JPH06147096A - Swash plate type hydraulic pump-motor - Google Patents

Abstract

PURPOSE:To tiltingly roll a swash plate accurately between two tiltingly rolling positions by controlling the extent of wear in a pressing piston and a cylinder hole so effectively. CONSTITUTION:When a center shaft S of a pressing piston 82 is tilted as far as an angle 5 B being less than a specified angle A to a straight line L, the center shaft S of the pressing piston 82 is approximated to a perpendicular line to a second flat part 57 at the time of a swash plate 51 being tilted, so that a crossed angle between these elements becomes lessened, and thereby a vertical component force, pressing the pressing piston 82 to an inner circumference of a cylinder hole 80 becomes lessened, whereby wear is effectively controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swash plate type fluid pump / motor in which a stroke of a plunger is changed by tilting a swash plate between two tilting positions.

[0002]

2. Description of the Related Art As a conventional swash plate type fluid motor, for example, one described in Japanese Utility Model Publication No. 4-29430 is known. In this structure, a swash plate located in the casing is pressed from the back side by a pressing means to tilt the swash plate between two tilting positions, so that the plunger in the cylinder block slidingly contacting the inclined surface of the swash plate is In the swash plate type fluid motor whose stroke is changed, the pressing means is
A cylinder hole formed in the casing, a pressing piston slidably inserted in the cylinder hole, and a high-pressure fluid is introduced into the cylinder hole to press the tip of the pressing piston against a flat portion on the back surface of the swash plate. The swash plate is arranged such that the flat portion is tilted from one tilt position where the flat portion is located on a plane perpendicular to the rotation axis of the cylinder block to the side where the flat portion is separated from the pressing piston by a predetermined angle with respect to the vertical plane. And a fluid passage for tilting to a tilting position, and the central axes of the cylinder hole and the pressing piston are parallel to the rotation axis of the cylinder block.

[0003]

However, in such a conventional swash plate type fluid motor, as described above, the central axes of the cylinder hole and the pressing piston are parallel to the rotation axis of the cylinder block. When the swash plate is tilted away from one tilt position to the other tilt position side, the central axis of the pressing piston and the straight line perpendicular to the flat portion on the back surface of the swash plate intersect. Therefore, the pressing force (acting in the direction perpendicular to the flat portion on the back surface of the swash plate) M applied from the plunger to the pressing piston via the swash plate is parallel to the central axis of the pressing piston as shown in the upper side of FIG. A component force (a force that moves the pressing piston in the cylinder hole in the axial direction) N, and a component force perpendicular to the central axis of the pressing piston (a force that presses the pressing piston to the inner circumference of the cylinder hole) Q. Is decomposed into. Here, this vertical component force Q increases as the flat portion on the back surface of the swash plate moves away from the vertical plane, and its value is the intersection angle D between the straight line perpendicular to the flat portion and the central axis of the pressing piston.
Is given by M sinD. The swash plate tilts from one tilted position to the other tilted position or from the other tilted position to one tilted position each time the plunger stroke is changed. At the time of rolling, the pressing piston moves axially in the cylinder hole while being pressed against the inner circumference of the cylinder hole by the above-mentioned vertical component force Q, so that the outer circumference of the pressing piston and the inner circumference of the cylinder hole are repeatedly tilted. Rolling causes gradual wear, and as a result, high-pressure fluid guided to the cylinder holes may leak between them and stop before the swash plate reaches the other tilt position. There is.

The present invention provides a swash plate type fluid pump / motor capable of effectively suppressing wear of a pressing piston and a cylinder hole and accurately tilting a swash plate between one and the other tilt positions. The purpose is to provide.

[0005]

The object is to press the swash plate located in the casing from the back side by the pressing means to tilt the swash plate between two tilting positions. In a swash plate type fluid pump / motor adapted to change the stroke of a plunger in a cylinder block slidingly contacting an inclined surface, the pressing means is slidably inserted into a cylinder hole formed in a casing and the cylinder hole. The pressing piston and the tip of the pressing piston are pressed against a flat portion on the rear surface of the swash plate by introducing high-pressure fluid into the cylinder hole, and the flat portion is placed on a plane P substantially perpendicular to the rotation axis of the cylinder block. The fluid passage for tilting from one tilting position F located at the other side to the other tilting position G where the flat part is tilted to the plane P by a predetermined angle A away from the pressing piston. And the central axis S of the cylinder hole and the pressing piston with respect to the straight line L parallel to the rotation axis of the cylinder block toward the rear end of the pressing piston by an angle B less than the predetermined angle A. It can be achieved by sloping away from L in the radial direction.

[0006]

Now, it is assumed that the high-pressure fluid is guided to the cylinder hole through the fluid passage, and the pressing piston is moving in the cylinder hole toward the tip end side by the high-pressure fluid. At this time, since the tip of the pressing piston is pressed against the flat portion on the back surface of the swash plate, the swash plate is pushed by the pressing piston and tilts from one tilt position to the other tilt position. is there. Even while the swash plate is being tilted, a pressing force M is applied from the plunger to the pressing piston via the swash plate as shown in the lower side of FIG. 3. The action direction of this pressing force is the back surface of the swash plate. Since it is perpendicular to the flat portion, the pressing force M is parallel to the central axis S of the pressing piston when the extending direction of the central axis of the pressing piston and the straight line perpendicular to the flat portion intersect. A component force (which is a force that moves the pressing piston in the cylinder hole in the axial direction) N and a component force that is perpendicular to the central axis S of the pressing piston (which is a force that presses the pressing piston to the inner circumference of the cylinder hole) Q The vertical component force Q becomes a force that abrades the outer circumference of the pressing piston and the inner circumference of the cylinder hole. For this reason, in the present invention, the straight line L is moved toward the rear end of the piston by the angle B less than the predetermined angle A with respect to the straight line L parallel to the rotation axis of the cylinder block with respect to the central axis S of the cylinder hole and the pressing piston. It is inclined so as to be separated radially outward from. As described above, when the central axis S of the cylinder hole and the pressing piston is inclined by the angle B as described above, the central axis S of the pressing piston is
Approaches the vertical line to the flat part when the swash plate is in the intermediate position between the one tilt position and the other tilt position, which causes the vertical line to the flat part being tilted and the pressing piston to move. The absolute value of the intersection angle J with the central axis S is always smaller than before (it is zero when the swash plate is tilted by an angle B from one tilt position), and the vertical component force Q given by M sinJ is always Get smaller. For this reason, even if the swash plate is tilted from one tilt position to the other tilt position or from the other tilt position to one tilt position each time the stroke of the plunger is changed. Since the pressing piston is only pressed against the inner circumference of the cylinder hole by the small vertical component force Q described above during movement, the pressing piston is hardly worn by the repeated tilting of the swash plate from the outer circumference of the pressing piston and the inner circumference of the cylinder hole. As a result, the high-pressure fluid guided to the cylinder hole does not leak from between them, and the swash plate can accurately reach the other tilted position.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 21 is, for example, a swash plate type fluid motor for driving a crawler vehicle. The fluid motor 21 has a case main body 22, and the other end surface of the case main body 22 has a cylindrical storage chamber extending toward one side. 23 are formed.
A side plate 24 is fixed to the other end of the case body 22,
As a result, the storage chamber 23 is closed and sealed by the side plate 24. 28 is a rotary shaft having the other side portion inserted into the storage chamber 23, and the rotary shaft 28 includes a pair of bearings 29,
It is rotatably supported by the side plate 24 and the case body 22 via 30. Then, one end of the rotary shaft 28 is attached to the case main body 22.
And is connected to a sprocket that engages with a crawler (not shown). Reference numeral 31 denotes a ring-shaped plate fixed to the bottom surface of the storage chamber 23, that is, one end surface, and the other end surface 32 of the plate 31 is a plane substantially perpendicular to the rotation shaft 28 and a rotation axis K of a cylinder block 38 described later. It is a flat surface located on P. The case main body 22, the side plate 24, and the plate 31 described above as a whole include the fluid motor 21.
The casing 33 of is configured.

Reference numeral 38 denotes a cylindrical cylinder block housed in the housing chamber 23. The other end of the rotary shaft 28 is inserted into the cylinder block 38 and spline-connected to the cylinder block 38. The rotary shaft 28 is connected to the rotary shaft 28 so as to rotate integrally therewith. This cylinder block 38
A plurality of cylinder holes 39 extending in the axial direction are formed in one end surface of the cylinder holes 39, and these cylinder holes 39 are arranged equidistantly in the circumferential direction. Within these cylinder holes 39 are cylinder holes 39
And the same number of plungers 40 are slidably inserted,
A spherical sphere portion 41 is formed at the tip of each plunger 40, that is, at one end. 42 is a cylinder block fixed to the side plate 24
The timing plate 42 is a timing plate located between the side plate 24 and the side plate 24. Two long arc-shaped holes 43 are formed in the timing plate 42 in the circumferential direction, and the cylinder holes 39 are formed in the arc-shaped holes 43. 38 turns to connect one after another. Reference numerals 44 and 45 denote supply / discharge passages formed in the side plate 24. The supply / discharge passage 44 is always in communication with one arc-shaped hole 43, and the supply / discharge passage 45 is always in communication with the other arc-shaped hole 43. Also, these supply and discharge passage
44 and 45 are connected to a pump and a tank via a switching valve (not shown), and when the switching valve is switched, one of them becomes a supply side and the other becomes a discharge side.

1 and 2, 51 is housed in a housing chamber 23 of a casing 33, and one end surface of a cylinder block 38 and one inner surface of the casing 33, more specifically, the other end surface 32 of a plate 31.
It is a substantially ring-shaped swash plate located between and.
The rotary shaft 28 penetrates the inside. The inclined surface (the other end surface) 52 of the swash plate 51 facing the cylinder block 38 is a rotary shaft 28.
Of the swash plate 51. As a result, the swash plate 51 can be divided into a thick portion 53 and a thin portion 54 with the central portion as a boundary. In addition, the other end surface 32 of the plate 31
The rear surface (one end surface on the opposite side of the inclined surface 52) 55 of the swash plate 51 facing the first flat portion 56 located substantially on the thick portion 53 side and substantially parallel to the plane perpendicular to the rotation axis K of the rotation shaft 28. And this first
It is composed of two flat portions, that is, a second flat portion 57 that is inclined at a small predetermined angle A with respect to the flat portion 56 and is located on the thin portion 54 side, and the boundary between these first and second flat portions 56, 57 is It is separated from the center of the swash plate 51 toward the thick portion 53 by a predetermined distance.

Reference numeral 58 denotes two fulcrum members supported by the casing 33, and a straight line (tilt line) connecting these fulcrum members 58.
Is the tilt center line of the swash plate 51. Where each fulcrum member
58 has a hemispherical fulcrum main body 59 in which an insertion hole 60 is formed at the center of a flat bottom surface, and one side of a fulcrum shaft 62 having a cylindrical shape is loosely fitted in each of the insertion holes 60. On the other hand, two hemispherical recesses 63 are formed on the back surface 55 of the swash plate 51 on the boundary between the first and second flat portions 56 and 57.
Are arranged at a predetermined distance in the extending direction of the boundary. The fulcrum main bodies 59 are inserted into the recesses 63 in a state of spherical contact, and at this time, the bottom surfaces of the fulcrum main bodies 59 are in surface contact with the other end surface 32 of the plate 31. Further, columnar fixing holes 64 are formed in the other end surface 32 of the plate 31 (a facing surface facing the back surface 55 of the swash plate 51) at a position facing the recesses 63, and these fixing holes 64 have the above-mentioned fixing holes 64. The other side of the fulcrum shaft 61 is inserted and fixed. The fulcrum body 59 and the fulcrum shaft 61 described above are the fulcrum member as a whole.
58, and the swash plate 51 includes these two fulcrum members 5
8, more specifically, the first tilt position F (which is one tilt position where the second flat portion 57 is located on the plane P with the straight line connecting the centers of curvature of the fulcrum body 59 (the tilt straight line) as the center. Figure 2
The second flat 57 and the plate as shown by the solid line in
The other end surface 32 of 31 is in surface contact), and the second tilted position as the other tilted position in which the second flat portion 57 is tilted toward the side separated from the plate 31 by a predetermined angle A from the plane P. G
It is possible to tilt between (the first flat portion 56 and the other end surface 32 of the plate 31 are in surface contact with each other as shown in phantom in FIG. 2).

70 is the same number of shoes as the plunger 40,
Each shoe 70 has a ball hole in which the ball 41 of the plunger 40 is stored.
71 is formed. The ball portion 41 and the ball hole 71 described above collectively constitute a ball joint joint 72, whereby one end of the plunger 40 and the shoe 70 are connected via the ball joint joint 72. The shoes 70 are formed on the inclined surface 52 of the swash plate 51.
Slidably engaged with. A retainer plate 73 is a ring-shaped retainer plate loosely fitted to the outside of the rotary shaft 28. The retainer plate 73 is arranged between the cylinder block 38 and the swash plate 51 and engages with all the shoes 70. ing.
74 is a thrust ball arranged between the cylinder block 38 and the retainer plate 73.
The outer surface of 74 on the side close to the retainer plate 73 is formed of a part of a spherical surface. And this thrust ball
The outer surface of 74 makes spherical contact with the inner circumference of the retainer plate 73, and the thrust ball 74 is fitted to the outside of the rotary shaft 28 and connected by spline coupling. A spring 75 is interposed between the cylinder block 38 and the thrust ball 74.
The shoe 70 is pressed against the inclined surface 52 to prevent the shoe 70 from rising from the inclined surface 52.

A cylinder hole 80 is formed in the casing 33 facing the second flat portion 57 of the swash plate 51, specifically in the case body 22 and the plate 31, and a pressing piston 82 slides in the cylinder hole 80. It is inserted as possible. Here, the center axis S of the cylinder hole 80 and the pressing piston 82 is the rear end of the pressing piston 82 (swash plate) by an angle B less than the predetermined angle A with respect to a straight line L parallel to the rotation axis K of the cylinder block 38. It is inclined so as to be separated from the straight line L toward the outer side in the radial direction as it goes toward one end) separated from 51. A ball hole 83 is formed at the tip of the pressing piston 82, and a ball portion 85 formed at one end of the shoe 84 is inserted into the ball hole 83. As a result, the shoe 84 and the pressing piston 82 are
They are connected via a ball joint joint 86 composed of 83 and a ball portion 85. Further, a spring 87 for biasing the shoe 84 toward the swash plate 51 is interposed between the pressing piston 82 and the bottom surface of the cylinder hole 80, whereby the other end surface of the shoe 84 has a thin wall of the swash plate 51. It is pressed against the back surface 55 (second flat portion 57) of the portion 54. Reference numeral 88 is a fluid passage formed in the casing 33. One end of the fluid passage 88 is connected to a fluid source (not shown), and the other end is connected to the cylinder hole 80. Then, the high-pressure fluid passes through the fluid passage 88 and the cylinder hole 80
When the pressure piston 82 is supplied to the
Since the swash plate 51 moves toward the swash plate 51 while being in contact with the second flat portion 57 of the swash plate 51, the swash plate 51 moves from the first tilt position F to the second tilt position about the tilt straight line. When the tilting straight line is offset to the thick portion 53 side from the center of the swash plate 51 when tilted to G and the supply of the high pressure fluid to the cylinder hole 80 is stopped, the tilting straight line is offset by the pressing force from the plunger 40. The swash plate 51 tilts from the second tilt position G to the first tilt position F. As a result, the stroke of the plunger 40 in the cylinder block 38 is changed in two steps, and the rotational speeds of the cylinder block 38 and the rotary shaft 28 are changed in two steps. The cylinder hole 80, the pressing piston 82, the shoe 84, the spring 87, and the fluid passage 88 described above as a whole are swash plates located inside the casing 33.
A pressing means 89 for pressing the 51 from the back surface 55 side is configured.

Next, the operation of the embodiment of the present invention will be described. When the high-pressure fluid is supplied from the supply / discharge passage 44 to the cylinder hole 39 of the cylinder block 38 through the one arc-shaped hole 43, the plunger 40 in the cylinder hole 39 projects toward the swash plate 51 and presses the inclined surface 52. , At this time, the plunger
Since the tip of 40 is engaged with the inclined surface 52 via the shoe 70, the component force of the pressing force acts on the plunger 40, whereby the plunger 40 and the shoe 70 move on the inclined surface 52 on the thick portion. 53
Slide from the side toward the thin portion 54 side,
40, the cylinder block 38, and the rotary shaft 28 integrally rotate about the rotary axis K. The rotation of the cylinder block 38 causes the cylinder hole 39 communicating with the other arc-shaped hole 43.
The inner plunger 40 moves from the thin portion 54 side toward the thick portion 53 side while engaging with the inclined surface 52 of the swash plate 51 via the shoe 70, so that the inclined surface 52 causes the plunger 40 to move into the cylinder hole 39. The fluid is gradually pushed in and the fluid in the cylinder hole 39 is pushed out and discharged through the other arc-shaped hole 43 and the supply / discharge passage 45. At this time,
Since the shoe 70 is pressed against the inclined surface 52 of the swash plate 51 by the urging force of the spring 75 transmitted via the thrust ball 74 and the retainer plate 73, even if the fluid in the cylinder hole 39 is discharged, the shoe 70 The 70 does not rise above the slope 52.

Here, for example, when the crawler vehicle is climbing a slope, the fluid motor 21 must rotate at a low speed with a large torque. In this case, the supply of the high pressure fluid to the cylinder hole 80 through the fluid passage 88 is stopped, and the swash plate 51 is not pressed by the pressing piston 82. Here, as described above, the tilting straight line is offset from the center of the swash plate 51 to the thick portion 53 side, so that the swash plate 51 tilts to the first tilting position F by the pressing force from the plunger 40. ing. At this time, the stroke of the plunger 40 in the cylinder block 38 becomes longer, but the amount of high-pressure fluid flowing into the fluid motor 21 is constant, so the rotation speed of the cylinder block 38 and the rotation shaft 28 becomes low.

Next, when the crawler vehicle starts to run steadily on level ground, for example, the fluid motor 21 must be rotated at a high speed with a small torque. In this case, a high-pressure fluid is supplied to the cylinder hole 80 through the fluid passage 88, and the pressing piston 82 moves toward the swash plate 51 while contacting the second flat portion 57 of the swash plate 51 via the shoe 84. Let As a result, the swash plate 51 is pushed by the pressing piston 82 and tilts from the first tilting position F to the second tilting position G about the tilting straight line. This allows the plunger 40 in the cylinder block 38 to
Stroke becomes shorter, cylinder block 38, rotary shaft
28 will rotate at high speed. Here, when tilting as described above, the pushing piston is pushed from the plunger 40 through the swash plate 51.
As shown in FIG. 3, a pressing force M is applied to 82. Since the acting direction of this pressing force is perpendicular to the second flat portion 57 of the back surface 55 of the swash plate 51, the center of the pressing piston 82 is When the extending direction of the axis S and the straight line perpendicular to the second flat portion 57 intersect, the pressing force M is a component force parallel to the central axis S of the pressing piston 82 (the pressing piston 82 is Decomposed into a component force perpendicular to the central axis S of the pressure piston 82 (which is a force that pushes the pressure piston 82 against the inner circumference of the cylinder hole 80) N and a force N that causes the force to move in the hole 80 in the axial direction. The vertical component force Q may cause frictional contact between the outer circumference of the pressing piston 82 and the inner circumference of the cylinder hole 80 to cause wear. However, in this embodiment, as described above, the central axis S of the cylinder hole 80 and the pressing piston 82 is less than the predetermined angle A with respect to the straight line L parallel to the rotation axis K of the cylinder block 38.
And the central axis S of the pressing piston 82 is brought close to the vertical line with respect to the second flat portion 57 when the swash plate 51 is at the intermediate position between the first tilt position F and the second tilt position G. I made it. As a result, the absolute value of the intersection angle J between the vertical line with respect to the second flat portion 57 during tilting and the central axis S of the pressing piston is always smaller than before (the swash plate 51 moves from the first tilting position F to the angle B).
When it is tilted only, it becomes zero), and the vertical component force Q given by M sinJ is always small. From this, the swash plate 51 is changed to the first one every time the stroke of the plunger 40 is changed.
Even when the tilting position F is tilted to the second tilting position G or tilted from the second tilting position G to the first tilting position F, the pressing piston 82 is moved by the small vertical component force Q described above during the movement. Since it is only pressed against the inner circumference of the hole 80, the swash plate 51 does not mean the outer circumference of the pressing piston 82 and the inner circumference of the cylinder hole 80.
Almost no wear is caused by repeated tilting. As a result, the high-pressure fluid guided to the cylinder hole 80 does not leak from between them, and the swash plate 51 can accurately reach the second tilt position G.

In the above embodiment, the fulcrum body
59 and the fulcrum shaft 62 are separate bodies, but in the present invention, they may be integrated, or the hemispherical shape may be a semi-cylindrical shape.
In this case, the concave portion into which this semi-cylindrical portion is inserted is also semi-cylindrical. Further, in the present invention, the casing
The recess formed in 33 may be hemispherical or semi-cylindrical, and the recess formed in the swash plate 51 may be cylindrical. Further, in the above embodiment, the back surface 55 of the swash plate 51 is composed of two flat portions 56 and 57 intersecting at a predetermined angle A, and the facing surface (the other end surface 32) of the casing 33 facing the back surface 55 is formed. Although it is composed of one flat surface, in the present invention, the back surface 55 of the swash plate 51 is composed of one flat surface, and the opposing surface of the casing 33 is composed of two flat portions intersecting at a predetermined angle A. You may Further, in the present invention, a third tilting position may be provided near the middle of the first and second tilting positions F and G, and the swash plate 51 may be tilted between the three tilting positions. . In this case, set the stroke of the plunger 40 to 3
Can be changed in stages. Further, although the present invention is applied to the fluid motor 21 in the above-described embodiments, the present invention may be applied to a fluid pump.

[0017]

As described above, according to the present invention, since the wear of the pressing piston and the cylinder hole can be effectively suppressed, the swash plate can be accurately positioned between the one tilt position and the other tilt position. Can be tilted.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention.

FIG. 2 is a front sectional view in the vicinity of a swash plate.

FIG. 3 is an explanatory diagram illustrating an operation.

[Explanation of symbols]

 21 ... Swash plate type fluid motor 33 ... Casing 38 ... Cylinder block 40 ... Plunger 51 ... Swash plate 52 ... Inclined surface 55 ... Rear surface 57 ... Flat part 80 ... Cylinder hole 82 ... Pressing piston 88 ... Fluid passage 89 ... Pressing means F, G ... Tilt position K ... Rotation axis P ... Plane A ... Predetermined angle S ... Central axis L ... Straight line B ... Angle

Claims (1)

[Claims] 1. A swash plate 51 located in a casing 33 is provided with a rear surface 55.
The swash plate type in which the stroke of the plunger 40 in the cylinder block 38 slidingly contacting the inclined surface 52 of the swash plate is changed by pressing by the pressing means 89 from the side and tilting between the two tilt positions. In the fluid pump / motor 21,
The pressing means is a cylinder hole 80 formed in the casing.
A pressing piston 82 slidably inserted in the cylinder hole, and a high-pressure fluid is introduced into the cylinder hole to press the tip of the pressing piston against a flat portion 57 on the back surface of the swash plate to flatten the swash plate. From one tilt position F where the portion is located on a plane P that is substantially perpendicular to the rotation axis K of the cylinder block, to the other side where the flat portion is inclined from the pressing piston by a predetermined angle A with respect to the plane P. And a fluid passage 88 for tilting to a tilting position G, and an angle B smaller than the predetermined angle A with respect to a straight line L parallel to the rotation axis of the cylinder block and the central axis S of the cylinder hole and the pressing piston. The straight line L as it goes toward the rear end of the pressing piston
The swash plate type fluid pump / motor is characterized in that it is inclined so as to be separated radially outward from the.