JP2577326B2 - Driving device for cam mechanism and axial piston - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an input point moving straight line and an output point moving orthogonal to an input point and an output point by contacting a cam provided on a first member and a cam follower provided on a second member. The present invention relates to a cam mechanism that moves along a straight line, and an axial piston driving device to which the cam mechanism is applied.

[0002]

2. Description of the Related Art A swash plate is pivotally supported on an input shaft which is slidable in the axial direction, and a cam follower provided on the swash plate is brought into contact with a cam. A hydraulically driven diaphragm pump that changes the angle of the plate has already been proposed by the present applicant (see Japanese Patent Publication No. 1-38198).

[0003]

By the way, when a predetermined point on the swash plate is not displaced in the axial direction from the state of the swing angle of 0 ° when the swash plate is swung, the swash plate is not moved at the predetermined point. Is held at the top dead center or the bottom dead center. However, in the above-described conventional type, when the swing angle of the swash plate is changed, the axial piston at the top dead center or the bottom dead center is also displaced in the axial direction, so that the position of the top dead center or the bottom dead center is shifted. There is a problem. For example, assuming that the position of the top dead center changes, the tip of the axial piston may collide with the end wall of the axial cylinder at the top dead center, so the clearance at the tip of the axial piston needs to be set large. Therefore, there is a problem that dead clearance occurs and pump efficiency is reduced. Therefore, when the input shaft is slid in the axial direction, the above-mentioned problem is solved if the predetermined point on the swash plate does not move along the axis, but moves on an axis perpendicular to the axis.

The present invention has been made in view of the above-mentioned circumstances, and provides a cam mechanism in which an input point and an output point move on axes orthogonal to each other, and an axial piston driving apparatus to which the cam mechanism is applied. The purpose is to provide.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, a cam provided on a first member and a cam follower provided on a second member are brought into contact with each other. A cam mechanism for moving an input point and an output point provided on a member along an input point movement straight line and an output point movement straight line, respectively, which are orthogonal to each other. The cams are formed along the plane, and the cam followers are respectively positioned at a pair of vertexes at diagonal positions of the square arranged on the plane, and the input point and the output point are respectively set at the other pair of vertexes of the square. It is characterized by being located.

According to a second aspect of the present invention, there is provided an axial piston driving device using the cam mechanism according to the first aspect, wherein the axial piston driving device is disposed on the input point moving straight line in a direction of the input point moving straight line. A slidable rotary shaft, a cam member arranged to surround the outer periphery of the rotary shaft, immovable in the direction of the input point moving straight line, and rotatable with the rotary shaft; A cam provided along a first straight line and a second straight line, a pivot fixed to a rotating shaft so as to be orthogonal to the input point moving straight line, and a pivot axis constituting the input point; A swash plate pivotally supported by a pivot, a cam follower provided on the swash plate, an axial cylinder disposed on the outer periphery of a rotating shaft in parallel with the input point moving straight line, and an axial cylinder. Sliding on To fit, characterized in that a axial piston which is slidably coupled to the swash plate via the output point.

[0007]

According to the first aspect of the present invention, when the input point of the second member moves along the input point movement straight line, the cam follower of the second member is guided along the cam of the first member, so that the second member is guided. The output points of the two members move along an output point movement straight line orthogonal to the input point movement straight line.

According to the second aspect of the present invention, when the rotating shaft is slid along the input point movement straight line, the cam follower of the swash plate pivotally supported by the rotating shaft via the pivot contacts the cam of the cam member. Causes the swash plate to swing. At this time, since the output point moves along the output point movement straight line orthogonal to the input point movement straight line by the movement of the input point along the input point movement straight line, the axial piston connected to the swash plate at the output point moves upward. The position of the dead center or the bottom dead center is kept constant.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show one embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a hydrostatic continuously variable transmission, and FIG.
3 is a sectional view taken along line 2-2 of FIG. 1, FIG. 3 is a sectional view taken along line 3-3 of FIG.
Is an explanatory view of the operation, and FIG. 5 is an explanatory view of the principle of the cam mechanism.

As shown in FIGS. 1 to 3, the hydrostatic continuously variable transmission T includes a front housing 1, a center housing 2 and a rear housing 3 which are divided into three parts in an axial direction and are connected to each other. The axial piston pump P is housed in a space defined by the front housing 1 and the central housing 2, and the rear housing 3 and the central housing 2
The radial piston motor M is housed in the space defined by.

An axial piston pump P includes a ball bearing 4 provided on a front housing 1 and a central housing 2.
And an input shaft 6 (rotary shaft of the present invention) supported by a roller bearing 5 provided in the first embodiment. The input shaft 6 is rotated and is connected to a drive source (not shown), slides along the axis L _A by and not shown gear mechanism. A cylindrical portion 8 of a cam member 7 (first member of the present invention) is fitted on the outer periphery of the input shaft 6, and its axial front end face is positioned by the ball bearing 4, and its axial rear end face is It is positioned by a thrust bearing 9 that is disposed between the roller bearing 5 and receives a thrust load.

[0013] A pin 1 planted so as to penetrate the input shaft 6.
0 (the pivot of the present invention) is the axis L on the cylindrical portion 8 of the cam member 7._A
Slot 8 formed in the direction₁, 8₁Penetrate through. Cam member 7
Annular swash plate 11 (second member of the present invention) that is loosely fitted on the outer periphery of
Pin hole 11 formed in the inner surface of ₁, 11₁To both pins 10
The ends are fitted, and the swash plate 11 swings back and forth around the pin 10.
It is movable. At this time, the swing angle of the swash plate 11 should be controlled.
In addition, the cam member 7 has a cam 12 at the front end and a cam 12 at the rear end.
_F, 12_RAre formed on the front side and the rear side of the swash plate 11.
Of the cam 12_F, 12_REach
Mfolowa 13 _F, 13_RSliding contact.

Therefore, the input shaft 6 is connected to the axis L_ASliding in the direction
Swash plate 1 connected to input shaft 6 via pin 10
1 also axis L_AThe cam member 7 moves in the axial direction.
Since it cannot move, the cam 12 of the cam member 7_F, 12_R
Cam Follower 13_F, 13 _RSwash plate 11 slides
(See FIG. 4).

The rear housing 3 and the central housing 2 support five cylinder members 14 spaced apart at intervals of 72 ° in the circumferential direction so as to be rotatable around their own axis. Each cylinder member 14 has an axial cylinder 15 extending in the axial L _A direction is formed, axial piston 16 respectively to the axial cylinder 15 is fitted slidably. A ball joint 17 is swingably connected to the front end of the axial piston 16. The ball joint 17 is connected to a clip 1 provided on the outer periphery of the swash plate 11.
8 locked. Then, the sliding surface 17 ₁ of the sliding surface 19 ₁ and the ball joint 17 of the ball bearing 19 which is supported on the flange 11 ₂ formed on the outer periphery of the swash plate 11 abuts slidably.

[0016] The axial piston 16 and the oil hole 16 ₁ of the L-shape is drilled, with its one end of the oil hole 16 ₁ communicates with the front oil chamber 20 formed inside the front housing 1, and the other end of the oil hole 16 ₁ communicates with the interior of the axial cylinder 15. Inside the oil hole 16 ₁ of the axial piston 16, and allows the flow of hydraulic fluid to the radial piston motor M side from the axial piston pump P side,
A check valve 21 that regulates the flow of hydraulic oil from the radial piston motor M to the axial piston pump P is provided.

A radial piston motor M housed in a rear oil chamber 22 defined by the rear housing 3 and the central housing 2 has an output shaft 2 arranged coaxially with the input shaft 6.
3 is provided. An intermediate portion of the output shaft 23 is supported through a ball bearing 24 to the rear housing 3, also the front end portion is supported fitted relatively rotatably in the shaft hole 6 ₁ formed on the rear end of the input shaft 6.

A radial cylinder 25 communicating with the axial cylinder 15 is formed in each cylinder member 14 in a radial direction, and a radial piston 26 is slidably fitted to the radial cylinder 25. The outer periphery of the output shaft 23, the eccentric cam surface 27 having a distance e by an eccentric axis L _A 'with respect to the axis L _A are formed, the radially inner end of the radial piston 26 to the eccentric cam surface 27 Abuts.

[0019] oil groove 27 ₁ formed over the eccentric cam surface 27 to 180 °, the oil hole 26 ₁ through the interior of the radial piston 26 in the axial direction can be communicated. The communicating portion between the radial cylinder 25 and the axial cylinder 15 has
A check valve 28 is provided to allow the flow of hydraulic oil from the axial piston pump P to the radial piston motor M and to restrict the flow of hydraulic oil from the radial piston motor M to the axial piston pump P.

The space between the front housing 1 and the input shaft 6 is sealed by a seal member 29, and the rear housing 3 and the output shaft 2 are sealed.
The three spaces are sealed by a seal member 30. The hydraulic oil is filled in the front oil chamber 20 and the rear oil chamber 22 communicate with each other by the communication holes 2 ₁ ... formed in the middle housing 2.

As described above, the common cylinder member 14
Since the axial cylinder 15 and the radial cylinder 25 are formed in an L-shape so as to communicate with each other, not only the number of parts is reduced as compared to the case where the cylinders are formed in separate members, but also the two cylinders are connected. It is also possible to omit the oil passage which is used, and a great simplification of the structure is achieved.

As is apparent from FIG. 1, the cam member 7 has a shape.
A pair of cams 12 formed before and after_F, 12 _RIs the axis L_AAgainst
Each at an angle of 45 ° and at an angle of 90 ° to each other.
doing. The illustrated state in which the inclination angle of the swash plate 11 is 0 °.
The axis L passing through the center of the pin 10_AOrthogonal to
Axis L_RIs the sliding surface 17 of the ball joint 17 ₁
And sliding surface 19 of ball bearing 19₁Pass through.
Thus, the cam 12_FCam follower 13 that abuts_FRank
Position is point A, and cam 12_RCam follower 13 that abuts
_RPosition is point B, the center of pin 10 is point C,
Face 17₁And sliding surface 19₁Let the upper predetermined position be point D
And these points A to D are respectively located at the four vertices of the square.
Corresponding.

In the first aspect of the invention, the point C constitutes an input point of the cam mechanism, and the point D constitutes an output point of the cam mechanism. The axis L _A constitutes an input point movement straight line, and the axis L _R constitutes an output point movement straight line. Further, the cam 12 _F constitutes a first straight line, the cam 12 _R
Constitutes a second straight line.

[0024] sliding the input shaft 6 along the axis L _A, the cam 12 _F, 12 _R and the cam follower 13 _F, 13 _R
The swash plate 11 by the sliding contact with the is swung to the pin 10 about (i.e. point C around), D points at that time is moved along the axis L _R, does not move in the axial L _A direction. Hereinafter, the reason will be described with reference to FIG.

In FIG. 5, the X and Y axes of the XY coordinates are shown.
Is cam 12_F, 12_RRespectively, and one side of
Point A of square ACBD with length a (Cam follower 1
3_F) Is the X axis (cam 12_F), And slide point B
Mfolowa 13_F) Is the Y axis (cam 12_RSliding along)
I do. At this time, the square is compared from the initial position indicated by the chain line.
Considering the case of rotation by θ in the counterclockwise direction,
(Input point) coordinates C (X _C, Y_C) And D point (output point)
Coordinates D (X_D, Y_D) Is X_C= A sinθ ... (1) Y_C= −a sin θ (2) X_D= A cosθ ... (3) Y_D= A cos θ (4)

When a and θ are eliminated from the expressions (1) and (2), Y _C = −X _C (5) is obtained. When a and θ are eliminated from the expressions (3) and (4), , Y _D = X _D (6) is obtained.

Equation (5) indicates that the point C (input point) is a straight line Y = -X
(That is, moving on the axis L _A ).
Equation (6) indicates that point D (output point) is a straight line Y = X (ie, axis L
_R ) indicates that you are moving on. And Thus, by moving the point C (input point) along the axis L _A, if and A point (cam follower 13 _F) and point B (the cam follower 13 _R) is slid along the cam 12 _F, 12 _R , D point (output point)
Move along the axis L _R.

Next, the operation of the embodiment of the present invention having the above-described configuration will be described.

In FIG. 1, when the input shaft 6 is driven to rotate,
The cam member 7 and the swash plate 11 connected to the input shaft 6 via the pin 10 rotate. At this time, the swing angle of the swash plate 11 is 0 °.
Therefore, the axial piston 16 does not make a stroke, and the discharge oil amount of the axial piston pump P becomes zero. As a result, the radial piston motor M is not driven, and the output shaft 23 is stopped.

In this state, when the input shaft 6 is slid in the direction of the arrow, for example, as shown in FIG. 4, a pin 10 integral with the input shaft 6 is formed into a long hole 8 ₁ formed in the cylindrical portion 8 of the cam member 7. , 8
By moving along _one, the swash plate 11 moves relative to the cam member 7. As a result, the pair of cam followers 13 _F and 13 _R formed before and after the swash plate 11 is
Are guided by the cams 12 _F and 12 _R formed before and after the swash plate 11, and the swash plate 11 swings counterclockwise around the pin 10.

As described above, when the swash plate 11 rotates together with the input shaft 6 and the cam member 7 in the inclined state, the five axial pistons 16 connected to the swash plate 11 via the ball bearings 19 and the ball joints 17. … But 72
Reciprocating drive is performed sequentially with a stroke S with a phase difference of °. When the axial pistons 16 move rightward in the figure, the check valves 28 are closed and the check valves 21 are opened, so that hydraulic oil in the front oil chamber 20 is filled with oil holes in the axial pistons 16. 16 ₁ ... through sucked into axial cylinder 15 ... inside. When the axial pistons 16 move leftward in the figure, the check valve 21
Are closed and the check valves 28 are opened,
The hydraulic oil in the axial cylinders 15 is discharged into the radial cylinders 25.

The hydraulic oil discharged into the radial cylinders 25 presses the outer end faces of the radial pistons 26 radially inward, and the inner end faces of the radial pistons 26
By pressing the eccentric cam surface 27 provided in 3, the output shaft 23 is driven to rotate. The stroke of the radially inner radial piston 26 ... is completed, to 26 ₁ ... communicating two oil holes oil groove 27 ₁ is a radial piston 26 ... of which is formed on the eccentric cam surface 27 as shown in FIG. 3, the radial piston The hydraulic oil in the radial cylinders 25 is discharged to the rear oil chamber 22 with the radially outward stroke of the hydraulic cylinders 26. The hydraulic oil in the rear oil chamber 22 flows back to the front oil chamber 20 through the communicating hole 2 ₁ ... formed in the middle housing 2.

[0033] In Thus, by adjusting the sliding amount along the axis L _A of the input shaft 6, since the amount of oil discharged axial piston pump P is changed oscillation angle of the swash plate 11 is changed,
The rotation speed of the output shaft 23 with respect to the rotation speed of the input shaft 6 continuously changes, so that the continuously variable transmission between the input shaft 6 and the output shaft 23 is achieved.

The clearance δ (see FIG. 1) between the tip of the axial pistons 16 and the check valves 28 is set to be larger than that in the embodiment, and the axial pistons 16 are further moved leftward from the position shown in FIG. If possible, the rotation direction of the output shaft 23 with respect to the rotation direction of the input shaft 6 can be changed by reversing the suction and discharge phases of the axial piston pump P by sliding the input shaft 6 in the opposite direction to that described above. Can be inverted.

When the angle of the swash plate 11 is adjusted by sliding the input shaft 6 in the direction of the axis L _A , the output point D does not move in the direction of the axis L _{A but in the} direction of the axis L _R as described above. Move only to. That is, even if the stroke S of the axial pistons 16 is changed by adjusting the swing angle of the swash plate 11, the position of the top dead center of the axial pistons 16 is always kept constant. Thus, the axial piston 16
Since the position of the top dead center does not change, the clearance δ between the tip of the axial piston 16 and the check valve 28.
Can be set to a minimum to improve pump efficiency. When the output point D of the swash plate 11 moves along the axis L _R , the sliding surface 19 ₁ of the ball bearing 19 slides on the sliding surface 17 ₁ of the ball joints 17. movement is absorbed along the axis L _R of the output point D.

Although the embodiments of the present invention have been described in detail above, various design changes can be made in the present invention without departing from the gist thereof.

For example, the cam mechanism of the present invention is not limited to the swash plate drive of an axial piston pump or an axial piston motor, but can be applied to any other applications. The present invention is also applicable to a diaphragm pump that drives a diaphragm with an axial piston. In this case, by keeping the position of the bottom dead center of the axial piston, that is, the position where the volume of the working chamber defined by the diaphragm is maximum, it is possible to keep the amount of oil sucked into the working chamber constant. Becomes

[0038]

As described above, according to the first aspect of the present invention, when the input point of the second member is moved along the input point movement straight line, the cam follower of the second member becomes the first member. By being guided along the cam, the output point of the second member moves along the output point movement straight line orthogonal to the input point movement straight line. Thereby, the input point and the output point of the second member can be moved along the mutually orthogonal straight lines.

According to the second aspect of the present invention,
Even if the rotation axis is slid along the input point movement straight line to change the angle of the swash plate, the output point on the swash plate moves along the output point movement straight line orthogonal to the input point movement straight line. The position of the top dead center or the bottom dead center of the axial piston connected to the swash plate at the output point can be kept constant.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a hydrostatic continuously variable transmission.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;

FIG. 4 is an explanatory diagram of an operation.

FIG. 5 is a diagram illustrating the principle of a cam mechanism.

[Explanation of symbols]

6 Input shaft (rotary shaft) 7 Cam member (first member) 10 Pin (axis) 11 Swash plate (second member) 12 _F cam 12 _R cam 13 _L cam follower 13 _R cam follower 15 Axial cylinder 16 Axial piston C Input point D output point L _A axis (input point linear movement) L _R axis (output point linear movement)

Claims (2)

(57) [Claims] 1. A cam ( _12F , 12F) provided on a first member (7).
12 _R ) and the cam follower (1) provided on the second member (11).
The 3 _F, 13 abut with _R), the input point linear movement (L _A) and the output point moves straight line perpendicular input point provided on the second member (11) (C) and an output point (D) with each other (L _R ), wherein the cams (12 _F , 12 _R ) are formed along a first straight line and a second straight line that are orthogonal to each other on a plane, and are formed on the plane. the cam follower pair of vertices in the diagonal positions of the arranged squares (13 _F, 13 _R) and causes the position respectively, the input point to the other pair of vertices of the square (C) and an output point (D) A cam mechanism characterized by being respectively positioned. 2. A drive device of the axial piston using a cam mechanism of claim 1, sliding in the direction of the input point linear movement (L _A) is placed on to said input force point moves linearly (L _A) moving freely rotating shaft (6), is disposed so as to surround the outer periphery of the rotary shaft (6) rotates, it is immovable in the direction of the input point linear movement (L _a), and the rotary shaft together with (6) and possible be cam member (7), the input to the first straight line and the cam provided along the second straight line (12 _F, 12 _R) to the cam member (7), the rotary shaft (6) _A pivot (1) fixed to be orthogonal to the point movement straight line (LA) and constituting the input point (C).
0), a swash plate (11) arranged to surround the outer periphery of the cam member (7), and pivotably supported by a pivot (10); and the cam follower provided on the swash plate (11). (13 _F ,
And 13 _R), and the input point moves linearly on the outer periphery of the rotating shaft (6) (L _A) and arranged parallel to the axial cylinder (15), slidably fitted in the axial cylinder (15), wherein An axial piston drive device comprising: an axial piston (16) slidably connected to a swash plate (11) via an output point (D).