JP2000220569A - Hydraulic rotating machine of variable displacement swash plate type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the workability of assembling and to miniaturize a device by using the components of a tilting and rotating actuator in common and reducing the number of part items. SOLUTION: The casing main body 2 of a casing 1 is provided with one tilting and rotating actuator 32 positioned in one side of the diameter direction of a cylinder block 5 among the tilting and rotating directions of a swash plate 31, and the other tilting and rotating actuator 33 positioned in the other side of the diameter direction. One tilting and rotating actuator 32 is composed of a single cylinder hole 32A, a tilting and rotating control piston 32B, a control pressure chamber 32C and a spring 32D, and the other tilting and rotating actuator 33 is each composed of two cylinder holes 33A, two tilting and rotating control pistons 33B, and the like. The tilting and rotating control pistons 32B and 33B are made of identical piston materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement type swash plate type hydraulic rotary machine suitably used as a variable displacement type hydraulic pump or hydraulic motor in a construction machine such as a hydraulic excavator.

[0002]

2. Description of the Related Art In general, a swash plate is tilted and driven by a tilt actuator so that a discharge capacity is variable in the case of a hydraulic pump and a rotational speed and a torque are variably controlled in a hydraulic motor. A variable displacement swash plate type hydraulic rotary machine described above is known.

[0003] A variable displacement type swash plate type hydraulic rotary machine according to the prior art will be described with reference to Figs. 5 and 6 by taking as an example a case where this type is used as a variable displacement type swash plate type hydraulic pump.

In FIG. 1, reference numeral 1 denotes a casing of a hydraulic pump. The casing 1 has a stepped tubular casing body 2 having one end serving as a closed end 2A and the other end serving as an open end 2B.
And a lid 3 as a front casing that closes the opening end 2B side of the casing main body 2.
A cylinder hole 14A, 1 of a tilt actuator 14, 15 which will be described later is located at a radially intermediate portion of the casing body 2 in the longitudinal direction of the cylinder block housing hole 2C.
5A are formed.

Reference numeral 4 denotes a rotating shaft rotatably provided in the casing 1 via a bearing or the like. One end of the rotating shaft 4 is rotatably attached to the closed end 2A side of the casing body 2,
The other end protrudes from the lid 3 to the outside. A motor such as a diesel engine is connected to the protruding end 4A of the rotating shaft 4 via a power transmission mechanism (both not shown), whereby the rotating shaft 4 is driven to rotate from the outside.

Reference numeral 5 denotes a cylinder block provided in the cylinder block receiving hole 2C of the casing main body 2 via the rotary shaft 4. The cylinder block 5 is spline-coupled to the outer peripheral side of the rotary shaft 4 in the casing 1 to rotate. It is driven to rotate integrally with the shaft 4. A plurality of cylinders 6 (only one is shown) extending in the axial direction are drilled around the rotation shaft 4 in the cylinder block 5, and one end of each cylinder 6 is in sliding contact with a switching valve plate 7 described later. It is.

A switching valve plate 7 is fixed to the closed end 2A side of the casing body 2 so as to be in sliding contact with the cylinder block 5. The switching valve plate 7 has a pair of supply / discharge ports 7 in the form of eyebrows.
A and 7B are formed, and between the supply and discharge ports 7A and 7B, a shaft insertion hole 7C for the rotary shaft 4 is located at the center side of the switching valve plate 7.
Are drilled.

[0008] 8A, 8B is a closed end 2 of the casing body 2
A shows a pair of supply / discharge passages formed on the A side.
A and 8B communicate with supply / discharge ports 7A and 7B of the switching valve plate 7, and in accordance with rotation of the cylinder block 5, hydraulic oil in a tank 17 (see FIG. 6) described later is sucked into each cylinder 6, and The pressure oil pressurized in each cylinder 6 is discharged to the outside.

Are pistons slidably inserted into the respective cylinders 6 of the cylinder block 5. The respective pistons 9 reciprocate in the respective cylinders 6 as the cylinder block 5 rotates. The operating oil is sucked into the respective cylinders 6 from the switching valve plate 7 side, and is pressurized to high-pressure oil in the respective cylinders 6. A shoe 10 is attached to an end of each piston 9 projecting from each cylinder 6 so as to be swingable, and each shoe 10 is an annular shoe holder 1.
1 and the like is pressed toward the swash plate 12 described later.

Here, each piston 9 reciprocating in each cylinder 6 is at a bottom dead center position at a position above the rotary shaft 4 as shown in FIG. Become. While the cylinder block 5 makes one rotation, each piston 9 slides in each cylinder 6 from top dead center to bottom dead center, and slides from bottom dead center to top dead center. That is, the discharge stroke that is dynamically displaced is repeated.

That is, in the suction stroke of the piston 9 corresponding to a half rotation of the cylinder block 5, the supply / discharge passages 8A, 8B
Of these, for example, hydraulic oil is sucked into each cylinder 6 through the supply / discharge port 7A of the switching valve plate 7 from the supply / discharge passage 8A on the suction side. Further, in the discharge stroke of the piston 9 corresponding to the remaining half rotation of the cylinder block 5, each piston 9 is pushed into each cylinder 6, and the hydraulic oil sucked into each cylinder 6 in the suction stroke Press. The hydraulic oil pressurized in each cylinder 6 becomes high-pressure oil and is discharged from the supply / discharge port 7B side of the switching valve plate 7 to the outside through the supply / discharge passage 8B.

Reference numeral 12 denotes a swash plate provided on the cover 3 side of the casing 1 so as to be tiltable, and the swash plate 12 has one side (front side).
A smooth surface 12A for slidably guiding each shoe 10 is provided, and a shaft insertion hole 12B for the rotating shaft 4 is formed in the center thereof. The swash plate 12 is formed with a pair of legs 12C (only one is shown) on both left and right sides of the shaft insertion hole 12B, and the surface side of each leg 12C forms a part of the smooth surface 12A. ing. The rear surface of each leg 12C is a convex curved surface 12D protruding toward the tilt support member 13 described below, and each convex curved surface 12D is formed with a constant radius of curvature.

Reference numeral 13 denotes a tilting support member provided on the cover 3 of the casing 1 located on the back side of the swash plate 12. The tilting support member 13 is formed of a material having high wear resistance. The side has a shaft insertion hole 13A through which the rotating shaft 4 is inserted. The tilt support member 13 has a shaft insertion hole 13A.
A pair of concave curved surface portions 13B (only one is shown) are provided on both the left and right sides of the swash plate 12. Each concave curved surface portion 13B is an arc surface having a constant radius of curvature corresponding to the convex curved surface 12D of the swash plate 12. Is formed.

Here, each leg 12C of the swash plate 12 has a convex curved surface 12D in each concave curved surface 13B of the tilt support member 13.
The swash plate 12 is tilted in the directions indicated by arrows A and B in FIG. And the swash plate 12
When the tilting drive is performed in the direction indicated by the arrow A, the tilt angle increases, thereby increasing the stroke amount of each piston 9 with respect to each cylinder 6 and increasing the pump capacity (pressure oil discharge amount). Further, when the swash plate 12 is tilted and driven in the direction of arrow B to reduce the tilt angle, the stroke of each piston 9 with respect to each cylinder 6 is shortened, so that the pump capacity is reduced.

Reference numerals 14 and 15 denote tilt actuators for tilting the swash plate 12, respectively.
The first and second cylinder holes 14A, 15A formed in the casing main body 2 so as to sandwich the cylinder block 5 from the radial outside in the tilting direction of the swash plate 12, and the cylinder holes 14A, 15A. The first and second tilt control pistons 14B and 15B, which are slidably inserted therein and project from the cylinder holes 14A and 15A, have spherical ends.

As shown in FIG. 5, the tilt actuators 14 and 15 have first and second control pressure chambers 14C and 15C between the cylinder holes 14A and 15A and the tilt control pistons 14B and 15B. Have been. The control pressure chambers 14 </ b> C and 15 </ b> C are supplied with the tilt control pressure through a displacement control valve 21, which will be described later, so that the tilt control piston 14 </ b> C is formed.
B and 15B are advanced and retracted from the cylinder holes 14A and 15A toward the swash plate 12 side.

In this case, the tilt control piston 15B (cylinder hole 15A) is formed to have a larger diameter than the tilt control piston 14B (cylinder hole 14A), and the tilt control piston 15B is tilted by the pressure receiving area difference. Control piston 14B
A larger tilt driving force is generated. In the control pressure chambers 14C and 15C, the bottoms of the cylinder holes 14A and 15A and the tilt control pistons 14B and 15C are provided.
B, first and second springs 14D, 15D are disposed, and the springs 14D, 15D constantly urge the tilt control pistons 14B, 15B in a direction to protrude from the cylinder holes 14A, 15A. .

Further, the tilt control pistons 14B, 15B
The swash plate 12 is disposed on the surface of the swash plate 12 so as to sandwich the cylinder block 5 from the outside in the radial direction, and the spherical end thereof is always in contact with the swash plate 12. And the tilt control piston 1
Reference numerals 4B and 15B drive the swash plate 12 in the directions indicated by arrows A and B in FIG. 5 according to the tilt control pressure supplied and discharged into the control pressure chambers 14C and 15C.

Next, reference numeral 16 denotes a pilot pump serving as a generation source of the tilt control pressure. The pilot pump 16 sucks hydraulic oil in a tank 17 as shown in FIG.
The tilt control pressure is supplied to the inside. A branch pipe 19 is provided at an intermediate portion of the control pipe 18, and the branch pipe 19 connects the control pressure chamber 14 </ b> C of the tilt actuator 14 to the pilot pump 16 through the control pipe 18.

Reference numeral 20 denotes another control line connected to the control pressure chamber 15C of the tilt actuator 15, and reference numeral 21 denotes the control line 1.
The displacement control valve is provided between the displacement control valves 8 and 20.
Is composed of, for example, a 3-port 3-position hydraulic pilot type servo valve, etc., and switches from the neutral position (a) to the switching positions (b), (c) according to the tilt control pilot pressure supplied to the hydraulic pilot section 21A. ).

Here, when the displacement control valve 21 is switched from the neutral position (a) to the switching position (b) against the spring 21B, the control lines 18, 20 and the branch line 19 are both piloted. Connected to the pump 16, the control pressure chambers 14C, 1
The tilt control pressure from the pilot pump 16 is supplied into 5C. At this time, the insides of the control pressure chambers 14C and 15C are in the same pressure state. However, since the tilt control piston 15B has a larger pressure receiving area than the tilt control piston 14B, a larger tilt drive is performed. A force can be generated, and the swash plate 12 is driven by the tilt control piston 15B in the direction of arrow A to the large tilt side.

When the displacement control valve 21 is switched from the neutral position (A) to the switching position (C), the control pressure chamber 15C
Is connected to the tank 17 via the control line 20, and the control pressure chamber 14 </ b> C is connected to the pilot pump 16 via the control line 18 and the branch line 19. Therefore, the control pressure chamber 1
The tilt control pressure from the pilot pump 16 is supplied only in 4C, and the swash plate 12 is driven by the tilt control piston 14B in the direction of the arrow B to the small tilt side. When the displacement control valve 21 returns to the neutral position (a), the control lines 18, 20 and the branch line 19 are both connected to the tank 17, and the pressure in the control pressure chambers 14C, 15C is reduced to the tank pressure level. Will decrease.

Reference numeral 22 denotes a feedback link provided between the control sleeve 21C of the displacement control valve 21 and the swash plate 12. The feedback link 22 moves the control sleeve 21C following the tilting operation of the swash plate 12. The displacement is slid and feedback control of the capacity control valve 21 is performed.

The variable displacement type swash plate type hydraulic pump according to the prior art has the above-described configuration, and its operation will be described below.

First, when the rotating shaft 4 is driven to rotate by the prime mover, the cylinder block 5 rotates integrally with the rotating shaft 4, so that each piston 9 reciprocates in each cylinder 6, and each piston 9 performs a suction stroke. And the discharge process are sequentially repeated. During this time, each shoe 10 slides on the smooth surface 12A of the swash plate 12 so as to draw a ring-like trajectory, thereby compensating the reciprocating motion of the piston 9 in each cylinder 6.

When changing the pump displacement as a variable displacement hydraulic pump, the tilt actuator 1
The swash plate 12 is tilted by the tilt control pistons 14B and 15B in the directions indicated by arrows A and B in FIG.
2 is changed. The stroke of each piston 9 in each cylinder 6 increases or decreases in accordance with the tilt angle of the swash plate 12, whereby the pump displacement is variably controlled.

In this case, the tilt control pistons 14B, 15
B are formed of different piston members, and the tilt control piston 15B is formed to have a larger diameter than the tilt control piston 14B, so that the displacement control valve 21 shown in FIG.
Is switched to the switching position (b), the tilt control pressure from the pilot pump 16 is applied to the tilt actuators 14 and 1.
The swash plate 12 is driven by the large-diameter tilt control piston 15B in the direction of arrow A to the large tilt side, despite being supplied to both the control pressure chambers 14C and 15C.

When the displacement control valve 21 is switched to the switching position (C), the control pressure chamber 15C is connected to the tank 17 via the control line 20, and only the control pressure chamber 14C is connected to the control line 18 and the branch. Pilot pump 1 via line 19
6, the tilt control pressure from the pilot pump 16 is supplied only into the control pressure chamber 14C, and the swash plate 12 is driven by the tilt control piston 14B in the direction of arrow B to the small tilt side. You.

When adjusting the tilt angle of the swash plate 12 by continuously changing it, the displacement control valve 21 is repeatedly switched between the neutral position (a) and the switching positions (b) and (c). By doing so, the tilt control pistons 14B and 15B are selectively moved forward and backward, and the tilt angle of the swash plate 12 is set to an arbitrary tilt position between the maximum tilt angle and the minimum tilt angle. It is automatically controlled.

[0030]

In the prior art described above, the tilt actuators 14 and 15 have different diameters from each other, and the second tilt control piston 1
5B is formed to have a larger diameter than the first tilt control piston 14B, so that the components of the tilt actuators 14 and 15 cannot be shared, not only the number of components increases, but also component management. However, there is a problem that the work becomes complicated and the workability at the time of assembly is also reduced.

Further, as shown in FIG. 5, since the tilt control piston 15B of the tilt actuator 15 and the like are formed to have a large diameter by a single piston member, it is difficult to reduce the size of the casing 1 of the hydraulic pump. However, there is a problem that it becomes an obstacle when the whole apparatus is downsized.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to reduce the number of parts and improve the workability during assembly by sharing the components of the tilt actuator. An object of the present invention is to provide a variable displacement type swash plate type hydraulic rotary machine capable of improving the size and reducing the size of the entire apparatus by making it compact.

[0033]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a casing, a rotating shaft rotatably provided in the casing, and a plurality of cylinders extending in the axial direction. A cylinder block provided integrally with the rotary shaft in the casing, a plurality of pistons reciprocally inserted into respective cylinders of the cylinder block, and mounted on protruding ends of the respective pistons. And a swash plate whose front side is a smooth surface that guides each shoe slidably and whose back side is supported to be tiltable with respect to the casing, and a tilt actuator that tilts and drives the swash plate. Applied to a variable capacity swash plate type hydraulic rotary machine consisting of

A feature of the structure adopted in the first aspect of the present invention is that the tilt actuator is displaced to the casing at one radial position of the tilt direction of the swash plate with respect to the rotation axis. A first tilt control piston that is provided so as to be capable of contacting the swash plate at the tip end, and is displaceable to the casing at a position on the other side in the radial direction of the tilt direction of the swash plate that sandwiches the rotation axis. It is provided with a plurality of second tilt control pistons that are provided and whose leading end contacts the swash plate.

With this configuration, for example, 2
The second tilt control piston including the two piston members
When a tilt drive force can be generated larger than that of the first tilt control piston composed of a single piston member, and the tilt control pressure is supplied to both the tilt control pistons, the second tilt control is performed. The swash plate can be tilted and driven to the large tilt side by the piston. When the tilt control pressure is supplied only to the first tilt control piston, the swash plate can be tilted to the small tilt side by the first tilt control piston.

According to the second aspect of the present invention, the first and second tilt control pistons are constituted by substantially the same piston members. Thus, the first and second tilt control pistons can be formed by a common piston member, and components can be shared.

On the other hand, the feature of the structure adopted by the invention of claim 3 is that the tilt actuator is provided at the first and second positions provided on one side and the other side in the tilt direction of the swash plate with respect to the rotary shaft. A second cylinder hole and first and second ends slidably inserted into the first and second cylinder holes and having ends protruding from the first and second cylinder holes abutting on the swash plate; Tilt control piston, the first and second tilt control pistons, and the first and second tilt control pistons.
The first and second tilt control pistons are formed between the first and second cylinder holes when the tilt control pressure is supplied and discharged from the outside. 2
And a first and second biasing member disposed in the first and second control pressure chambers and constantly biasing the first and second tilt control pistons toward the swash plate. And the first and second cylinder holes are formed in different numbers from each other, and the first and second tilt control pistons and the first and second biases provided in each of the cylinder holes are provided. The members are constituted by common members.

With this configuration, the first and second cylinder holes having different numbers can be formed to have the same diameter, and different numbers of the first and second cylinder holes are formed in each cylinder hole.
By mounting the second tilt control piston and the first and second urging members, parts can be shared.

Further, in the invention of claim 4, the first tilt control piston is provided at a position for driving the swash plate to the small tilt side, and the second tilt control piston moves the swash plate to the large tilt side. Is provided at a position to be driven. Thus, the swash plate can be driven to the small tilt side by the first tilt control piston, and the swash plate can be driven to the large tilt side by the second tilt control piston.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case where a variable displacement type swash plate type hydraulic rotary machine according to an embodiment of the present invention is used as a variable displacement type swash plate type hydraulic pump according to FIGS. This will be described in detail. In the embodiment, the same components as those of the above-described conventional technology are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 31 denotes a swash plate employed in the present embodiment. The swash plate 31 has a smooth surface 31A, a shaft insertion hole 31B, and a pair of legs 31C, similarly to the swash plate 12 described in the prior art. 31
C and a convex curved surface 31D. As shown in FIG. 2, the swash plate 31 is formed integrally with piston contact portions 31E and 31F that project radially outward from the smooth surface 31A.

Here, the swash plate 31 is connected to the piston contact portion 31.
As shown in FIG. 2, the entire shape including E and 31F is formed so as to form a substantially cross shape along the XX line and the YY line passing through the center O of the rotating shaft 4, and the YY line is It constitutes an imaginary line connecting the top dead center position and the bottom dead center position of each piston 9. The swash plate 31 tilts along a plane orthogonal to the XX line and passing through the YY line. Matches.

Further, the smooth surface 31A of the swash plate 31 is
Is formed as an annular plane concentric with the center O of each of the above, and each shoe 10 slides and displaces on this smooth surface 31A so as to draw a ring-like locus. And the leg 3 of the swash plate 31
1C and 31C are disposed at left and right symmetrical positions with respect to the YY line, and extend in parallel with the YY line so as to cross the XX line.

Further, the piston contact portion 31 of the swash plate 31
E and 31F protrude radially outward with respect to the smooth surface 31A of the swash plate 31 along the YY line, and the surface side thereof has a smooth surface 3A.
It is a piston contact surface formed of a plane substantially parallel to 1A. The tilt control pistons 32B, 33B, which will be described later, always contact the piston contact portions 31E, 31F.
Reference numeral 1 denotes a tilting operation in the directions indicated by arrows A and B in FIG. 1 by the driving force from the tilt control pistons 32B and 33B.

Reference numerals 32 and 33 denote tilt actuators for tilting the swash plate 31, respectively.
Are first and second cylinder holes 32A, 3 formed as bottomed holes in the casing body 2 at positions corresponding to the Y-Y line so as to sandwich the cylinder block 5 from the radial outside.
3A and first and second tilt control pistons 32B, which are slidably inserted into the cylinder holes 32A and 33A, and whose spherical ends project from the cylinder holes 32A and 33A.
33B.

Here, the tilt control pistons 32B, 33B
Is disposed on the surface side of the swash plate 31 so as to sandwich the rotating shaft 4 (cylinder block 5) from the outside in the radial direction, and the spherical end thereof always contacts the surface side of the piston contact portions 31E and 31F. ing. And, these tilt control pistons 32
B and 33B are formed of the same piston member, and the first tilt control piston 32B is formed of a single piston member, whereas the second tilt control piston 33B is formed of a single piston member.
Is constituted by a pair (two) of piston members arranged so as to sandwich the YY line from both the left and right sides as shown in FIG.

Therefore, on the tilt actuator 33 side, a pair of cylinder holes 33A, 33A having the same hole diameter are formed as shown in FIG.
Each tilt control piston 33B is slidably provided in 3A. Also, as shown in FIG. 1 and FIG.
First and second control pressure chambers 32C and 33C are respectively formed between 2A and 33A and the tilt control pistons 32B and 33B. The control pressure chambers 32C and 33C supply and discharge tilt control pressures described later. The tilt control pistons 32B, 3
3B is moved back and forth from the cylinder holes 32A and 33A toward the piston contact portions 31E and 31F of the swash plate 31.

Further, in the control pressure chambers 32C and 33C,
Cylinder holes 32A, 33A and tilt control piston 3
2B and 33B, the first and the second members made of the same member.
Springs 32D and 33D as second urging members are provided, and the springs 32D and 33D constantly urge the tilt control pistons 32B and 33B in a direction to protrude from the cylinder holes 32A and 33A.

Then, a first piston member composed of a single piston member
The tilt control piston 32B of the swash plate 31 as shown in FIG.
At the same time as the first tilt control piston 14B described in the related art, the tilt control pressure is supplied into the control pressure chamber 32C through the branch pipe line 19 shown in FIG. Thereby, the swash plate 31 is tilted and driven in the direction of arrow B toward the small tilting side.

On the other hand, as shown in FIGS. 1 and 3, the second tilt control pistons 33B, 33B composed of two piston members always contact the piston contact portion 31F of the swash plate 31, and each control pressure is controlled. The total pressure receiving area for the chamber 33C is twice as large as that of the first tilt control piston 32B. For this reason, each of the second tilt control pistons 33B is
Generates a greater tilt driving force than the tilt control piston 32B, and tilts the swash plate 31 in accordance with the tilt control pressure supplied to and discharged from each control pressure chamber 33C through a control pipeline 34 described later. It is tilted and driven in the direction of arrow A to the side.

Further, reference numeral 34 denotes a control line adopted in the present embodiment. Although the control line 34 is constructed almost similarly to the control line 20 described in the prior art, the control line 3
Reference numeral 4 denotes a second control pressure chamber 33C, 33C of the tilt actuator 33, the distal end side of which is bifurcated as shown in FIGS.
It is connected to the.

The base end of the control line 34 is selectively connected to the control line 18 and the tank 17 via the capacity control valve 21, and the capacity control valve 21 is switched to the switching position (b). In some cases, the tilt control pressure from the pilot pump 16 is supplied to the control pressure chambers 33C through the control lines 18 and 34. Further, while the displacement control valve 21 is switched to the neutral position (a) or the switching position (c), the control line 34
Is connected to the tank 17, and the pressure in each of the control pressure chambers 33C decreases to the tank pressure level.

The variable displacement type swash plate type hydraulic pump according to the present embodiment has the above-described configuration, and its basic operation is not particularly different from that of the prior art.

However, according to the present embodiment, the swash plate 31
The tilting actuator 32 provided on one side in the radial direction of the cylinder block 5 in the tilting direction is a single cylinder hole 32A, a tilt control piston 32B, and a control pressure chamber 32C.
And the spring 32D, and the tilt actuator 33 provided on the other radial side of the cylinder block 5 includes two cylinder holes 33A, 33A, tilt control pistons 33B, 33B, and control pressure chambers 33C, 33C, respectively.
C and the springs 33D, 33D make it possible to form, for example, the tilt control pistons 32B, 33B, 33B and the springs 32D, 33D, 33D with the same members.

For this reason, the tilt actuators 32, 33
The tilt control pistons 32B and 33B, which are the components of (1), can be used as common components, and the springs 32D and 33D can also use common components, thereby reliably reducing the number of components. In addition, by reducing the number of parts, parts management and the like can be simplified, and workability during assembly can be improved.

When the displacement control valve 21 shown in FIG. 4 is switched from the neutral position (a) to the switching position (b), the tilt control pressure from the pilot pump 16 is applied to the control line 18,
Each control pressure chamber 33 of the tilt actuator 32 through 34
C can be supplied. In this case, the control pressure chamber 32C of the tilt actuator 33 is also connected to the pilot pump 16 through the branch line 19, and the same tilt control pressure is supplied to the control pressure chamber 32C.

However, the tilt control pistons 33B and 33B of the tilt actuator 33 have a total pressure receiving area for each control pressure chamber 33C twice as large as the tilt control piston 32B of the tilt actuator 32. Therefore, the tilt control pistons 33B, 33B can generate approximately twice the tilt driving force of the tilt control piston 32B, and while the displacement control valve 21 is switched to the switching position (B), each control pressure chamber 33C The swash plate 31 can be tilted and driven in the direction of the arrow A to the large tilt side in accordance with the tilt control pressure supplied and discharged into the inside.

When the displacement control valve 21 is switched to the switching position (C), the control line 34 is connected to the tank 17, and the pressure in each control pressure chamber 33C decreases to the tank pressure level. The tilt driving force of each tilt control piston 33B of the rotary actuator 33 is a spring 33.
The force is reduced to a minimum depending on the urging force of D. On the other hand, the tilt control piston 32B of the tilt actuator 32
Since the tilt control pressure from the pilot pump 16 is supplied into the control pressure chamber 32C through the branch pipe line 19, the tilt control pressure tilts the swash plate 31 in the small tilt direction in the direction of arrow B. It can be driven to roll.

Therefore, according to the present embodiment, the tilt control pistons 32B, 33B, which are the components of the tilt actuators 32, 33, can be formed by a common piston member, and the springs 32D, 33D have the same components. And the number of parts can be reliably reduced.
By reducing the number of parts, parts management and the like can be simplified, and workability during assembly can be improved.

Further, since the tilt control piston 33B of the tilt actuator 33 is constituted by two piston members, the degree of freedom in designing the layout of each tilt control piston 33B with respect to the casing 1 of the hydraulic pump is improved. Is increased, whereby the radial dimension of the casing 1 can be reduced, and the overall size of the apparatus can be reduced.

In the above-described embodiment, the first tilt control piston 32B is constituted by one piston member.
Although the case where the second tilt control piston 33B is configured by two piston members has been described as an example, the present invention is not limited to this. For example, the first tilt control piston is formed by two piston members. The second tilt control piston may be constituted by three or more piston members.

In the above embodiment, the swash plate 31 is tilted using two sets of tilt actuators 32 and 33 so as to sandwich the cylinder block 5 from the outside in the radial direction. However, the present invention is not limited to this. For example, as disclosed in Japanese Patent Application Laid-Open No. H8-200209, the present invention may be applied to a type in which a tilt actuator is provided in a casing at the back side of a swash plate.

Further, in the above-described embodiment, the case where the variable displacement type swash plate type hydraulic rotary machine is used as the hydraulic pump has been described as an example. However, the present invention is not limited to this. It can be widely applied to motors and the like.

[0064]

As described above in detail, according to the first aspect of the present invention, the first tilt control piston is provided at one radial position of the swash plate with respect to the rotary shaft. Since a plurality of second tilt control pistons are provided at the other radial position, for example, the first tilt control piston is formed by a second tilt control piston including a plurality of piston members. A larger tilting driving force can be generated, and the tilting drive of the swash plate can be performed stably. This makes it possible to share the components of the tilt actuator, thereby reducing the number of parts and improving workability during assembly.
The entire device can be formed compactly to reduce the size.

According to the second aspect of the present invention, the first
Since the second tilt control piston is formed of the same piston member, common parts can be used for the first and second tilt control pistons, and the workability during assembly can be improved, and the parts can be improved. Management and the like can be simplified.

On the other hand, according to the third aspect of the present invention, the first and second cylinder holes forming the tilt actuator are formed in different numbers from each other, and the first and second tilt holes provided in the respective cylinder holes are provided. Since the control piston and the first and second urging members are each formed of a common member, the first and second cylinder holes having different numbers can be formed to have the same hole diameter, and each cylinder hole has By mounting different numbers of the first and second tilt control pistons and the first and second urging members, it is possible to share components. Therefore, by using each component of the tilt actuator in common, the number of components can be reliably reduced, the workability at the time of assembling can be improved, and the entire device can be made compact to reduce its size. Can be.

In the invention described in claim 4, the first tilt control piston is provided at a position for driving the swash plate to the small tilt side, and the second tilt control piston tilts the swash plate to the large tilt. The swash plate can be driven to the small tilt side by the first tilt control piston, and the swash plate is stabilized to the large tilt side by the second tilt control piston. And can be driven.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a variable displacement swash plate type hydraulic pump according to an embodiment of the present invention.

FIG. 2 is an enlarged front view showing a swash plate in FIG. 1;

FIG. 3 is an enlarged cross-sectional view of a second tilt control piston, a piston contact portion of a swash plate, and the like, as viewed from a direction indicated by arrows III-III in FIG. 1;

FIG. 4 is a hydraulic circuit diagram showing a tilt actuator that tilts and drives a swash plate, a capacity control valve, and the like.

FIG. 5 is a longitudinal sectional view showing a variable displacement swash plate type hydraulic pump according to the related art.

FIG. 6 is a hydraulic circuit diagram showing a tilt actuator, a displacement control valve, and the like according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 4 Rotation shaft 5 Cylinder block 6 Cylinder 9 Piston 10 Shoe 31 Swash plate 31A Smooth surface 31E, 31F Piston contact part 32, 33 Tilt actuator 32A First cylinder hole 32B First tilt control piston 32C First Control pressure chamber 32D spring (first biasing member) 33A second cylinder hole 33B second tilt control piston 33C second control pressure chamber 33D spring (second biasing member)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shigetaka Nakamura 650, Kandamachi, Tsuchiura-shi, Ibaraki F-term in the Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. (Reference) 3H070 AA01 BB04 CC12 CC32 CC34 DD47 DD55 3H084 AA08 AA16 BB24 BB26 BB27 CC12 CC32 CC49

Claims (4)

[Claims] A casing, a rotating shaft rotatably provided in the casing, a cylinder block in which a plurality of cylinders are bored in an axial direction, and which rotates integrally with the rotating shaft in the casing; A plurality of pistons reciprocally inserted into each cylinder of the cylinder block, shoes mounted on the protruding end of each piston, and the front surface side serves as a smooth surface for slidably guiding each shoe. In a variable displacement type swash plate type hydraulic rotary machine including a swash plate having a back surface tiltably supported with respect to the casing and a tilt actuator for tilting and driving the swash plate, the tilt actuator includes: A first end of the swash plate that is displaceably provided on the casing at one radial position of the swash plate with respect to the rotation axis and that has a distal end contacting the swash plate.
Of the tilt control piston, and a plurality of the tilting directions of the swash plate are provided at the other radial position on the other side in the radial direction with respect to the rotation axis and displaceable in the casing, and a tip end of which is in contact with the swash plate. 2. A variable displacement swash plate type hydraulic rotary machine comprising: a tilt control piston according to claim 1. 2. The variable displacement swash plate type hydraulic rotary machine according to claim 1, wherein said first and second tilt control pistons are constituted by substantially the same piston members. 3. A casing, a rotating shaft rotatably provided in the casing, a cylinder block in which a plurality of cylinders are bored in an axial direction, and which rotates integrally with the rotating shaft in the casing. A plurality of pistons reciprocally inserted into each cylinder of the cylinder block, shoes mounted on the protruding end of each piston, and the front surface side serves as a smooth surface for slidably guiding each shoe. In a variable displacement type swash plate type hydraulic rotary machine including a swash plate having a back surface tiltably supported with respect to the casing and a tilt actuator for tilting and driving the swash plate, the tilt actuator includes: First and second cylinder holes provided at one side position and the other side position of the swash plate in the tilting direction with the rotating shaft interposed therebetween, and slidably inserted into the first and second cylinder holes. The first and the first The first and second tilt control pistons each having an end protruding from the cylinder hole abutting on the swash plate; and the first and second tilt control pistons and the first and second cylinder holes. First and second control pressure chambers formed between the first and second cylinders to advance and retreat the first and second tilt control pistons from the first and second cylinder holes by externally supplying and discharging the tilt control pressure. And first and second biasing members disposed in the first and second control pressure chambers and constantly biasing the first and second tilt control pistons toward the swash plate. The first and second cylinder holes are formed in different numbers from each other, and the first and second tilt control pistons and the first and second biasing members provided in the respective cylinder holes are common to each other. A variable displacement swash plate type hydraulic rotary machine characterized by comprising a member. 4. The first tilt control piston is provided at a position for driving the swash plate to the small tilt side, and the second tilt control piston is positioned for driving the swash plate to the large tilt side. 4. The variable capacity type swash plate type hydraulic rotary machine according to claim 1, wherein the variable capacity type swash plate type hydraulic rotary machine is configured to be provided on a rotary shaft.