阅读说明：本技术 可变容量型液压泵和建筑机械 (Variable displacement hydraulic pump and construction machine ) 是由 赤见俊也 山口祥 于 2020-03-24 设计创作，主要内容包括：本发明提供一种可变容量型液压泵和建筑机械。本发明的可变容量型液压泵具备：壳体；多个柱塞,其设置于所述壳体内,绕第1旋转轴线公转；斜板,其设置于所述壳体内,以与所述第1旋转轴线交叉的第2旋转轴线为中心自转,并且,限制所述多个柱塞的沿着所述第1旋转轴线的方向上的移动；斜板旋转角输出部,其输出所述斜板的旋转角；以及传感器,其检测所述斜板旋转角输出部的位置。(The invention provides a variable displacement hydraulic pump and a construction machine. The variable displacement hydraulic pump of the present invention includes: a housing; a plurality of plungers disposed in the housing and revolving about a 1 st rotation axis; a swash plate that is provided in the housing, rotates about a 2 nd rotation axis intersecting the 1 st rotation axis, and regulates movement of the plurality of plungers in a direction along the 1 st rotation axis; a swash plate rotation angle output unit that outputs a rotation angle of the swash plate; and a sensor that detects a position of the swash plate rotation angle output portion.)

1. A variable displacement hydraulic pump is provided with:

a housing;

a plurality of plungers disposed in the housing and revolving about a 1 st rotation axis;

a swash plate that is provided in the housing, rotates about a 2 nd rotation axis intersecting the 1 st rotation axis, and regulates movement of the plurality of plungers in a direction along the 1 st rotation axis;

a swash plate rotation angle output unit that outputs a rotation angle of the swash plate; and

And a sensor that detects a position of the swash plate rotation angle output part.

2. The variable capacity hydraulic pump according to claim 1,

the rotation angle of the swash plate is controlled according to the output of the sensor.

3. The variable capacity hydraulic pump according to claim 1,

the sensor is a rotation angle sensor which is,

the rotation angle sensor is disposed on the 2 nd rotation axis.

4. The variable displacement hydraulic pump according to any one of claims 1 to 3,

the sensor is a potentiometer on which the sensor is mounted,

the swash plate rotation angle output unit is a connecting member having one end connected to the rotation detection shaft of the potentiometer in a non-rotatable manner and the other end connected to the swash plate in a rotatable manner.

5. The variable capacity hydraulic pump according to claim 4,

a protrusion is provided on either one of the connection member and the swash plate,

a recess for accommodating the protrusion is provided in any other one of the connecting member and the swash plate.

6. The variable capacity hydraulic pump according to claim 1,

the shell is provided with an opening part,

the sensor blocks the opening.

7. The variable capacity hydraulic pump according to claim 6,

the opening is formed on the 2 nd rotation axis.

8. A construction machine is provided with:

the variable displacement hydraulic pump according to any one of claims 1 to 7;

and a vehicle body on which the variable displacement hydraulic pump is mounted.

Technical Field

The present invention relates to a variable displacement hydraulic pump and a construction machine.

Background

As the variable displacement hydraulic pump, there is a swash plate type variable displacement hydraulic pump (hereinafter, simply referred to as a hydraulic pump) for supplying hydraulic oil to various hydraulic actuators mounted on a construction machine such as a hydraulic excavator. This hydraulic pump has a rotary shaft rotatably supported in a housing, and a cylinder that rotates integrally with the rotary shaft. The cylinder block is provided with a plurality of cylinder bores. A plunger is inserted into each cylinder hole. The cylinder bore and the plunger constitute a cylinder chamber.

Further, a swash plate supported so that the inclination angle thereof can be changed with respect to the housing is provided on the opposite side end of the plunger on the side where the cylinder chamber is formed. The rotation axis of the inclination angle of the swash plate is orthogonal to the rotation axis of the cylinder block. The plungers slide along the swash plate, and movement of the plungers within the cylinder bores is restricted by the swash plate. A regulator that changes the inclination angle of the swash plate is often connected to the swash plate via a rod. The inclination angle of the swash plate is adjusted by an adjuster, and the inclination angle of the swash plate is accurately controlled by feeding back the inclination angle via a lever.

With this configuration, when the plunger slides along the swash plate, the plunger slides in the cylinder hole. The change in the volume of the cylinder chamber caused by this is used to discharge the working oil at a predetermined flow rate. That is, the discharge amount of the hydraulic pump changes based on the inclination angle of the swash plate.

Various techniques are disclosed for accurately controlling the discharge rate of the hydraulic pump without deviation by detecting the inclination angle of the swash plate. For example, there are the following techniques: a swing angle of a lever for connecting the swash plate and the regulator is detected, and the inclination angle of the swash plate is calculated based on the detection result.

Disclosure of Invention

Problems to be solved by the invention

However, in a small construction machine, miniaturization of the hydraulic pump is desired. In such a hydraulic pump, the structure of the regulator may be simplified without providing a lever. In such a case, it is difficult to detect the inclination angle of the swash plate. For example, if the inclination angle of the swash plate is directly detected, a large-scale device such as a stroke sensor is required to improve the detection accuracy, or the manufacturing cost of the hydraulic pump may increase. Further, the position of a sensor for detecting the inclination angle of the swash plate is restricted, and the hydraulic pump may be increased in size.

The invention provides a variable displacement hydraulic pump and a construction machine, which can detect the inclination angle of a swash plate with simple structure and high precision and can be miniaturized.

Means for solving the problems

A variable displacement hydraulic pump according to an aspect of the present invention includes: a housing; a plurality of plungers disposed in the housing and revolving about a 1 st rotation axis; a swash plate that is provided in the housing, rotates about a 2 nd rotation axis intersecting the 1 st rotation axis, and regulates movement of the plurality of plungers in a direction along the 1 st rotation axis; a swash plate rotation angle output unit that outputs a rotation angle of the swash plate; and a sensor that detects a position of the swash plate rotation angle output portion.

With this configuration, the inclination angle of the swash plate is not directly detected by the sensor, but the movement of the swash plate rotation angle output unit may be detected by the sensor. Therefore, the manufacturing cost of the variable displacement hydraulic pump can be suppressed with a simple structure without a large-scale sensor.

Further, the layout of the sensor can be improved by merely changing the shape of the swash plate rotation angle output unit.

Therefore, the variable displacement hydraulic pump can be downsized.

In the above configuration, the rotation angle of the swash plate may be controlled based on an output of the sensor.

With this configuration, the swash plate can be moved with high accuracy.

In the above configuration, the sensor may be a rotation angle sensor, and the rotation angle sensor may be disposed on the 2 nd rotation axis.

With this configuration, the cost of the sensor can be reduced. Further, by disposing the rotation angle sensor on the 2 nd rotation axis, the inclination angle of the swash plate can be detected on the 2 nd rotation axis.

Therefore, the inclination angle of the swash plate can be detected more accurately.

In the above configuration, the sensor may be a potentiometer, and the swash plate rotation angle output unit may be a connecting member having one end connected to a rotation detection shaft of the potentiometer so as to be non-rotatable and the other end connected to the swash plate so as to be rotatable.

With this configuration, the variable displacement hydraulic pump can have a further simple structure.

In the above configuration, a protrusion may be provided on one of the connecting member and the swash plate, and a recess for receiving the protrusion may be provided on the other of the connecting member and the swash plate.

With this configuration, the connecting member and the swash plate can be easily connected to each other.

In the above configuration, the case may include an opening, and the sensor may close the opening.

With this configuration, the sensor can be easily attached to the housing.

In the above configuration, the opening may be formed on the 2 nd rotation axis.

With this configuration, the sensor can be easily attached to the 2 nd rotation axis. Therefore, the inclination angle of the swash plate can be detected with high accuracy while facilitating the installation of the sensor.

A construction machine according to another aspect of the present invention includes: the above-described variable displacement hydraulic pump; and a vehicle body on which the variable displacement hydraulic pump is mounted.

With this configuration, it is possible to provide a small construction machine capable of accurately detecting the inclination angle of the swash plate with a simple structure.

ADVANTAGEOUS EFFECTS OF INVENTION

The variable displacement hydraulic pump and the construction machine can detect the inclination angle of the swash plate with good accuracy by a simple structure, and can be reduced in size.

Drawings

Fig. 1 is a schematic configuration diagram of a construction machine according to an embodiment of the present invention.

Fig. 2 is a sectional view of a hydraulic pump in an embodiment of the present invention along an axial direction.

Fig. 3 is a perspective view of a part of a hydraulic pump in an embodiment of the present invention in an enlarged manner.

Fig. 4 is a perspective view of the swash plate according to the embodiment of the present invention, as viewed from the cylinder block side.

Fig. 5 is a perspective view of the swash plate according to the embodiment of the present invention, as viewed from the front flange side.

Fig. 6 is a perspective view showing a state where the rotation angle sensor is removed from the housing main body in the embodiment of the present invention.

Fig. 7 is a perspective view of the rotation angle sensor of fig. 3 and a part of the periphery of the rotation angle sensor.

Fig. 8 is an explanatory diagram illustrating a procedure of a method of attaching the rotation angle sensor in the embodiment of the present invention.

Fig. 9 is an explanatory diagram illustrating a procedure of a method of attaching the rotation angle sensor in the embodiment of the present invention.

Fig. 10 is an explanatory diagram illustrating a procedure of a method of attaching the rotation angle sensor in the embodiment of the present invention.

Description of the reference numerals

1. A hydraulic pump (variable displacement hydraulic pump); 2. a housing; 5. a sloping plate; 8. a rotation angle sensor (sensor); 9. a case main body (case); 10. a front flange (housing); 12a, a sensor mounting opening (opening); 21. a plunger; 36. a connecting pin (protrusion); 61. 1 st rotation detection shaft (rotation detection shaft); 63. a base part; 68. a connecting member (swash plate rotation angle output portion); 71. a connecting groove (concave portion); 77. a 2 nd rotation detection shaft (rotation detection shaft); 100. a construction machine; 101. a revolving body (vehicle body); 102. a traveling body (vehicle body); c1, center axis (1 st axis of rotation); c2, axis of rotation (2 nd axis of rotation).

Detailed Description

Next, embodiments of the present invention will be described with reference to the drawings.

(construction machine)

Fig. 1 is a schematic configuration diagram of a construction machine 100.

As shown in fig. 1, the construction machine 100 is, for example, a hydraulic excavator. The construction machine 100 includes a revolving structure (corresponding to the vehicle body of the claims) 101 and a traveling structure (corresponding to the vehicle body of the claims) 102. Revolving unit 101 is provided on traveling unit 102 so as to be able to revolve. The revolving unit 101 is provided with a hydraulic pump 1.

Rotator 101 includes: a cab 103 on which an operator can ride; a boom 104 having one end connected to the cab 103 so as to be swingable; an arm 105 having one end connected to the other end (distal end) of the boom 104 on the side opposite to the cab 103 so as to be swingable; and a bucket 106 connected to the other end (tip end) of arm 105 on the side opposite to boom 104 so as to be swingable. Further, a hydraulic pump 1 is provided in the cab 103. The cab 103, the boom 104, the arm 105, and the bucket 106 are driven by the hydraulic oil supplied from the hydraulic pump 1.

(Hydraulic pump)

Fig. 2 is a sectional view of the hydraulic pump 1. Fig. 3 is an enlarged perspective view of a part of the hydraulic pump 1.

As shown in fig. 2 and 3, the hydraulic pump 1 is a so-called swash plate type variable displacement hydraulic pump. The hydraulic pump 1 includes: a housing 2; a rotating shaft 3 supported to be rotatable with respect to the housing 2; a cylinder 4 housed in the housing 2 and fixed to the rotary shaft 3; a swash plate 5 rotatably housed in the casing 2 and controlling a discharge amount of the hydraulic oil discharged from the hydraulic pump 1; a 1 st urging portion 6 and a 2 nd urging portion 7 that control a rotation angle of the swash plate 5; and a rotation angle sensor 8 that detects the rotation angle of the swash plate 5.

In fig. 2, the scale of each member is appropriately changed to facilitate understanding of the description.

In fig. 3, the illustration of the housing 2 is simplified. In the following description, a direction parallel to the center axis (corresponding to the 1 st rotation axis of the claims) C1 of the rotary shaft 3 is simply referred to as an axial direction, a rotation direction of the rotary shaft 3 is simply referred to as a circumferential direction, and a radial direction of the rotary shaft 3 is simply referred to as a radial direction.

The housing 2 includes: a housing main body 9 having an opening 9 a; and a front flange 10 for closing the opening 9a of the housing main body 9. A bearing 11 for rotatably supporting one end of the rotary shaft 3 is provided on the bottom portion 9b of the casing main body 9 on the side opposite to the opening 9 a.

A guide recess 12 for attaching the rotation angle sensor 8 is formed in the side surface 9c of the housing main body 9 at a position corresponding to the swash plate 5. The rotation angle sensor 8 is attached to a predetermined position by the guide recess 12.

A sensor mounting opening (corresponding to an opening in claims) 12a for detecting a rotation angle is formed in the guide recess 12. The rotation angle sensor 8 is provided so as to close the sensor mounting opening 12 a. Further, detailed shapes and positions of the guide recess 12 and the sensor mounting opening portion 12a are discussed later.

In addition, on the side surface 9c of the housing main body 9, a 1 st guide portion 49 that guides a force application lever 46, which will be discussed later, of the 2 nd force application portion 7 is provided on the inner surface side. A mounting recess 48 communicating with the 1 st guide portion 49 is formed in the bottom portion 9b of the housing main body 9. A force application pin unit 50, which will be discussed later, of the 2 nd force application portion 7 is attached to the attachment recess 48.

A supply port and a discharge port, not shown, are formed in the housing main body 9. The supply port is connected to a tank not shown. The discharge port is connected to the cab 103, the boom 104, the arm 105, and the bucket 106 via a control valve or the like, not shown.

A swash plate support portion 30 is formed on the front flange 10 so as to protrude from an inner surface 10a on the housing main body 9 side. The swash plate support portion 30 rotatably supports the swash plate 5. The swash plate support portion 30 is formed with a recess 30a having a semicircular shape when viewed in the radial direction. The swash plate 5 abuts on the recess 30 a.

Further, a male screw-shaped stopper 40 is provided on the front flange 10 on the radially outer side. A part of the swash plate 5 abuts against a stopper 40, and the stopper 40 regulates the rotation angle of the swash plate 5. By rotating the stopper 40 with respect to the front flange 10, the amount of projection of the stopper 40 with respect to the inner surface 10a side of the front flange 10 changes. Thereby, the rotation angle of the swash plate 5 is limited.

Further, a through hole 13 through which the rotary shaft 3 can pass is formed in the front flange 10. The through hole 13 is provided with a bearing 14 for rotatably supporting the other end side of the rotary shaft 3. Further, an oil seal 15 is provided in the through hole 13 at a position on the opposite side of the bearing 14 from the housing main body 9 (outside the front flange 10). The other end of the rotary shaft 3 protrudes to the outside of the front flange 10 through a bearing 14 and an oil seal 15. The oil seal 15 prevents outflow of oil from the inside, and prevents entry of foreign matter or the like from between the front flange 10 and the rotary shaft 3.

The 1 st spline 3a is formed on the other end of the rotary shaft 3 projecting through the oil seal 15. A power source such as an engine, not shown, is coupled to the rotary shaft 3 via the 1 st spline 3 a. The 2 nd spline 3b is formed on the rotating shaft 3 on the bottom 9b side of the housing body 9 with respect to the swash plate 5, that is, at the axial center of the rotating shaft 3. A cylinder 4 is fitted to a portion of the rotary shaft 3 corresponding to the 2 nd spline 3 b.

The cylinder 4 is formed in a cylindrical shape. A through hole 16 into which the rotary shaft 3 can be inserted or press-fitted is formed in the radial center of the cylinder 4. The through hole 16 is also formed with splines 16 a. The spline 16a is spline-fitted to the 2 nd spline 3b of the rotary shaft 3. Thereby, the rotary shaft 3 rotates integrally with the cylinder 4.

A recess 20 is formed around the rotation shaft 3 from the axial center to the end 4a of the through hole 16. Further, a through hole 25 penetrating the cylinder block 4 in the axial direction is formed in a part of the inner peripheral surface of the through hole 16 from the axial center to the swash plate 5 side.

In the recess 20, a spring 23 and retainers 24a, 24b discussed later are housed. A coupling member 26, which will be described later, is accommodated in the through hole 25, and the coupling member 26 is movable in the axial direction.

Further, a plurality of cylinder holes 17 are formed in the cylinder block 4 so as to surround the periphery of the rotary shaft 3. The cylinder holes 17 are arranged at equal intervals in the circumferential direction. Further, the cylinder hole 17 is formed along the axial direction, and the swash plate 5 side opens. A communication hole 18 for communicating the cylinder hole 17 with the outside of the cylinder block 4 is formed at a position corresponding to each cylinder hole 17 in an end portion 4a of the cylinder block 4 on the side opposite to the front flange 10.

A disc-shaped valve plate 19 is provided at the end 4a of the cylinder block 4 so as to overlap the end face of the end 4 a. The valve plate 19 is fixed to the housing main body 9. Even when the cylinder block 4 rotates together with the rotary shaft 3, the valve plate 19 is stationary with respect to the housing 2 (housing main body 9).

A supply/discharge port, not shown, that communicates with each communication hole 18 of the cylinder block 4 is formed in the valve plate 19 so as to penetrate through the valve plate 19 in the thickness direction. Each cylinder hole 17 and a supply port and a discharge port, not shown, formed in the housing main body 9 communicate with the communication hole 18 of the cylinder block 4 via the supply and discharge ports of the valve plates 19. The valve plate 19 is fixed to the housing main body 9, and therefore, the cylinder hole 17 is switched between a state in which the working oil is supplied from the supply port and a state in which the working oil is discharged to the discharge port via the valve plate 19 in accordance with the rotation state of the cylinder block 4.

A plunger 21 is housed in each cylinder hole 17, and the plunger 21 is slidable in the axial direction. When the plunger 21 is housed in the cylinder hole 17, the plunger 21 revolves around the center axis C1 of the rotary shaft 3 in accordance with the rotation of the rotary shaft 3 and the cylinder 4.

A spherical convex portion 28 is integrally formed at an end portion of the plunger 21 on the swash plate 5 side. In addition, the inside of the plunger 21 is formed as a cavity. The cavity is filled with the working oil in the cylinder bore 17. Thus, the reciprocating motion of the plunger 21 is associated with the supply and discharge of the working oil with respect to the cylinder bore 17. That is, when the plunger 21 is pulled out from the cylinder hole 17, the working oil is supplied from the supply port into the cylinder hole 17. When the plunger 21 enters the cylinder hole 17, the hydraulic oil is discharged from the cylinder hole 17 to the discharge port.

The spring 23 accommodated in the recess 20 of the cylinder 4 is, for example, a coil spring. The spring 23 is compressed between two holders 24a, 24b housed in the recess 20. Therefore, the spring 23 generates a biasing force in a direction to be extended by its elastic force. The biasing force of the spring 23 is transmitted to the coupling member 26 via one holder 24b of the two holders 24a, 24 b.

A cylindrical pressing member 27 is provided around the rotary shaft 3 at a position closer to the front flange 10 than the coupling member 26. The biasing force of the spring 23 received by the coupling member 26 is transmitted to the pressing member 27. The pressing member 27 presses a shoe holding member 29, which will be discussed later, toward the swash plate 5 side.

The shoes 22 are attached to the convex portions 28 of the plungers 21 accommodated in the cylinder holes 17 of the cylinder block 4, respectively. A spherical recess 22a is formed on the surface of the shoe 22 on the side of receiving the projection 28 so as to correspond to the shape of the projection 28. The convex portion 28 of the plunger 21 is fitted into the concave portion 22 a. Thereby, the shoe 22 is connected to the convex portion 28 of the plunger 21 to be rotatable.

Each shoe 22 is integrally held by a shoe holding member 29. The shoe holding member 29 is pressed toward the swash plate 5 by the pressing member 27. Then, the shoes 22 are pressed toward the swash plate 5 by the pressing members 27 via the shoe holding members 29.

Fig. 4 is a perspective view of the swash plate 5 viewed from the cylinder block 4 side. Fig. 5 is a perspective view of the swash plate 5 viewed from the front flange 10 side.

As shown in fig. 1, 4, and 5, the swash plate 5 has the following functions: rotates to incline, thereby restricting the movement of each plunger 21 in the axial direction. The swash plate 5 has a circular swash plate body 31 as viewed from the cylinder block 4 side. A through hole 32 penetrating in the axial direction is formed in the radial center of the swash plate body 31. The rotary shaft 3 penetrates the through hole 32. A flat sliding surface 31a is formed on the cylinder block 4 side of the swash plate body 31. Each shoe 22 is slidably pressed against the sliding surface 31 a.

Two support convex portions 33, 34 are disposed on the back surface side of the swash plate 31a of the swash plate body 31 so as to face each other in the radial direction about the through-hole 32. The two support convex portions 33 and 34 (the 1 st support convex portion 33 and the 2 nd support convex portion 34) are portions for rotatably supporting the swash plate 5 to the front flange 10. Each of the support convex portions 33 and 34 is formed in a semicircular shape as viewed in the radial direction, and has an arc surface 33a or 34 a. The support convex portions 33 and 34 are formed to protrude from the swash plate body 31 so that the arc surfaces 33a and 34a face the front flange 10 side.

The arcuate surfaces 33a and 34a of the support convex portions 33 and 34 slidably abut against the concave portion 30a of the swash plate support portion 30 formed to protrude from the front flange 10. The swash plate 5 rotates relative to the front flange 10 as the circular arc surfaces 33a and 34a slide in the recess 30 a. That is, the rotation axis (corresponding to the 2 nd rotation axis in the claims) C2 of the swash plate 5 is perpendicular to the center axis C1 of the rotary shaft 3 and is positioned at the arc center of the concave portion 30a and the arc surfaces 33a and 34a (see fig. 2). The swash plate 5 rotates about the rotation axis C2.

A pin hole 35 is formed in a radial outer surface 33b of the 1 st supporting convex portion 33 of the two supporting convex portions 33 and 34 substantially at the center of the outer surface 33 b. A coupling pin (corresponding to a protrusion of the claims) 36 (see fig. 7) for coupling a coupling member 68 to be described later is fixed to the pin hole 35 by press fitting or the like. In a state where the coupling pin 36 is fixed to the pin hole 35, the coupling pin 36 protrudes from the outer side surface 33b of the 1 st supporting convex portion 33 in the direction of the rotation axis C2.

Further, a guide groove 58 is formed on the outer side surface 33b of the 1 st supporting convex portion 33 from the end portion on the sliding surface 31a side to a periphery slightly beyond the pin hole 35. The guide groove 58 is a groove for guiding a connecting member 68, which will be discussed later, to the link pin 36.

Further, a 1 st biased portion 37 and a 2 nd biased portion 38 that are opposed to each other in the radial direction with the through hole 32 as the center are integrally formed on the radial side portion of the swash plate body 31. The direction in which the 1 st biased portion 37 and the 2 nd biased portion 38 face each other is orthogonal to the direction in which the two support convex portions 33 and 34 face each other.

The 1 st biased portion 37 extends radially outward from the swash plate body 31. The 1 st urged portion 37 is formed to be slightly tapered as it goes radially outward. A coupling recess 39 is formed on a surface (a surface closer to the cylinder 4) on the opposite side to the protruding direction of each of the support convex portions 33 and 34 on the radially outer side (the distal end side) of the 1 st urged portion 37. The 1 st biasing portion 6 is coupled to the coupling recess 39. The coupling recess 39 is formed in a circular shape as viewed in the axial direction. Further, a rounded portion 37a is formed at the tip of the 1 st urged portion 37. The arc center of the rounded portion 37a substantially coincides with the center of the coupling recess 39.

The 2 nd biased portion 38 extends from the swash plate body 31 toward the opposite side of the 1 st biased portion 37. The 2 nd urged portion 38 is formed in a rectangular shape as viewed in the axial direction. In the present embodiment, the surface 38a of the 2 nd urged portion 38 on the front flange 10 side abuts against the stopper 40 provided to the front flange 10.

The 2 nd biased portion 38 has a contact surface 41 formed substantially on the entire surface on the opposite side to the protruding direction of the support convex portions 33 and 34 (the surface on the cylinder 4 side). The abutment surface 41 is formed by cutting out the 2 nd biased portion 38 flatly. The 2 nd urging portion 7 abuts on the abutment surface 41.

As shown in fig. 2, the swash plate 5 configured as above rotates with respect to the front flange 10, and the 1 st biased portion 37 and the 2 nd biased portion 38 are inclined so as to approach and separate from the front flange 10. That is, the rotation angle of the swash plate 5 can be said to be an inclination angle inclined with respect to a plane orthogonal to the rotation shaft 3 of the swash plate 5.

The rotation angle (inclination angle) of the swash plate 5 is an angle formed by the sliding surface 31a and a surface perpendicular to the rotation shaft 3. That is, the smaller the angle, the smaller the rotation angle of the swash plate 5.

As shown in fig. 2, the 1 st biasing portion 6 biases the swash plate 5 in a direction in which the rotation angle of the swash plate 5 increases. The 1 st urging portion 6 includes: a 1 st holder 42 disposed on the bottom 9b side of the case body 9; a 2 nd retainer 43 disposed on the swash plate 5 side; and a 1 st spring 44 and a 2 nd spring 45 disposed between the 1 st holder 42 and the 2 nd holder 43.

A spherical coupling convex portion 43a is formed to protrude from the 2 nd retainer 43 on the swash plate 5 side. The 2 nd retainer 43 is connected to the swash plate 5 so as to be rotatable by the connection convex portion 43a coming into contact with the connection concave portion 39 of the swash plate 5.

The 1 st spring 44 is compressed between the 1 st holder 42 and the 2 nd holder 43. Therefore, the 1 st spring 44 generates a biasing force toward the direction in which the 1 st spring 44 is extended by its elastic force.

The 2 nd spring 45 is disposed inside the 1 st spring 44. Therefore, the outer diameter of the 2 nd spring 45 is smaller than that of the 1 st spring 44. The 2 nd spring 45 is fixed to the 2 nd holder 43.

The 2 nd spring 45 is spaced apart from the 1 st retainer 42 in a state where the rotation angle of the swash plate 5 is large (see fig. 2). Accordingly, when the rotation angle of the swash plate 5 is large, only the biasing force of the 1 st spring 44 acts on the swash plate 5.

In contrast, when the rotation angle of the swash plate 5 is small, the 2 nd spring 45 contacts the 1 st retainer 42 at a certain rotation angle. When the rotation angle of the swash plate 5 is further reduced, the 2 nd spring 45 is also compressed between the 1 st retainer 42 and the 2 nd retainer 43. Thereby, both the 1 st spring 44 and the 2 nd spring 45 act on the swash plate 5.

In this way, the 1 st biasing portion 6 can change its biasing force stepwise according to the rotation angle of the swash plate 5. The 2 nd spring 45 is not limited to the structure fixed to the 2 nd holder 43, and may be fixed to the 1 st holder 42. Further, the first holder 42 and the second holder 43 may be movable between the first holder 42 and the second holder 43 without being fixed to either of the first holder 42 and the second holder 43.

The 2 nd biasing unit 7 applies a biasing force in a direction opposite to the biasing force of the 1 st biasing unit 6 on the swash plate 5 to the swash plate 5. In particular, the 2 nd biasing portion 7 biases the swash plate 5 in a direction in which the rotation angle of the swash plate 5 is decreased against the biasing force in a direction in which the rotation angle of the swash plate 5 is increased by the 1 st biasing portion 6.

The 2 nd urging portion 7 includes an urging lever 46 and an urging pin unit 50. The biasing pin unit 50 mainly includes a unit case 51 and a plurality of biasing pins 52 and 53. In fig. 2, only two of the plurality of urging pins 52 and 53 are shown, and for example, 4 of the plurality of urging pins 52 and 53 are provided.

The unit case 51 is attached so as to fit into the attachment recess 48 of the case main body 9. A plurality of 2 nd guide portions 54 for guiding the plurality of urging pins 52 and 53 are provided on the swash plate 5 side of the unit case 51. The 2 nd guide 54 is a hole penetrating the unit case 51 in the axial direction. Further, a cylinder hole 55 communicating with 1 of the plurality of 2 nd guide portions 54 is provided on the opposite side of the unit case 51 from the swash plate 5. The cylinder hole 55 opens on the side of the unit case 51 opposite to the 2 nd guide 54. The opening of the cylinder hole 55 is closed by a lid member 57.

A cylindrical biasing plunger 56 is disposed in the cylinder hole 55, and the biasing plunger 56 is slidable in the axial direction relative to the cylinder hole 55.

The 2 nd guide portion 54 accommodates the respective urging pins 52, 53, and the respective urging pins 52, 53 are slidable in the axial direction.

One urging pin 52 of the plurality of urging pins 52, 53 is formed longer than the other urging pin 53. Such one urging pin 52 is housed in the 2 nd guide portion 54 communicating with the cylinder hole 55. An opposite side end of one of the urging pins 52 opposite to the swash plate 5 protrudes toward the cylinder hole 55.

For example, a signal pressure based on the hydraulic oil discharged from the hydraulic pump 1, a signal pressure from another hydraulic pump driven by the same drive source, a signal pressure corresponding to an operation of an external device such as an air conditioner driven by the same drive source, and the like are input to the 2 nd guide unit 54. A signal pressure generated by, for example, a control valve, or the like is input to the cylinder bore 55. The respective urging pins 52, 53 urge the urging lever 46 toward the swash plate 5 in accordance with signal pressures corresponding to the respective urging pins 52, 53.

The urging rod 46 is disposed between the contact surface 41 of the swash plate 5 and the respective urging pins 52 and 53. The urging rod 46 is formed in a cylindrical shape so as to be long in the axial direction, and is guided to be movable in the axial direction by the 1 st guide portion 49 of the housing main body 9.

A spherical surface 46a is formed at the end of the urging rod 46 on the abutting surface 41 side. Therefore, even if the angle formed by the swash plate 5 (contact surface 41) and the urging rod 46 changes due to a change in the rotation angle of the swash plate 5, the urging force to the swash plate 5 can be appropriately transmitted from the spherical surface 46a to the contact surface 41.

(guide recess, sensor mounting opening, and rotation angle sensor)

Fig. 6 is a perspective view showing a state where the rotation angle sensor 8 is removed from the housing main body 9.

As shown in fig. 6, the guide recess 12 formed in the housing main body 9 is formed in a region including the rotation axis C2. The guide recess 12 is formed in a quadrangular shape as viewed from the rotation axis C2 direction. Of the four sides of the guide recess 12, two opposite sides are oriented in the axial direction, and the other two opposite sides are orthogonal to the axial direction.

The sensor mounting opening 12a formed in the guide recess 12 is formed on the rotation axis C2. The sensor mounting opening portion 12a is formed in a quadrangular shape as viewed from the rotation axis C2 direction. The four sides of the sensor attachment opening 12a are also along the same direction as the direction of the four sides of the guide recess 12. That is, two of the four sides of the sensor attachment opening 12a are opposed to each other in the axial direction, and the other two opposed sides are orthogonal to the axial direction.

The rotation axis C2 of the hydraulic pump 1 and the periphery of the rotation axis C2 are exposed through the sensor mounting opening portion 12 a. That is, a part of each of the cylinder block 4, the swash plate 5, the shoe 22, the shoe holding member 29, and the plunger 21 is exposed through the sensor mounting opening portion 12 a.

A slight gap S is formed between the side surface 9c of the housing main body 9 and the outer side surface 33b of the 1 st supporting convex portion 33 of the swash plate 5. The side surface 9c of the case body 9 can be prevented from interfering with the coupling pin 36 (see fig. 7) fixed to the 1 st support convex portion 33 of the swash plate 5 by the gap S.

Further, female screw portions 60 are formed on the side surface 9c of the case main body 9 at positions corresponding to the four corners of the sensor attachment opening portion 12 a. The female screw portion 60 is a member that fixes the rotation angle sensor 8 to the housing main body 9.

Fig. 7 is a perspective view in which the rotation angle sensor 8 of fig. 3 and a part of the periphery of the rotation angle sensor 8 are cut away.

As shown in fig. 3 and 7, the rotation angle sensor 8 is provided so as to close the sensor mounting opening 12a formed in the rotation axis C2 of the swash plate 5 in the case body 9. The rotation angle sensor 8 is, for example, a potentiometer (variable resistor). The rotation angle sensor 8 includes: a 1 st rotation detection shaft (corresponding to a rotation detection shaft of claims) 61; a sensor main body 62 that detects a resistance value according to a rotation angle of the 1 st rotation detection shaft 61; and a base portion 63 for fixing the sensor main body 62 to the side surface 9c of the case main body 9. The rotation angle sensor 8 detects a resistance value according to the rotation angle of the 1 st rotation detection shaft 61, and calculates the rotation angle of the 1 st rotation detection shaft 61 based on the resistance value.

The base portion 63 is plate-shaped and formed in a quadrangular shape as viewed from the rotation axis C2 direction.

The base portion 63 is formed to be larger than the size of the sensor mounting opening portion 12a of the housing main body 9. The sensor mounting opening 12a is closed by the base portion 63. Bolt insertion holes 63a (see fig. 8) that communicate with the female screw portions 60 of the housing main body 9 are formed at four corners of the base portion 63. The bolt 64 penetrates the bolt penetration hole 63a, and the base portion 63 is fixed to the housing main body 9 by fastening the bolt 64 to the female screw portion 60 of the housing main body 9.

In a state where the base portion 63 is fixed to the case main body 9, two support walls 67 rising from both sides along the rotation axis C2 with the rotation axis C2 interposed therebetween are integrally formed on the upper surface 63b of the base portion 63 on the side opposite to the case main body 9. The sensor body 62 is placed and fixed on the two support walls 67.

Further, in a state where the base portion 63 is fixed to the housing main body 9, a cylindrical bearing housing 65 is integrally formed at a passing position of the rotation axis C2 of the base portion 63. The bearing housing 65 protrudes from the base portion 63 toward the swash plate 5 side. A flanged bearing 66 is provided in the bearing housing 65. The flanged bearing 66 is disposed such that a flange portion 66a thereof abuts against the distal end (end portion on the swash plate 5 side) of the bearing housing 65. The 1 st rotation detection shaft 61 is rotatably supported by the base portion 63 via a flanged bearing 66.

The axial center C3 of the 1 st rotation detection shaft 61 coincides with the rotation axis C2. One end 61a of the 1 st rotation detection shaft 61 on the swash plate 5 side protrudes toward the swash plate 5 side with respect to the bearing 66. The other end 61b of the 1 st rotation detection shaft 61 on the sensor body 62 side protrudes toward the sensor body 62 side with respect to the support wall 67.

A connecting member 68 is attached to one end 61a of the 1 st rotation detecting shaft 61. The connecting member 68 is a plate-shaped member that spans between the one end 61a of the 1 st rotation detecting shaft 61 and the connecting pin 36 of the swash plate 5. The thickness direction of the connecting member 68 coincides with the direction of the rotation axis C2.

A through hole 69 into which the one end 61a of the 1 st rotation detecting shaft 61 is inserted is formed in the one end 68a of the connecting member 68 on the 1 st rotation detecting shaft 61 side in the longitudinal direction. The through hole 69 penetrates in the thickness direction of the connecting member 68.

The one end 61a of the 1 st rotation detecting shaft 61 and the through hole 69 are formed so that the connecting member 68 does not rotate with respect to the 1 st rotation detecting shaft 61. For example, a part of the one end 61a is cut flat along the rotation axis C2 (D-cut). Thus, the cross-section of the one end 61a perpendicular to the rotation axis C2 is D-shaped. On the other hand, the through hole 69 is also formed in a D shape when viewed from the rotation axis C2 in accordance with the shape of the one end 61 a. By thus forming the one end 61a of the 1 st rotation detecting shaft 61 and the through hole 69, the rotation of the connecting member 68 with respect to the 1 st rotation detecting shaft 61 is prevented.

One end 61a of the 1 st rotation detection shaft 61 protrudes toward the swash plate 5 side through the through hole 69 of the connecting member 68. A retaining ring or the like, not shown, is attached to the projecting portion.

The retainer ring prevents the connecting member 68 from falling off from the 1 st rotation detecting shaft 61. The coupling member 68 is held between a flange portion 66a of the flanged bearing 66 attached to the base portion 63 and a retaining ring, not shown. Thereby, the connecting member 68 is connected so as not to be rotatable with respect to the 1 st rotation detecting shaft 61.

The member that connects the connecting member 68 so as to be non-rotatable with respect to the 1 st rotation detecting shaft 61 is not limited to the D-cut described above. The connecting member 68 may be connected so as not to rotate with respect to the 1 st rotation detecting shaft 61. For example, the connecting member 68 may be fixed to the 1 st rotation detecting shaft 61 using a bolt or the like.

A coupling groove (corresponding to a recess in the claims) 71 is formed in the other end 68b of the coupling member 68 on the coupling pin 36 side. The connecting groove 71 is formed from the other end 68b to a position slightly inward in the longitudinal direction at the center in the lateral direction of the connecting member 68. The coupling grooves 71 are formed so as to open on both sides in the thickness direction of the coupling member 68. Thereby, the other end 68b of the connecting member 68 becomes bifurcated. The coupling pin 36 is inserted into the coupling groove 71 formed in this manner, and coupled so that the coupling member 68 can rotate relative to the coupling pin 36.

The sensor mounting opening 12a formed in the housing main body 9 is formed in such a size that the connecting member 68 can penetrate the sensor mounting opening 12a in a state where the longitudinal direction of the connecting member 68 is oriented in the axial direction (the state shown in fig. 7).

The sensor main body 62 includes: a cylindrical sensor housing 72 mounted on the two support walls 67 of the base portion 63; and a detection portion 73 provided to the sensor housing 72 on the side opposite to the base portion 63.

The sensor case 72 is formed with a convex portion 72a protruding toward the base portion 63. The sensor case 72 is placed on the support wall 67 such that the projection 72a is fitted between the two support walls 67. The sensor housing 72 is fixed to the support wall 67 by bolts 80.

A receiving hole 74 is formed along the rotation axis C2 in the rotation axis C2 of the sensor housing 72. The receiving hole 74 receives a connector 76 for connecting the 1 st rotation detection shaft 61 and the detection unit 73. Further, a lead-out hole 75 communicating the radially outer side of the sensor case 72 with the receiving hole 74 is formed in the side surface of the sensor case 72. A sensor wire, not shown, extending from the detection portion 73 is drawn out through the drawing hole 75. The sensor line is connected to a control device not shown.

The detection portion 73 disposed in the sensor housing 72 has a 2 nd rotation detection shaft (corresponding to a rotation detection shaft of the claims) 77. The 2 nd rotation detecting shaft 77 is inserted into the receiving hole 74 of the sensor housing 72. The 2 nd rotation detection shaft 77 and the 1 st rotation detection shaft 61 are coupled to each other by a connector 76 housed in the sensor case 72. Thereby, the 2 nd rotation detecting shaft 77 rotates integrally with the 1 st rotation detecting shaft 61. The rotation angle of the 2 nd rotation detection shaft 77 is detected by the detection unit 73. The detection result of the detection unit 73 is output as a signal to a control device not shown via a sensor line not shown.

Further, it is desirable that the connector 76 has a centering function capable of absorbing the shaft misalignment between the 2 nd rotation detecting shaft 77 and the 1 st rotation detecting shaft 61. This allows the 2 nd rotation detecting shaft 77 and the 1 st rotation detecting shaft 61 to be appropriately coupled by the connector 76.

(mounting method of rotation Angle sensor)

Next, a method of attaching the rotation angle sensor 8 to the housing main body 9 will be described.

Fig. 8 to 10 are explanatory views showing a procedure of a method of mounting the rotation angle sensor 8. Fig. 8 to 10 correspond to fig. 7 described above.

The rotation angle sensor 8 is assembled with a 1 st rotation detection shaft 61, a sensor main body 62, and a base portion 63 in advance. Further, a connecting member 68 is attached to the 1 st rotation detection shaft 61 of the rotation angle sensor 8. In addition, the hydraulic pump 1 is assembled in advance except for the rotation angle sensor 8.

First, as shown in fig. 8, the rotation angle sensor 8 is prepared in advance in the sensor mounting opening 12a of the housing main body 9. At this time, the connecting member 68 is directed toward the sensor mounting opening 12 a. In addition, the position of the connecting member 68 is aligned with the position of the sensor mounting opening portion 12 a.

From this state, as shown in fig. 9, the rotation angle sensor 8 is lowered toward the sensor attachment opening portion 12a (see arrow Y1 in fig. 9). Then, the base portion 63 of the rotation angle sensor 8 is brought into contact with the side surface 9c of the housing main body 9. In this state, the connecting member 68 enters the inside of the housing main body 9 through the sensor mounting opening portion 12 a. The rotation axis C2 of the swash plate 5 is offset from the axial center C3 of the 1 st rotation detection shaft 61 and the 2 nd rotation detection shaft 77 in the rotation angle sensor 8. That is, the coupling pin 36 provided to the 1 st supporting convex portion 33 of the swash plate 5 is not inserted into the coupling groove 71 of the connecting member 68.

The sensor attachment opening 12a is formed to have a size that allows the connecting member 68 to pass therethrough in a state where the longitudinal direction of the connecting member 68 is oriented in the axial direction (see fig. 8 and 9). Therefore, the housing main body 9 does not interfere with the connecting member 68.

In fig. 9, although not shown, in a state where the rotation angle sensor 8 is lowered toward the sensor attachment opening 12a, one side 12b of the step formed around the guide recess 12 abuts one side 63c (any one of the sides 12b, 63c is also referred to fig. 3) of the base portion 63.

Next, as shown in fig. 10, the rotation angle sensor 8 is slid toward the front flange 10 side (see arrow Y2 in fig. 10). At this time, the base portion 63 may be slid along the side 12c of the guide concave portion 12. Here, the guide recess 12 is formed in a quadrangular shape as viewed from the rotation axis C2 direction. Of the four sides of the guide recess 12, two opposite sides are oriented in the axial direction, and the other two opposite sides are orthogonal to the axial direction. Therefore, the rotation angle sensor 8 can be easily slid in the axial direction along the one side 12c of the guide recess 12. In this way, the guide recess 12 functions as a guide for sliding the rotation angle sensor 8 during assembly.

When the rotation angle sensor 8 is slid toward the front flange 10 side, the connecting member 68 enters the gap S between the side surface 9c of the housing main body 9 and the outer side surface 33b of the 1 st supporting convex portion 33 of the swash plate 5 (see fig. 6). Then, the coupling pin 36 provided to the 1 st supporting convex portion 33 is inserted into the coupling groove 71 of the connecting member 68.

At this time, since the guide groove 58 is formed on the outer side surface 33b of the 1 st support convex portion 33 from the end portion on the sliding surface 31a side to the periphery slightly beyond the pin hole 35, the connecting member 68 is guided by the guide groove 58. Therefore, even when the position of the coupling pin 36 cannot be visually checked by the housing main body 9, the coupling pin 36 can be easily inserted into the coupling groove 71 of the connecting member 68.

Further, by sliding the rotation angle sensor 8 toward the front flange 10 side, the other side 12c of the step formed around the guide recess 12 abuts against the other side 63d of the base portion 63. Thereby, the rotation angle sensor 8 is positioned with respect to the housing main body 9. In this way, the guide recess 12 also has a function of positioning the rotation angle sensor 8 with respect to the housing main body 9.

When the rotation angle sensor 8 is positioned with respect to the housing main body 9, the rotation axis C2 of the swash plate 5 is aligned with the axial center C3 of the 1 st rotation detection shaft 61 (the 2 nd rotation detection shaft 77) in the rotation angle sensor 8.

As a method of positioning the rotation axis C2 and the shaft center C3, for example, the following methods are available: the guide recess 12 is not formed, and the female screw portion 60 of the housing main body 9 and the bolt insertion hole 63a of the base portion 63 are aligned. The method is not limited to these methods, and alignment between the rotation axis C2 and the axial center C3 may be performed. For example, a positioning projection or the like may be provided on the side surface 9C of the housing main body 9, and the rotation axis C2 and the axial center C3 may be aligned by bringing the one side 63d of the base portion 63 into contact with the projection. In a state where the rotation axis C2 and the shaft center C3 are aligned, the sensor attachment opening portion 12a of the case main body 9 is closed by the base portion 63.

Next, as shown in fig. 7, the bolt 64 is inserted through the bolt insertion hole 63a of the base portion 63. Then, the bolt 64 is fastened to the female screw portion 60 of the housing main body 9. Thereby, the base portion 63 is fixed to the housing main body 9, and the mounting of the rotation angle sensor 8 to the housing main body 9 is completed.

(operation of Hydraulic Pump)

Next, the operation of the hydraulic pump 1 will be described.

The hydraulic pump 1 outputs a driving force based on discharge of the hydraulic oil from the cylinder holes 17 (and supply of the hydraulic oil to the cylinder holes 17).

More specifically, first, the rotary shaft 3 is rotated by power from a power source such as an engine, and the cylinder block 4 and the rotary shaft 3 are rotated integrally. With the rotation of the cylinder 4, the plunger 21 revolves orbitally around the center axis C1 of the rotary shaft 3.

The shoes 22 attached to the convex portions 28 of the plungers 21 are pressed against the sliding surface 31a of the swash plate 5 by appropriately following the sliding surface 31a of the swash plate 5 by the biasing force of the spring 23 regardless of the rotation angle of the swash plate 5. The convex portion 28 of the plunger 21 is formed in a spherical shape, and the concave portion 22a of the shoe 22 into which the convex portion 28 is fitted is also formed in a spherical shape. Therefore, even if the rotation angle of the swash plate 5 changes, the shoes 22 follow the inclination of the swash plate 5 and appropriately follow the sliding surface 31a, and are pressed against the sliding surface 31 a.

When the plunger 21 revolves around the center axis C1 of the rotary shaft 3 as the cylinder block 4 rotates, the shoes 22 slide on the sliding surface 31a of the swash plate 5 while revolving around the center axis C1 of the rotary shaft 3. Thereby, each plunger 21 slides in the axial direction in each cylinder bore 17, and each plunger 21 reciprocates. In this way, the swash plate 5 restricts the movement of each plunger 21 in the axial direction. By the reciprocating operation of the plunger 21, the hydraulic oil is discharged from some of the cylinder holes 17, and the hydraulic oil is sucked into the other cylinder holes 17, whereby the hydraulic pump is realized.

However, when the rotation angle of the swash plate 5 (sliding surface 31a) changes, the stroke (sliding distance) of the reciprocating motion of the plunger 21 changes. That is, the greater the rotation angle of the swash plate 5, the greater the supply amount and discharge amount of the hydraulic oil to the cylinder bores 17 accompanying the reciprocating motion of the respective plungers 21. On the other hand, the smaller the rotation angle of the swash plate 5, the smaller the supply amount and discharge amount of the hydraulic oil to the cylinder bores 17 accompanying the reciprocating motion of the respective plungers 21. When the rotation angle of the swash plate 5 is 0 degrees, the plungers 21 do not reciprocate even if the plungers 21 revolve around the center axis C1 of the rotary shaft 3.

Therefore, the discharge amount of the hydraulic oil from each cylinder hole 17 is also zero.

Further, a male screw-shaped stopper 40 is provided on the front flange 10 on the radially outer side. Therefore, when the rotation angle of the swash plate 5 is reduced, the swash plate 5 abuts on the stopper 40. The stopper 40 can advance and retreat with respect to the swash plate 5 by rotating the swash plate 5. Therefore, by advancing and retracting the stopper 40 with respect to the swash plate 5, the minimum rotation angle of the swash plate 5 can be appropriately adjusted.

Next, the rotation operation of the swash plate 5 will be described.

The swash plate 5 is biased by the 1 st biasing portion 6 in a direction in which the rotation angle of the swash plate 5 increases. The swash plate 5 is biased by the 2 nd biasing portion 7 in a direction in which the rotation angle of the swash plate 5 is reduced. The swash plate 5 is inclined and stopped at a position where the magnitude of the torque (counterclockwise torque in fig. 2, hereinafter, abbreviated as "counterclockwise torque") around the rotation axis C2 of the swash plate 5 generated by the biasing force of the 1 st biasing unit 6 is equal to the magnitude of the torque (clockwise torque in fig. 2, hereinafter, abbreviated as "clockwise torque") around the rotation axis C2 of the swash plate 5 generated by the 2 nd biasing unit 7.

That is, when the clockwise torque generated by the 2 nd biasing portion 7 is increased, the rotation angle of the swash plate 5 is decreased. Accordingly, the 1 st spring 44 and the 2 nd spring 45 of the 1 st urging portion 6 are compressed, and the counterclockwise torque generated by the 1 st urging portion 6 also increases. Thus, the clockwise torque generated by the 2 nd biasing portion 7 is equal to the counterclockwise torque generated by the 1 st biasing portion 6, and the swash plate 5 is stopped at a predetermined inclination.

On the other hand, when the clockwise torque generated by the 2 nd biasing unit 7 is reduced, the biasing forces of the 1 st spring 44 and the 2 nd spring 45 of the 1 st biasing unit 6 dominate, and the rotation angle of the swash plate 5 increases. Accordingly, when the 1 st spring 44 and the 2 nd spring 45 are extended, the biasing force generated by the 1 st biasing portion 6 is reduced. Thus, the clockwise torque generated by the 2 nd biasing portion 7 is equal to the counterclockwise torque generated by the 1 st biasing portion 6, and the swash plate 5 is stopped at a predetermined inclination.

When the clockwise torque generated by the 2 nd urging unit 7 is changed, the urging force of the urging lever 46 on the swash plate 5 is changed. That is, for example, a signal pressure based on the hydraulic oil discharged from the hydraulic pump 1, a signal pressure from another hydraulic pump driven by the same drive source, a signal pressure corresponding to an operation of an external device such as an air conditioner driven by the same drive source, and the like are input to the 2 nd guide portion 54 of the 2 nd biasing portion 7. A signal pressure generated by, for example, a control valve, or the like is input to the cylinder bore 55. The urging pins 52 and 53 urge the urging rod 46 in accordance with the magnitude of the signal pressure. Thereby, the urging force of the urging lever 46 against the swash plate 5 changes.

The respective signal pressures are controlled based on an output signal of a control device (not shown) so that a desired rotation angle of the swash plate 5 (discharge amount of the hydraulic oil from the hydraulic pump 1) does not deviate from an actual rotation angle of the swash plate 5. An output signal of the control device is generated based on the operation signal and a rotation angle detection signal of the swash plate 5 by the rotation angle sensor 8. The operation signal is, for example, an output signal when an operation unit (not shown) of the construction machine 100 (see fig. 1) is operated.

(detection operation of rotation Angle sensor)

Next, an operation of detecting the rotation angle of the swash plate 5 by the rotation angle sensor 8 will be described.

As described above, the swash plate 5 rotates about the rotation axis C2. When the swash plate 5 rotates, the connecting pin 36 attached to the swash plate 5 swings about the rotation axis C2. The oscillation thereof is transmitted to the connecting member 68 whose other end 68b is rotatably connected to the connecting pin 36. One end 68a of the connecting member 68 is non-rotatably coupled to the 1 st rotation detecting shaft 61 located on the same axis as the rotation axis C2. Therefore, the connecting member 68 follows the connecting pin 36 of the swash plate 5 and swings about the rotation axis C2.

The 1 st rotation detecting shaft 61 to which the link member 68 is attached is integrated with the link member 68, and therefore rotates in accordance with the swing of the link member 68. The rotation of the 1 st rotation detecting shaft 61 is transmitted to the 2 nd rotation detecting shaft 77 via the connector 76. The resistance value of the detection unit 73 changes as the 2 nd rotation detection shaft 77 rotates. The rotation angle of the 1 st rotation detection shaft 61 is calculated based on the resistance value. Since the axial center C3 of the 1 st rotation detection shaft 61 coincides with the rotation axis C2, the calculated rotation angle of the 1 st rotation detection shaft 61 becomes the rotation angle of the swash plate 5. Thereby, the detection of the rotation angle of the swash plate 5 by the rotation angle sensor 8 is completed. A control device (not shown) controls the rotation angle of the swash plate 5 based on the detection result of the rotation angle sensor 8 (output of the rotation angle sensor 8).

Further, it is desirable that the position of the coupling pin 36 is as far away from the rotation axis C2 as possible. The farther from the rotation axis C2, the greater the displacement amount of the connecting pin 36 caused by the rotation of the swash plate 5.

As a result, the amount of oscillation of the connecting member 68 increases, and therefore, the rotational angle detection accuracy of the swash plate 5 by the rotational angle sensor 8 can be improved.

As described above, the above embodiment includes: a swash plate 5 that rotates within the casing 2 about a rotation axis C2; a connecting pin 36 fixed to the swash plate 5; a rotation angle sensor 8 that detects a rotation angle of the swash plate 5; and a connecting member 68 that spans the connecting pin 36 and the 1 st rotation detection shaft 61 of the rotation angle sensor 8. The rotation of the swash plate 5 is transmitted to the 1 st rotation detecting shaft 61 by the connecting member 68. That is, the connecting member 68 has a function of outputting the rotation angle of the swash plate 5 to the 1 st rotation detecting shaft 61.

With this configuration, the rotational angle (inclination angle) of the swash plate 5 is not directly detected, but the position (swing angle) of the connecting member 68 may be detected by the rotational angle sensor 8.

Therefore, the manufacturing cost of the hydraulic pump 1 can be suppressed with a simple structure without a large-scale sensor. The connecting member 68 is a plate-shaped member and has a simple structure, and therefore, the manufacturing cost of the hydraulic pump 1 can be reduced accordingly.

Further, since the rotation angle of the swash plate 5 is controlled based on the detection result of the rotation angle sensor 8 (the output of the rotation angle sensor 8), the swash plate 5 can be moved with high accuracy.

Further, since the rotation of the swash plate 5 is detected by the connecting member 68, the layout of the rotation angle sensor 8 can be improved. Therefore, the hydraulic pump 1 can be prevented from unnecessarily increasing in size, and can be made smaller.

Further, by using the connecting member 68, the axial center C3 of the 1 st rotation detecting shaft 61 in the rotation angle sensor 8 can be made to coincide with the rotation axis C2 of the swash plate 5. Since the rotation angle of the swash plate 5 can be detected on the rotation axis C2 of the swash plate 5, the rotation angle of the swash plate 5 can be detected with higher accuracy.

In addition, a potentiometer is used as the rotation angle sensor 8. Therefore, the cost of the rotation angle sensor 8 is reduced as much as possible, compared to a case where an optical sensor or the like is used as the rotation angle sensor 8, for example.

In order to couple the connecting member 68 and the swash plate 5, the coupling pin 36 is fixed to the swash plate 5, and a coupling groove 71 into which the coupling pin 36 is inserted is formed in the other end 68b of the connecting member 68. Therefore, the swash plate 5 and the connecting member 68 can be rotatably coupled with a simple structure.

When the rotation angle sensor 8 is attached to the housing main body 9, the rotation angle sensor 8 may be slid and moved so that the connecting member 68 is inserted into the connecting pin 36. Therefore, the mounting of the rotation angle sensor 8 to the housing main body 9 can be facilitated.

Since the guide groove 58 is formed in the outer side surface 33b of the 1 st support convex portion 33 of the swash plate 5, the connecting member 68 is guided by the guide groove 58. Therefore, even when the position of the coupling pin 36 cannot be visually checked by the housing main body 9, the coupling pin 36 can be easily inserted into the coupling groove 71 of the connecting member 68.

A sensor mounting opening 12a is formed in the side surface 9c of the housing main body 9, and the rotation angle sensor 8 is mounted so as to close the sensor mounting opening 12 a. With this configuration, the rotation angle sensor 8 with the connecting member 68 attached thereto can be easily assembled to the housing main body 9. The sensor mounting opening 12a can be easily closed only by mounting the rotation angle sensor 8 to the housing main body 9.

Further, since the guide concave portion 12 is formed in the side surface 9c of the housing main body 9, the rotation angle sensor 8 can be easily positioned with respect to the housing main body 9 by the guide concave portion 12.

Further, the sensor mounting opening 12a is formed on the rotation axis C2 of the swash plate 5. Therefore, the rotation angle sensor 8 can be easily attached to the rotation axis C2. As a result, the rotation axis line C2 can be easily aligned with the axial center C3 of the 1 st rotation detection shaft 61 in the rotation angle sensor 8. Therefore, the rotational angle of the swash plate 5 can be detected with high accuracy while facilitating the mounting of the rotational angle sensor 8.

The present invention is not limited to the above-described embodiments, and various modifications may be made to the above-described embodiments without departing from the scope of the present invention.

For example, in the above-described embodiment, the description has been given of the case where the construction machine 100 is a hydraulic excavator. However, the hydraulic pump 1 is not limited to being applied to a hydraulic excavator, and the hydraulic pump 1 described above can be applied to various construction machines.

In the above-described embodiment, the case where the rotation angle sensor 8 is a potentiometer has been described. However, the rotation angle sensor 8 is not limited to a potentiometer, and various sensors capable of detecting the rotation angle of the swash plate 5 can be used as the rotation angle sensor 8. The swash plate 5 is provided with a member for outputting the rotation angle of the swash plate 5, and the member is detected by a sensor.

In the present embodiment, the connecting member 68 is provided as a member for outputting the rotation angle of the swash plate 5. In the case where, for example, an optical sensor is used as the rotation angle sensor 8, a plate or the like on which an optical pattern has been formed may be provided in place of the connecting member 68 on the inclined plate 5, and the plate may be detected by the optical sensor. The connecting member 68 may be fixed to an arbitrary portion of the swash plate 5, and the position of the connecting member 68 may be detected by a proximity sensor or the like. Even in the case of the above-described configuration, the same effects as those of the above-described embodiment can be obtained.

In the above-described embodiment, the case where the guide recess 12 and the sensor attachment opening 12a are formed in a quadrangular shape as viewed from the direction of the rotation axis C2 of the swash plate 5 has been described. However, the present invention is not limited to this embodiment, and the shapes of the guide recess 12 and the sensor attachment opening 12a can be determined arbitrarily. When the guide recess 12 is formed in a shape other than a square shape, for example, as described above, the rotation axis line C2 and the axis C3 of the 1 st rotation detection shaft 61 (the 2 nd rotation detection shaft 77) in the rotation angle sensor 8 may be positioned by, for example, positioning between the female screw portion 60 of the housing main body 9 and the bolt insertion hole 63a of the base portion 63.

In the above embodiment, the following case is explained: in order to rotatably couple the connecting member 68 to the swash plate 5, the connecting pin 36 is fixed to the swash plate 5, and a coupling groove 71 into which the connecting pin 36 can be inserted is formed in the connecting member 68. However, the present invention is not limited to this embodiment, and the connecting member 68 may be rotatably coupled to the swash plate 5. For example, the connecting pin 36 may be fixed to the connecting member 68, and a recess into which the connecting pin 36 can be inserted may be formed in the swash plate 5. Instead of the coupling groove 71, a recess may be formed in the coupling member 68, and the coupling pin 36 fixed to the swash plate 5 may be inserted into the recess. The connecting pin 36 is not required, and may be a projection projecting from the swash plate 5 or the connecting member 68.

In the above-described embodiment, the case where the connecting member 68 is a plate-shaped member that extends between the one end 61a of the 1 st rotation detecting shaft 61 and the connecting pin 36 of the swash plate 5 has been described. However, the present invention is not limited to this embodiment, and any shape may be adopted as long as the swash plate 5 and the 1 st rotation detection shaft 61 can be coupled to each other.

In the above-described embodiment, the case where the rotation axis C2 of the swash plate 5 is orthogonal to the center axis C1 of the rotary shaft 3 is described. However, it is not necessary to precisely make the center axis C1 orthogonal to the rotation axis C2. The angle formed by the central axis C1 and the rotation axis C2 may be 90 degrees or more, or may be smaller than 90 degrees.

In the above embodiment, the following case is explained: the sensor attachment opening 12a formed in the side surface 9C of the case main body 9 is positioned on the rotation axis C2 of the swash plate 5, and the axis C3 of the 1 st rotation detection shaft 61 (the 2 nd rotation detection shaft 77) of the rotation angle sensor 8 coincides with the rotation axis C2. However, the present invention is not limited to this embodiment, and the sensor attachment opening 12a may be formed at a position offset from the rotation axis C2 of the case main body 9. The axial center C3 of the 1 st rotation detection shaft 61 (the 2 nd rotation detection shaft 77) may not coincide with the rotation axis C2.

The rotation angle of the swash plate 5 can be detected by the swash plate rotation angle output unit (the connecting member 68), and the sensor (the rotation angle sensor 8) can be attached to the housing 2.