JPH0988809A - Variable capacity swash plate type hydraulic rotary machine - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To stably hold a tilting driven swash plate at a maximum tilting position and a minimum tilting position, and to make the whole compact to achieve downsizing and weight reduction. To An oil passage 37 is formed in the casing 21 so that pressure oil for tilt control supplied to and discharged from a tilt control cylinder 34 is guided to a tilt support portion 30 of a swash plate 29. In addition, the tilt support portion 30 is provided with the recess 30A on the swash plate 29 side and the casing 2
It is composed of a concave portion 30B on the first side and a spherical ball 30C. An opening of the oil passage 37 is formed on the bottom side of the recess 30B on the casing 21 side, and relief means 38 for opening and closing the opening by the ball 30C is configured.

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 which is suitably used as a hydraulic pump, a hydraulic motor, etc. in a construction machine such as a hydraulic shovel.

[0002]

2. Description of the Related Art Generally, a swash plate is tilted by a tilt control cylinder so that the discharge capacity can be made variable in the case of a hydraulic pump and the rotation speed and torque can be made variable in the case of a hydraulic motor. The variable displacement type swash plate type hydraulic rotating machine is known, for example, from Japanese Patent Laid-Open No. 59-79078.

Therefore, as a variable displacement type swash plate type hydraulic rotating machine according to this type of conventional technology, a hydraulic motor will be described as an example with reference to FIGS.

In the drawing, reference numeral 1 denotes a casing, which is composed of a bottomed tubular casing body 1C having a tubular portion 1A and an annular front bottom portion 1B, and a rear casing 1D for closing the casing body 1C. Further, a rotary shaft insertion hole 1B1 for inserting a rotary shaft 2 described later is formed in a central portion of the front bottom portion 1B of the casing body 1C. The tilt control cylinder 1 which will be described later is located on the upper side of the front bottom portion 1B of the casing body 1C.
Cylinder hole 14A which constitutes a part of 4 is formed, and inner wall 1E of front bottom 1B serves as a contact surface with swash plate 9 described later.

Reference numeral 2 denotes a rotary shaft rotatably supported in a rotary shaft insertion hole 1B1 of the casing 1 through bearings 3 and 3, and the rotary shaft 2 is a rotary shaft insertion hole 1B of the front bottom portion 1B.
It projects to the outside through 1. Reference numeral 4 denotes a switching valve plate fixed to the rear casing 1D and having a supply / discharge port.

Reference numeral 5 denotes a cylinder block located in the casing 1 and splined so as to rotate integrally with the rotary shaft 2. The cylinder block 5 includes a plurality of (usually an odd number) cylinders 6 extending in the axial direction. (Only one is shown) is bored around the rotary shaft 2, and each cylinder 6 is formed with a cylinder port 6A that opens to the sliding surface 5A on one side of the cylinder block 5. The pistons 7, 7, ... Are slidably inserted into the respective cylinders 6, and the respective pistons 7 reciprocate in the respective cylinders 6 by the pressure oil supplied and discharged from the switching valve plate 4 side. It is like this.

While the cylinder block 5 makes one rotation, each piston 7 expands or contracts from each cylinder 6, and in the expansion stroke of the piston 7 corresponding to a half rotation of the cylinder block 5, it will be described later. Supply and discharge passage 15,
Each piston 7 presses the smooth surface 9A of the swash plate 9 via each shoe 8 by the pressure of the pressure oil supplied from the 16 side into each cylinder 6 as a pressing resultant force F described later. In the contraction stroke of the piston 7 corresponding to the remaining half rotation of the cylinder block 5, each piston 7 is pushed into each cylinder 6, and the pressure oil flowing into each cylinder 6 in the extension stroke is reached. Is discharged to the supply / discharge passages 15 and 16 side.

Reference numerals 8, 8, ... Show a plurality of shoes provided at the end of each piston 7, and each shoe 8 is configured to slide on a smooth surface 9A of a swash plate 9 described later.

Reference numeral 9 denotes a disc-shaped swash plate provided on the front bottom portion 1B side of the casing 1. The surface side of the swash plate 9 is a smooth surface 9A, and the rotary shaft 2 is inserted through the central portion thereof. A shaft insertion hole 9B is provided. Further, on the back surface side of the swash plate 9, as shown in FIGS. 6 to 9, the left side, which is located near the lower side of the rotary shaft insertion hole 9B and includes the spherical ball 10A, etc.,
Right tilt support parts 10 and 10 are provided, and a ridge line portion 11 linearly extending in the left-right direction is provided at the position of each tilt support part 10.
Are formed.

On the back surface side of the swash plate 9, there are formed a first seat surface 12 and a second seat surface 13 having different inclination angles with the ridge portion 11 as a boundary.
As shown in, the upper end on the seat surface 12 side is the thin-walled side end portion 9C, and the lower end on the seat surface 13 side is the thick-walled side end portion 9D.

As shown in FIG. 8, the swash plate 9 is in the maximum tilt position when the first seat surface 12 is in contact with the inner wall 1E of the casing 1. At this maximum tilt position, the pistons 7 of the respective pistons 7 are rotated. Since the stroke (reciprocating motion) becomes maximum and the flow rate of the pressure oil required for rotating the cylinder block 5 increases, the rotating shaft 2 rotates at a low speed with a large torque.

Further, as shown in FIG. 9, the second seat surface 13
Contact the inner side wall 1E of the casing 1, the swash plate 9 is at the minimum tilt position, and at this minimum tilt position, each piston 7
Since the stroke (reciprocation) is minimized and the flow rate of pressure oil required for the cylinder block 5 to rotate decreases,
The rotary shaft 2 rotates at high speed with a small torque.

Reference numeral 14 denotes a tilting control cylinder for tiltingly driving the swash plate 9. The tilting control cylinder 14 is located near the thin-side end 9C of the swash plate 9 and the inner wall 1 of the casing 1 is provided.
A bottomed cylindrical cylinder hole 14A formed in E, and a piston 1 as a movable part inserted into the cylinder hole 14A.
4B and. Then, the piston 14B of the tilt control cylinder 14 advances and retreats from the cylinder hole 14A in accordance with the pressure of the pressure oil supplied to and discharged from the cylinder hole 14A, and tilt-drives the swash plate 9.

Reference numerals 15 and 16 denote pressure oil supply / discharge passages formed in the rear casing 1D. The supply / discharge passages 15 and 16 are provided in the respective cylinders 6 of the cylinder block 5 via the supply / discharge ports of the switching valve plate 4. The pressure oil is supplied to and discharged from and the pistons 7 are operated.

Further, 17 is an oil passage formed in the cylindrical portion 1A of the casing main body 1C, etc. One end side of the oil passage 17 is connected to a displacement control valve (not shown) for tilt control, and the other end The side is connected to the cylinder hole 14A of the tilt control cylinder 14. The oil passage 17 supplies and discharges the pressure oil from the displacement control valve into the cylinder hole 14A of the tilt control cylinder 14 to drive the piston 14B.

In the variable displacement type swash plate type hydraulic motor configured as described above, the pressure oil is supplied from the high pressure side passage of the supply / discharge passages 15 and 16 shown in FIG. As a result, each piston 7 extends (projects) from the cylinder 6 toward the swash plate 9 side, and the pressing resultant force F at this time acts on the smooth surface 9A of the swash plate 9, so that the lateral component of this pressing force F. The shoe 8 is a smooth surface 9A of the swash plate 9
Along the circumference in the circumferential direction, the pistons 7 and the cylinder block 5 rotate integrally therewith, and the rotary shaft 2
Rotates and operates as a hydraulic motor.

The oil passage 17 is provided by the capacity control valve.
The pressure of the pressure oil supplied to the tilt control cylinder 14 is variably controlled via the
By advancing and retracting B from the cylinder hole 14A, the swash plate 9 tilts between the maximum tilting position shown in FIG. 8 and the minimum tilting position shown in FIG.

In this case, the pressing force F exerted by each piston 7 acts on the substantially central position of the swash plate 9, and the tilt support portion 10 is positioned lower than this by the dimension b (b '). Therefore, if the pressure of the pressure oil supplied to the tilt control cylinder 14 is reduced and the tilting force f by the tilt control cylinder 14 is reduced, the seat surface 12 of the swash plate 9 contacts the inner wall 1E of the casing 1. Stable in contact.

On the other hand, in order to drive the swash plate 9 from the maximum tilt position shown in FIG. 8 toward the minimum tilt position shown in FIG. 9,
The tilting force f (pressure of the pressure oil) of the tilting control cylinder 14 is increased, and tilting applied to the swash plate 9 at a position of a distance a from the tilting support portion 10 to the point of action of the tilting force f. The moment (f × a) is calculated as the pressing moment (F × F) of the pressing resultant force F.
By making it smaller than b),

[0020]

If the relational expression f × a> F × b is satisfied, the swash plate 9 can be tilted from the maximum tilt position (FIG. 8) to the minimum tilt position (FIG. 9). .

Then, in the state where the swash plate 9 is tilted to the minimum tilt position as shown in FIG. 9, the distance x from the thick side end 9D of the swash plate 9 to the tilt support portion 10 is defined as this thickness. Meat side end 9
The relationship between the tilting moment [f × (a + x)] and the pressing moment [F × (b + x)] with D as the fulcrum,

[0022]

By setting F × (b + x)> f × (a + x), the swash plate 9 is excessively tilted in the direction of the arrow M in FIG. 9 with the thick-side end 9D as the fulcrum. Therefore, the swash plate 9 can be stably held at the minimum tilting position with the seat surface 13 in contact with the inner wall 1E of the casing 1.

[0023]

By the way, in the above-mentioned prior art, in order to stably hold the swash plate 9 at the minimum tilting position shown in FIG. 9, it is necessary to satisfy the equations (1) and (2). The distance a is increased as compared with the distance b, and the distance (b + x) from the point of action of the pressing resultant force F to the thick side end portion 9D of the swash plate 9 is increased to increase the outer diameter dimension of the swash plate 9. There is a problem that the swash plate 9 cannot be made compact and compact because it needs to be large.

That is, in order to satisfy the equation (1), it is necessary to make the distance a larger than the distance b, and to satisfy the equation (2), it is necessary to increase the distance (b + x). Therefore, the outer diameter of the swash plate 9 inevitably becomes large, and the entire casing 1 becomes large, which makes it difficult to form the entire apparatus compactly.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention provides a swash plate tilt-driven between a maximum tilt position and a minimum tilt position, for example, a minimum tilt dislocation maximum. It is an object of the present invention to provide a variable displacement type swash plate type hydraulic rotating machine which can be stably held and can be made compact and can be made compact and lightweight.

[0026]

In order to solve the above-mentioned problems, the present invention provides a casing, a cylinder block rotatably provided in the casing and having a plurality of cylinders bored in the axial direction, A plurality of pistons that are reciprocally inserted into each cylinder of the cylinder block, shoes attached to the ends of the pistons, one side is a smooth surface that guides each shoe, and the other side is inclined to the casing. The swash plate tiltably provided via the rolling support portion and the casing for tilt-driving the swash plate, the movable portion is provided by supplying and discharging pressure oil for tilt control. The present invention is applied to a variable displacement swash plate type hydraulic rotating machine including a tilt control cylinder that advances and retreats toward the other side surface of the swash plate.

The features of the configuration adopted by the present invention are as follows.
In the casing, an oil passage for guiding pressure oil for tilt control supplied to and discharged from the tilt control cylinder to the tilt support portion of the swash plate is formed, and in the tilt support portion of the swash plate, The tip end side of the oil passage is always closed, and when the pressure oil in the oil passage reaches an excessive pressure, the tip end side of the oil passage is opened to provide relief means for letting the pressure oil escape into the casing. It is in.

Further, in the invention according to claim 2, between the other side of the swash plate and the inner side wall of the casing, a first angle is formed which is different from the angle of the tilt support part. First and second seat surfaces are provided, the first seat surface holding the swash plate in a surface contact state at the maximum tilt position, and the second seat surface having the swash plate at the minimum tilt position. It is configured to be kept in contact.

Further, in the invention according to claim 3, the tilting support portion of the swash plate has a spherical convex portion provided on the other side surface of the swash plate, and the casing of the casing corresponding to the convex portion. The convex portion is formed on the inner wall, and the convex portion is configured with a spherical concave portion that slidably engages with the bottom surface side of the concave portion. The relief means is constructed by releasably providing the opening so as to be opened and closed in the recess.

[0030]

According to the first aspect of the invention, the casing is provided with an oil passage for guiding the tilt control pressure oil supplied to and discharged from the tilt control cylinder to the tilt support portion of the swash plate. By providing relief means in the tilt support portion, the tip end side of the oil passage is normally closed, and when the pressure oil in the oil passage becomes an excessive pressure, the tip end side of the oil passage is opened and placed in the casing. Since the pressure oil is released, when the pressure of the pressure oil supplied to the tilt control cylinder is increased to drive the swash plate by the tilt control cylinder to, for example, the minimum tilt position, the pressure oil is Even if the pressure of the swash plate becomes excessively large, the relief means opens the front end side of the oil passage, and the pressure oil at this time can be released into the casing, and the swash plate further tilts beyond the minimum tilt position. It can be reliably prevented from being overturned.

In this case, as in the second aspect of the invention, between the other side of the swash plate and the inner side wall of the casing are formed at different angles with respect to the position of the tilt support portion. First and second seat surfaces are provided, and the first seat surface holds the swash plate in a surface contact state at a maximum tilt position,
The second seat surface is configured to hold the swash plate in a surface contact state at the minimum tilt position, so that the swash plate can be stably held at the maximum tilt position and the minimum tilt position.

Further, as in the invention according to claim 3, the tilt support portion of the swash plate has a spherical convex portion provided on the other side surface of the swash plate, and the casing of the casing corresponding to the convex portion. The convex part is formed on the inner wall, and the convex part slidably engages with the spherical concave part, so that the convex part slides (swings) in the concave part on the casing side to maximize the swash plate. It is possible to smoothly tilt between the tilted position and the minimum tilted position.

The relief means for opening and closing the opening can be constituted by the convex portion by providing an opening portion on the bottom side of the concave portion for opening the tip side of the oil passage. The opening can be surely closed by pressing the convex portion of the swash plate into the concave portion on the casing side by the pressure (pressing force). On the other hand, when the pressure oil (pressure) for tilt control becomes excessive pressure, if the tip end side of the convex portion is separated from the opening portion of the concave portion even slightly, the opening portion can be automatically opened, The pressure oil for tilt control can be released into the casing to reduce the pressure of the pressure oil.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION A variable displacement type swash plate type hydraulic rotating machine according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 4 as an example. 2 in the figure
Reference numeral 1 denotes a casing of the hydraulic motor. The casing 21 has a bottomed cylindrical casing body 21C having an open end 21A on one end side and an annular front bottom portion 21B on the other end side, and an open end of the casing body 21C. A rear casing 21D for closing the 21A side is formed, and a rotary shaft insertion hole 21B1 for inserting a rotary shaft 22 described later is formed in a central portion of a front bottom portion 21B of the casing body 21C.

Further, a cylinder hole 34A, which is located on the upper side thereof and constitutes a part of a tilt control cylinder 34, which will be described later, is formed in the front bottom portion 21B of the casing body 21C, and the inner wall of the front bottom portion 21B is formed. First, which will be described later
The second sheet surfaces 31 and 32 are formed.

Reference numeral 22 denotes a rotary shaft insertion hole 21 of the casing 21.
B1 indicates a rotary shaft rotatably supported by bearings 23A and 23B. The rotary shaft 22 has its tip end inserted through a rotary shaft insertion hole 21B1 of the front bottom portion 21B. Reference numeral 24 denotes a switching valve plate fixed to the rear casing 21D and having a supply / discharge port.

Reference numeral 25 denotes a cylinder block located in the casing 21 and spline-coupled so as to rotate integrally with the rotary shaft 22, and the cylinder block 25 has a plurality of (usually an odd number) cylinders 26 extending in the axial direction. , 26,
(Only one is shown) is formed around the rotary shaft 22, and each cylinder 26 is formed with a cylinder port 26A that opens to the sliding surface 25A on one side of the cylinder block 25.

The pistons 27, 27, ... Are slidably inserted into the respective cylinders 26, and the respective pistons 2 are
Numeral 7 is adapted to reciprocate in each cylinder 26 by the pressure oil supplied and discharged from the switching valve plate 24 side.

Here, while the cylinder block 25 makes one rotation, each piston 27 expands or contracts from each cylinder 26, and in the expansion stroke of the piston 27 corresponding to a half rotation of the cylinder block 25, it will be described later. Each piston 27 presses the smooth surface 29A of the swash plate 29 through each shoe 28 with the force of the pressing resultant force F by the pressure of the pressure oil supplied from the supply / discharge passages 35, 36 side into the cylinder 26. Further, in the compression stroke of the piston 27 corresponding to the remaining half rotation of the cylinder block 25, each piston 27 is pushed into each cylinder 26, and the pressure oil that has flowed into each cylinder 26 in the extension stroke is reached. Will be discharged to the supply / discharge passage side.

Reference numerals 28, 28, ... Show a plurality of shoes swingably provided at the end of each piston 27, and each shoe 28 slides on a smooth surface 29A of a swash plate 29 described later. Has become.

Reference numeral 29 denotes a front bottom portion 21 of the casing 21.
A disc-shaped swash plate provided on the B side is shown. The swash plate 29 has a smooth surface 29A on the front surface side, and a rotary shaft insertion hole 29B through which the rotary shaft 22 is inserted is bored in the central portion. . Also,
The back surface side of the swash plate 29 is formed as a flat contact surface 29C, and the contact surface 29C is the seat surface 3 on the casing 21 side.
1, 32 are selectively brought into contact with each other.
The swash plate 29 has the smooth surface 29A formed with a constant inclination angle, so that the upper end side of the swash plate 29 is formed as the thin side end 29D and the lower end side is formed as the thick side end 29E. There is.

Reference numerals 30 and 30 denote tilt support portions for tiltably supporting the swash plate 29 on the front bottom portion 21B of the casing 21, and each tilt support portion 30 is thicker than the point of application of the pressing resultant force F. The spherical recess 30A, which is located closer to the meat side end 29E and is recessed in the contact surface 29C of the swash plate 29, and the front bottom portion 2 of the casing 21, which is located on the ridge line portion 33 described later.
1B, spherical concave portions 30B, and the concave portions 30
A and 30B each have a spherical ball 30C slidably engaged with the ball 30C.
A convex portion for B is formed.

Here, the front bottom portion 2 of the casing 21
In 1B, a first seat surface 31 and a second seat surface 32 are provided on the inner side wall facing the contact surface 29C of the swash plate 29,
Inclined at a constant angle with respect to the second seat surface 32,
When the contact surface 29C of the swash plate 29 comes into contact with the swash plate 29 as shown in FIG. 2, the swash plate 29 is held at the maximum tilt position in a surface contact state.

Further, as shown in FIG. 4, between the seat surfaces 31 and 32, there is a linear ridge line portion 33 which crosses each recess 30B of the tilt support portion 30 in the left-right direction, and the position of the ridge line portion 33 is used as a boundary. The seat surfaces 31 and 32 are set at different angles. The contact surface 29C of the swash plate 29 is shown in FIG.
As shown in, when the second seat surface 32 is contacted, the swash plate 2
9 is the minimum tilt position and is held in a surface contact state. At this minimum tilt position, the stroke (reciprocating motion) of each piston 27 is minimized, and the rotary shaft 22 rotates at a high speed with a small torque.

Reference numeral 34 indicates a tilt control cylinder for tilting the swash plate 29. The tilt control cylinder 34 is a swash plate 2
9. A bottomed cylindrical cylinder hole 34 formed on the seat surface 31 side of the casing 21 and located closer to the thin side end 29D of the casing 9.
A and a piston 34B as a movable part slidably fitted in the cylinder hole 34A. The piston 34B of the tilt control cylinder 34 advances and retreats from the cylinder hole 34A in accordance with the pressure of the pressure oil supplied to and discharged from the cylinder hole 34A, and tilts the swash plate 29.

Reference numeral 35 denotes an oil passage formed in the casing body 21C or the like. One end of the oil passage 35 is connected to a displacement control valve 36 for tilt control, and the other end is a cylinder hole of the tilt control cylinder 34. 34A. And
The oil passage 35 supplies and discharges the pressure oil from the displacement control valve 36 into the cylinder hole 34A of the tilt control cylinder 34, and drives the piston 34B.

Reference numerals 37 and 37 denote a pair of oil passages formed on the front bottom portion 21B side of the casing main body 21C. The respective oil passages 37 are symmetrical left and right around the rotary shaft insertion hole 21B1 as shown in FIG. And is formed as a bow-shaped passage of about 1/4 turn. One end of each oil passage 37 communicates with the cylinder hole 34A of the tilt control cylinder 34, and the other end extends toward the recess 30B of each tilt support portion 30. An opening 37A of each oil passage 37 is formed.

Here, each opening 37A is closed by each ball 30C mounted in the recess 30B as shown in FIGS. 2 and 3, and each ball 30C is normally in each oil passage 37 (cylinder hole 34A). It prevents the pressure oil inside the bracket from leaking out. Each ball 30C is connected to each oil passage 3
When the pressure oil in 7 becomes excessive pressure as described later, the relief means 38 is formed so as to open each opening 37A slightly apart from the concave portion 30B. At this time, the pressure oil in each oil passage 37 is The recesses 30B are discharged (relieved) into the casing body 21C.

Further, 39 and 40 are rear casings 21.
A supply / discharge passage for pressure oil formed in D is shown.
Reference numerals 9 and 40 are for supplying / discharging pressure oil to / from the cylinder block 25 through the supply / discharge ports of the switching valve plate 24 and operating each piston 27.

The variable displacement type swash plate hydraulic motor according to the present embodiment has the above-mentioned structure, and the basic operation of the hydraulic motor is not different from that of the conventional art.

However, in this embodiment, the oil passages 37 for guiding the pressure oil for tilt control supplied to and discharged from the tilt control cylinder 34 to the tilt support portions 30 of the swash plate 29 are connected to the front of the casing 21. The concave portion 3 of each tilt support portion 30 is formed on the bottom portion 21B side.
Since the oil passages 37 that open into the 0B can be opened and closed by the balls 30C of the tilt support portions 30, the relief means 38 are configured by the balls 30C.
The following effects can be obtained.

That is, the front bottom portion 21 of the casing 21.
B is formed at different tilt angles at the respective tilt support portions 30, and the contact surface 29C of the swash plate 29 is selectively selected when the swash plate 29 is tilted to the maximum and minimum tilt positions. Since the first and second seat surfaces 31, 32 that contact the swash plate 29 are provided on the inner side wall of the front bottom portion 21B, the swash plate 29 contacts the first seat surface 31 at the maximum tilt position of the swash plate 29, for example. The surface 29C can be contacted in a surface contact state, and the swash plate 29 can be stably held at the maximum tilt position.

When the swash plate 29 is tilted from the maximum tilt position to the minimum tilt position, pressure oil is supplied into the cylinder hole 34A of the tilt control cylinder 34 through the oil passage 35. By pushing the thin side end portion 29D of the swash plate 29 with the piston 34B, the swash plate 29 can be tilted in the direction of the arrow M in FIG. 3, and the contact surface 29C of the swash plate 29 at the minimum tilt position. By abutting against the second seat surface 32, the swash plate 29 can be stably held at the minimum tilt position.

Then, in a normal state in which pressure oil is supplied to and discharged from each cylinder 26 of the cylinder block 25 and the hydraulic motor is rotationally driven, the pressing resultant force F from each piston 27 acts on the swash plate 29, Since the balls 30C of the tilt support portion 30 are pressed into the recesses 30B by this pressing resultant force F, the openings 30A of the oil passages 37 can be kept closed by the balls 30C of the relief means 38, and the oils of the oil passages 37 can be kept closed. It is possible to prevent the pressure oil in the passage 37 from leaking into the casing body 21C.

On the other hand, when the swash plate 29 is tilt-driven by the tilt control cylinder 34 to the minimum tilt position shown in FIG.
If the tilting moment in the direction becomes excessive, the swash plate 29 may be tilted further in the direction of the arrow M from the position shown in FIG. 3 with the thick side end 29E as the fulcrum.

However, if the swash plate 29 tilts slightly from the position shown in FIG. 3 in the direction of the arrow M, a gap will be formed between the ball 30C and the recess 30B of each tilt support 30. , The opening 37A of each oil passage 37 has a ball 30C.
The pressure oil in each oil passage 37 can be discharged so as to be relieved by the casing body 21C,
Excessive pressure oil can be released from the cylinder hole 34A of the tilt control cylinder 34 into the casing body 21C via the oil passages 37.

Therefore, according to the present embodiment, even if an excessive tilting moment shown by the arrow M direction in FIG. 3 acts on the swash plate 29, the excessive pressure (pressure oil) at this time causes each oil Road 37
The swash plate 29 can be held in the minimum tilting position shown in FIG. 3 by being relieved in the casing body 21C via the swash plate 29, and the swash plate 29 can be further tilted in the direction of the arrow M. In addition to being automatically prevented, the swash plate 29 can be stably tilted between the minimum tilt position and the maximum tilt position (see FIG. 2), and the tilt motion of the swash plate 29 is stabilized for a long time. be able to.

Further, by stabilizing the tilting motion of the swash plate 29, it is not necessary to make the outer diameter dimension of the swash plate 29 large as described in the prior art, and the whole structure is made compact and the hydraulic pressure is reduced. It is possible to reduce the size and weight of the motor.

Furthermore, each tilt support portion 30 of the swash plate 29 is
The first and second seat surfaces 31, 3 on the casing 21 side
2 and the contact surface 29C of the swash plate 29 are provided with spherical recesses 30A and 30B, and spherical balls 30C slidably engaged with the recesses 30A and 30B, respectively. The ball 30C can be smoothly slid (swing) in the recessed portion 30B on the casing 21 side.
9 can be stably tilted between the maximum tilt position and the minimum tilt position.

In the embodiment, the first and second seat surfaces 31, 32 for holding the swash plate 29 at the maximum tilt position and the minimum tilt position are provided on the inner wall of the front bottom portion 21B of the casing 21. However, the present invention is not limited to this, and, for example, like the swash plate 9 described in the related art,
The first and second sheet surfaces may be formed on the other surface side of the swash plate. Further, contact surfaces having different angles are formed on both the other side surface of the swash plate and the inner wall of the casing with the tilt support portion as a boundary, and the contact surfaces make the first and second contact surfaces.
You may comprise a 2nd sheet | seat surface.

Further, in the above-mentioned embodiment, a hydraulic motor was described as an example of the variable displacement type swash plate type hydraulic rotating machine, but the present invention is not limited to this, and may be applied to, for example, a variable displacement swash plate type hydraulic pump. Widely applicable.

[0062]

As described above in detail, according to the first aspect of the invention, the oil passage for guiding the pressure oil for tilt control supplied to and discharged from the tilt control cylinder to the tilt support portion of the swash plate. Is formed in the casing, and the tilting support portion of the swash plate is provided with relief means, so that the tip end side of the oil passage is always closed, and when the pressure oil in the oil passage becomes excessive pressure, the oil passage Since the pressure oil is supplied to the tilt control cylinder by increasing the pressure oil supplied to the tilt control cylinder, the tilt control cylinder tilts the swash plate to, for example, the minimum tilt position. Even when the pressure of the pressure oil becomes excessively high during the rolling drive, the pressure oil at this time can be released into the casing by opening the tip side of the oil passage by the relief means. Can be reliably prevented from being further tilted beyond the minimum tilt position. Therefore, the swash plate can be stably tilted between the maximum tilt position and the minimum tilt position, and the swash plate can be reduced in size and weight, and the entire structure can be made compact.

In this case, as in the second aspect of the present invention, it is formed between the other side of the swash plate and the inner side wall of the casing at different angles with the position of the tilt support portion as a boundary. By providing the first and second seat surfaces, the swash plate can be stably held in the surface contact state at the maximum tilt position on the first seat surface, and the swash plate can be minimized on the second seat surface. The tilted position can be stably held in a surface contact state.

According to the third aspect of the present invention, the tilting support portion of the swash plate is a spherical convex portion provided on the other side surface of the swash plate, and the casing is provided corresponding to the convex portion. Since the convex portion is formed on the inner wall of the casing, and the convex portion is configured to have a spherical concave portion that slidably engages with the concave portion, the convex portion can be smoothly slid (swing) in the concave portion on the casing side, and can be slanted. The plate can be stably tilted between the maximum tilt position and the minimum tilt position. The relief means for opening and closing the opening can be configured by the convex portion by providing an opening portion on the bottom surface side of the concave portion that opens on the tip side of the oil passage, and pressure oil for tilt control (pressure ) Becomes excessive pressure, the pressure oil for tilt control can be released into the casing by opening the opening in the concave portion on the tip side of the convex portion, and the swash plate becomes excessive. It is possible to reliably prevent tilting.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a variable displacement swash plate type hydraulic motor according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of essential parts showing a swash plate, a tilt support portion, and the like in a maximum tilt position.

FIG. 3 is a view showing a state where the swash plate is tilted to a minimum tilt position.
FIG. 4 is a vertical cross-sectional view of a substantial part similar to FIG.

4 is a cross-sectional view taken along the line IV-IV in FIG. 1 showing an enlarged front bottom side of the casing with a swash plate, a rotary shaft and the like removed.

FIG. 5 is a longitudinal cross-sectional view of a main part showing a variable displacement swash plate type hydraulic motor according to a conventional technique.

6 is a rear view of the swash plate shown in FIG.

FIG. 7 is a left side view of the swash plate shown in FIG.

FIG. 8 is an explanatory diagram showing a maximum tilt position of a swash plate.

FIG. 9 is an explanatory diagram showing a minimum tilt position of a swash plate.

[Explanation of symbols]

 21 Casing 22 Rotational Shaft 25 Cylinder Block 26 Cylinder 27 Piston 28 Shoe 29 Swash Plate 30 Tilt Support 30A, 30B Recess 30C Ball 31 First Seat Surface 32 Second Seat Surface 34 Tilt Control Cylinder 34A Cylinder Hole 34B Piston (Movable part) 37 Oil passage 37A Opening 38 Relief means

Claims (3)

[Claims] 1. A casing, a cylinder block that is rotatably provided in the casing and has a plurality of cylinders bored in the axial direction, and a plurality of cylinder blocks that are reciprocally inserted into each cylinder of the cylinder block. A piston, a shoe attached to the end of each piston, and a swash plate on one side that is a smooth surface that guides each shoe and the other side is tiltably provided on the casing via a tilt support portion. A tilt control cylinder that is provided in the casing to tilt drive the swash plate and that moves and moves the movable portion toward the other side surface of the swash plate by supplying and discharging pressure oil for tilt control. In the variable displacement swash plate type hydraulic rotating machine, an oil passage is formed in the casing for guiding pressure oil for tilt control supplied to and discharged from the tilt control cylinder to a tilt support portion of the swash plate. , The tilt support portion of the swash plate is The front end side of the passage is normally closed, and when the pressure oil in the oil passage becomes excessive pressure, the front end side of the oil passage is opened to provide relief means for releasing the pressure oil into the casing. Variable capacity swash plate type hydraulic rotary machine. 2. The first and second seat surfaces are formed between the other side of the swash plate and the inner wall of the casing at different angles with respect to the position of the tilt support portion. The first seat surface holds the swash plate in a surface contact state at the maximum tilt position, and the second seat surface holds the swash plate in a surface contact state at the minimum tilt position. Item 1. A variable capacity swash plate type hydraulic rotating machine according to Item 1. 3. The tilt supporting portion of the swash plate is formed on the inner side wall of the casing corresponding to the spherical convex portion provided on the other side surface of the swash plate and the convex portion. Is formed with a spherical recess that slidably engages with the bottom of the recess, and an opening for opening the tip of the oil passage is provided on the bottom side of the recess so that the projection opens and closes the opening. 3. The relief means is configured by being removably provided in the concave portion in the recess.
Variable capacity swash plate type hydraulic rotating machine described in.