provided in the casing that tilts the displacement variable portion when a servo piston is moved, a regulator provided in the casing that moves the servo piston, and a solenoid valve that generates pilot pressure for operating the regulator. Further, in the casing, a first pilot pressure oil passage and a second pilot pressure oil passage connected to the tilting actuator are provided at a position above the servo piston.

[0004] Here, a plurality of oil passages are connected to the tilting actuator, the regulator, and the solenoid valve, for example, a pilot pressure oil passage serving as a primary pressure oil passage, an adjusted secondary pressure oil passage, and a drain pressure oil passage. For this reason, there is a variable displacement hydraulic rotary machine configured such that the solenoid valve is attached to the regulator in consideration of the routing of each oil passage (Patent Document 1). Prior Art Documents Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-211682 [Overview of the project] [Problems that the invention aims to solve]

[0006] Here, Patent Document 1 describes a configuration in which a regulator is attached to the casing (tilting actuator), and a solenoid valve is attached to the regulator. For this reason, the first pilot pressure oil passage and the second pilot pressure oil passage are provided across the tilting actuator, regulator, and solenoid valve, even though they do not need to be connected to the regulator. Consequently, the first pilot pressure oil passage and the second pilot pressure oil passage become unnecessarily long, increasing pressure loss, which leads to a problem of reduced operability when operating the tilting actuator, regulator, and solenoid valve.

[0007] 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 improve the operability of the tilt actuator, regulator and solenoid valve by shortening the first pilot pressure oil passage and the second pilot pressure oil passage, thereby suppressing pressure loss. [Means for solving the problem]

[0008] The present invention comprises a casing having a drain chamber inside, a rotating shaft rotatably provided within the casing, a cylinder block having a plurality of cylinders provided around the rotating shaft within the casing and spaced apart in the circumferential direction and extending in the axial direction, a plurality of pistons reciprocally fitted into the plurality of cylinders of the cylinder block, a variable capacity unit that increases or decreases the reciprocating stroke of the plurality of pistons by being tilted with respect to the rotating shaft within the casing, a tilt actuator provided in the casing that tilts the variable capacity unit by the movement of a servo piston, and the casing provided, A variable displacement hydraulic rotary machine comprising a regulator for moving a servo piston and a solenoid valve for generating pilot pressure to operate the regulator, further comprising: a first pilot pressure oil passage located above the servo piston and provided in the casing, connected to the solenoid valve and the tilt actuator; and a second pilot pressure oil passage located above the servo piston and provided in the casing, connected to the tilt actuator, wherein the solenoid valve is mounted on a solenoid valve mounting surface formed on the upper side of the casing so as to sandwich the first pilot pressure oil passage and the second pilot pressure oil passage between itself and the servo piston. The casing is provided with a casing drain pressure oil passage that communicates with the drain chamber, the solenoid valve is provided with a solenoid valve drain pressure oil passage, and the solenoid valve drain pressure oil passage communicates with the drain chamber through the casing drain pressure oil passage. It is. [Effects of the Invention]

[0009] According to the present invention, the variable displacement hydraulic rotary machine can shorten the first pilot pressure oil passage and the second pilot pressure oil passage, thereby suppressing pressure loss and improving the operability of the tilt actuator, regulator, and solenoid valve. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of a variable displacement axial piston pump according to an embodiment of the present invention, taken from the direction indicated by arrow II in Figure 2. [Figure 2] This is a cross-sectional view of a variable displacement axial piston pump taken from the direction indicated by arrow II-II in Figure 1. [Figure 3] This is a hydraulic circuit diagram for tilting the swashplate. [Modes for carrying out the invention]

[0011] 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 to 3, using a swashplate type variable displacement axial piston pump as an example.

[0012] In Figures 1 and 2, 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 the following components: casing 2, rotating shaft 7, cylinder block 8, piston 10, swashplate 13, tilt actuator 16, regulator 20, solenoid valve 21, first pilot pressure oil passage 22, second pilot pressure oil passage 25, casing drain pressure oil passage 26, and solenoid valve drain pressure oil passage 27.

[0013] 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.

[0014] 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, described later, is formed inside the front casing 3.

[0015] 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.

[0016] 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 from the middle to the tip of the cylindrical portion 3B in the axial direction (the longitudinal direction of the rotation axis 7, which will be described later). The actuator mounting portion 5 is formed, for example, in a box shape, and its interior is the tilt control cylinder (a cylindrical surface which is part of the inner surface of the casing 2) 17 of the tilt actuator 16, which will be described later.

[0017] Furthermore, the actuator mounting portion 5 has a base end face (part of the outer surface of the casing 2) located in the axial middle of the cylindrical portion 3B, which serves as the regulator mounting surface 5A, and an upper end face (part of the outer surface of the casing 2) which serves as the solenoid valve mounting surface 5B. The regulator 20, described later, is mounted on the regulator mounting surface 5A, and the solenoid valve 21, described later, is mounted on the solenoid valve mounting surface 5B.

[0018] As described above, the actuator mounting section 5 is equipped with a tilt actuator 16, a regulator 20, a solenoid valve 21, and the like. Therefore, a first pilot pressure oil passage 22, a second pilot pressure oil passage 25, and a casing drain pressure oil passage 26, described later, are provided to hydraulically connect these tilt actuators 16, regulator 20, solenoid valve 21, and the like.

[0019] The casing drain chamber 6, which serves as a drain chamber, is located inside the casing 2. The cylinder block 8, piston 10, swash plate 13, etc., are arranged in the lower part of the casing drain chamber 6. The upper part of the casing drain chamber 6 extends to the actuator mounting section 5 and is connected to the tilt control cylinder 17. The casing drain chamber 6 stores the hydraulic fluid that overflows from the cylinder 9, etc., and discharges the excess hydraulic fluid as drain oil through the casing drain pressure oil passage 26 and the solenoid valve drain pressure oil passage 27.

[0020] As shown in Figure 2, the rotating shaft 7 extends in the axial direction of the cylindrical portion 3B of the front casing 3, and is rotatably supported within the casing 2, specifically by the front casing 3 and the rear casing 4. The proximal end side of the rotating shaft 7 is connected to an output shaft (not shown) of a prime mover.

[0021] The cylinder block 8 is provided in the lower portion of the casing drain chamber 6 inside the front casing 3. The cylinder block 8 has a plurality of cylinders 9 arranged side by side in the circumferential direction, and the rotating shaft 7 is spline-coupled to the center of the cylinder block 8. A piston 10 is slidably fitted into each of the plurality of cylinders 9 of the cylinder block 8. A valve plate 18 in sliding contact with the cylinder block 8 is disposed between the cylinder block 8 and the rear casing 4. The valve plate 11 is formed with a suction port 11A and a discharge port 11B for communicating the cylinder 9 with a suction pipe 4A and a discharge pipe 4B formed in the rear casing 4.

[0022] A cradle 12 is fixed to the inner surface of the bottom portion 3A of the front casing 3 facing the end surface of the cylinder block 8 on the prime mover side. The cradle 12 slidably holds a swash plate 13 serving as a variable capacity portion inside the casing 2 and guides the tilting of the swash plate 13, thereby tilting the swash plate 13 while sliding relative to the cradle 12. A cam plate 14 and a shoe 15 are disposed between the swash plate 13 and the piston 10. Accordingly, the tilting movement of the swash plate 13 is transmitted to the piston 10 via the cam plate 14 and the shoe 15, so that the reciprocating stroke of the piston 10 within the cylinder 9, that is, the displacement volume, is determined.

[0023] Further, a tilt angle sensor (not shown) for detecting the angle when the swash plate 13 is tilted is provided. The angle of the swash plate 13 detected by the tilt angle sensor is used together with the displacement volume and the rotation speed of the rotating shaft 7 to calculate the discharge flow rate of the pump.

[0024] The tilt actuator 16 is located within the actuator mounting portion 5 of the casing 2. The tilt actuator 16 tilts the swash plate 13 in response to the tilt control pressure supplied and discharged from the outside. The tilt actuator 16 includes a tilt control cylinder 17 formed in the actuator mounting portion 5 and a servo piston 18 provided within the tilt control cylinder 17.

[0025] The tilt control cylinder 17 is formed as a circular hole extending left and right perpendicular to the axial direction of the cylindrical portion 3B of the front casing 3. Furthermore, as shown in Figure 2, the tilt control cylinder 17 has a small diameter hole portion 17A at one end in the longitudinal direction and a large diameter hole portion 17B at the other end in the longitudinal direction. The tilt control cylinder 17 is connected to the upper part of the casing drain chamber 6.

[0026] The servo piston 18 is slidably inserted into the tilt control cylinder 17. The servo piston 18 is formed as a stepped cylindrical body by a small-diameter portion 18A inserted into a small-diameter hole 17A of the tilt control cylinder 17 and a large-diameter portion 18B inserted into a large-diameter hole 17B. The servo piston 18 forms a small-diameter oil chamber 19A between the small-diameter portion 18A and the small-diameter hole 17A, and a large-diameter oil chamber 19B between the large-diameter portion 18B and the large-diameter hole 17B. In addition, an engagement groove 18C is provided in the middle of the servo piston 18 in the longitudinal direction. The tip of the arm 13A of the swash plate 13 engages with this engagement groove 18C.

[0027] The tilt actuator 16 then supplies and discharges tilt control pressure from the regulator 20 and solenoid valve 21 (described later) to the small-diameter oil chamber 19A, the large-diameter oil chamber 19B, etc., causing the servo piston 18 to slide and displace within the tilt control cylinder 17. This displacement of the servo piston 18 is transmitted to the swash plate 13 via the arm 13A, allowing the tilt actuator 16 to adjust the tilt angle of the swash plate 13.

[0028] As shown in Figure 1, the regulator 20 is mounted on the regulator mounting surface 5A of the actuator mounting portion 5 provided on the front casing 3 of the casing 2. The regulator 20 variably controls the tilt control pressure supplied to and discharged from the small-diameter oil chamber 19A and the large-diameter oil chamber 19B of the tilt actuator 16. As shown in Figures 1 and 3, the regulator 20 includes a regulator casing 20A, a spool valve 20B, a feedback link 20C, etc. The regulator 20 provides feedback control of the tilt actuator 16 via the feedback link 20C by displacing the spool valve 20B in accordance with the tilting operation of the swash plate 13.

[0029] The solenoid valve 21 is located on the upper side of the casing 2. Specifically, the solenoid valve 21 is mounted on the solenoid valve mounting surface 5B of the actuator mounting portion 5. The solenoid valve 21 generates pilot pressure (operating pressure) to operate the tilt actuator 16 and the regulator 20. The solenoid valve 21 consists of a valve block 21A, a valve body 21B, and an electromagnetic actuator 21C. The valve block 21A of the solenoid valve 21 is also provided with a solenoid valve pilot pressure oil passage 24, a solenoid valve drain pressure oil passage 27, etc., which will be described later.

[0030] The valve block 21A is formed as a rectangular parallelepiped block and is attached to the solenoid valve mounting surface 5B of the actuator mounting portion 5. The valve block 21A has a valve body housing hole (not shown) that extends parallel to the rotation axis 7. The valve body 21B is displaceably housed in this valve body housing hole.

[0031] The electromagnetic actuator 21C is attached to the front end surface (the end surface on the rear casing 4 side) of the valve block 21A. The electromagnetic actuator 21C constitutes a power source that displaces the valve body 21B in the valve body housing hole.

[0032] Here, the solenoid valve 21 is mounted on the solenoid valve mounting surface 5B formed on the upper side of the casing 2 so as to sandwich the first pilot pressure oil passage 22 and the second pilot pressure oil passage 25, which will be described later, between it and the servo piston 18 of the tilt actuator 16. Therefore, by mounting the solenoid valve 21 to the actuator mounting portion 5 which forms the outer shell of the tilt actuator 16, the solenoid valve 21 and the tilt actuator 16 can be placed in close proximity to each other without the regulator 20 being in between.

[0033] The first pilot pressure oil passage 22 is located above the servo piston 18 of the tilt actuator 16 and is provided in the actuator mounting portion 5 of the casing 2. As shown in Figure 2, the first pilot pressure oil passage 22 extends in the left-right direction along the servo piston 18. One end of the first pilot pressure oil passage 22 is connected to the small-diameter oil chamber 19A of the tilt actuator 16. The middle portion of the first pilot pressure oil passage 22 in the longitudinal direction is connected to the solenoid valve pilot pressure oil passage 24, which will be described later, provided in the solenoid valve 21 via the casing pilot pressure oil passage 23 provided in the casing 2 (actuator mounting portion 5). The casing pilot pressure oil passage 23 and the solenoid valve pilot pressure oil passage 24 extend linearly upward from the first pilot pressure oil passage 22.

[0034] The second pilot pressure oil passage 25 is located above the servo piston 18 and is provided in the actuator mounting section 5, aligned with the first pilot pressure oil passage 22. The second pilot pressure oil passage 25 is connected to the large-diameter oil chamber 19B of the tilt actuator 16.

[0035] Here, the length of the first pilot pressure oil passage 22 and the second pilot pressure oil passage 25 can be shortened by positioning the solenoid valve 21 close to the tilt actuator 16. In other words, shorter oil passages can reduce (minimize) the pressure loss when the hydraulic fluid is circulated. Furthermore, the pressure loss when the hydraulic fluid is circulated can also be reduced by arranging the casing pilot pressure oil passage 23 and the solenoid valve pilot pressure oil passage 24 in a straight line.

[0036] As shown in Figure 1, the casing drain pressure oil passage 26 is provided in the casing 2 (actuator mounting portion 5). The casing drain pressure oil passage 26 extends linearly in the vertical direction, with its lower end communicating with the tilt control cylinder 17 (casing drain chamber 6) and its upper end opening to the solenoid valve mounting surface 5B.

[0037] Furthermore, the solenoid valve drain pressure oil passage 27 is provided in the valve block 21A of the solenoid valve 21. The solenoid valve drain pressure oil passage 27 extends linearly in the vertical direction, and its lower side is in communication with the casing drain pressure oil passage 26. The upper part of the solenoid valve drain pressure oil passage 27 opens onto the upper surface of the valve block 21A and is normally closed by the drain plug 28. As a result, the solenoid valve drain pressure oil passage 27 is in communication with the casing drain chamber 6 through the casing drain pressure oil passage 26.

[0038] Furthermore, by positioning the solenoid valve 21 close to the tilt actuator 16, the length of the casing drain pressure oil passage 26 and the solenoid valve drain pressure oil passage 27 can be shortened. This makes it possible to suppress (reduce) the pressure loss when circulating the drain oil.

[0039] Furthermore, the casing drain pressure oil passage 26 and the solenoid valve drain pressure oil passage 27 extend in a straight line vertically from the casing drain chamber 6 to the top of the valve block 21A of the solenoid valve 21. Therefore, the oil passages of the casing drain pressure oil passage 26 and the solenoid valve drain pressure oil passage 27 can be shortened, and resistance when drain oil and air flow can be reduced.

[0040] The variable displacement axial piston pump 1 according to this embodiment has the configuration described above, and its operation will now be explained.

[0041] When the rotating shaft 7 is rotated by the prime mover, the cylinder block 8 rotates together with the rotating shaft 7. Each piston 10 inserted into each cylinder 9 of the cylinder block 8 is provided with a shoe 15, and each shoe 15 slides on the swash plate 13. As a result, each piston 10 repeatedly performs an intake stroke in which it draws hydraulic fluid into the cylinder 9 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 9 as pressurized oil as it slides from bottom dead center to top dead center.

[0042] To adjust the pump capacity (discharge volume of pressurized oil) of pump 1, the tilt actuator 16 is operated by the solenoid valve 21 to change the tilt angle of the swash plate 13. This increases or decreases the stroke amount of each piston 10, allowing for variable control of the pump capacity of pump 1.

[0043] Thus, according to this embodiment, the variable displacement axial piston pump 1 includes a first pilot pressure oil passage 22 located above the servo piston 18 and provided in the casing 2, connected to the solenoid valve 21 and the tilt actuator 16, and a second pilot pressure oil passage 25 located above the servo piston 18 and provided in the casing 2, connected to the tilt actuator 16. Furthermore, the solenoid valve 21, which generates pilot pressure for operating the regulator 20, is mounted on the solenoid valve mounting surface 5B of the actuator mounting portion 5 formed on the upper side of the casing 2, so as to sandwich the first pilot pressure oil passage 22 and the second pilot pressure oil passage 25 between the servo piston 18 of the tilt actuator 16 and the solenoid valve 21.Therefore, by positioning the solenoid valve 21 close to the tilt actuator 16, the length of the oil passages of the first pilot pressure oil passage 22 and the second pilot pressure oil passage 25 can be shortened.

[0044] This allows the short oil passage to reduce pressure loss when circulating the hydraulic fluid. As a result, the operability of the tilt actuator 16, regulator 20, and solenoid valve 21 can be improved.

[0045] Furthermore, the casing 2 is provided with a casing drain pressure oil passage 26 that communicates with the casing drain chamber 6, and the solenoid valve 21 is provided with a solenoid valve drain pressure oil passage 27. On top of this, the solenoid valve drain pressure oil passage 27 communicates with the casing drain chamber 6 through the casing drain pressure oil passage 26. As a result, the length of the oil passages 26 and the solenoid valve drain pressure oil passage 27 can be shortened because the tilt actuator 16 and the solenoid valve 21 are close together.

[0046] Furthermore, the casing drain pressure oil passage 26 and the solenoid valve drain pressure oil passage 27 extend in a straight line vertically from the casing drain chamber 6 to the top of the solenoid valve 21. This reduces pressure loss when oil flows through the casing drain pressure oil passage 26 and the solenoid valve drain pressure oil passage 27, allowing for efficient discharge of drain oil and 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 5B Solenoid valve mounting surface 6. Casing drain chamber (drain chamber) 7 Rotation axis 8 Cylinder Block 9 cylinders 10 pistons 13. Swashplate (Variable Volume Section) 16. Tilt Actuator 18 Servo Pistons 20 Regulators 21 Solenoid valve 22 First pilot pressure oil passage 25. Second pilot pressure oil passage 26 Casing drain pressure oil passage 27 Solenoid valve drain pressure oil passage

Claims

1. A casing with a drain chamber inside, A rotating shaft rotatably provided within the casing, A cylinder block having a plurality of cylinders provided around the rotating shaft within the casing, spaced apart in the circumferential direction and extending in the axial direction, A plurality of pistons are reciprocably inserted into the plurality of cylinders of the cylinder block, A variable capacity unit that increases or decreases the reciprocating stroke of the plurality of pistons by being tilted with respect to the rotating shaft within the casing, A tilt actuator is provided in the casing, and the variable capacity section is tilted by the movement of a servo piston, A regulator provided in the casing for moving the servo piston, A variable displacement hydraulic rotary machine comprising a solenoid valve that generates a pilot pressure for operating the regulator, A first pilot pressure oil passage is provided in the casing, located above the servo piston, and connected to the solenoid valve and the tilt actuator, A second pilot pressure oil passage is provided in the casing, located above the servo piston, and connected to the tilt actuator, Equipped with, The solenoid valve is mounted on a solenoid valve mounting surface formed on the upper side of the casing such that it sandwiches the first pilot pressure oil passage and the second pilot pressure oil passage between itself and the servo piston. The casing is provided with a casing drain pressure oil passage that communicates with the drain chamber. The solenoid valve is provided with a solenoid valve drain pressure oil passage. A variable displacement hydraulic rotary machine characterized in that the solenoid valve drain pressure oil passage is connected to the drain chamber through the casing drain pressure oil passage.

2. In the variable displacement hydraulic rotary machine according to claim 1, A variable displacement hydraulic rotary machine characterized in that the casing drain pressure oil passage and the solenoid valve drain pressure oil passage extend in a straight line vertically from the drain chamber to the top of the solenoid valve.

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