JPS5844872B2 - High pressure oil discharge device for fixed swash plate axial piston pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-pressure oil discharge device for a fixed swash plate type axial piston pump.

Conventionally, as a prior known technology of this type of fixed swash plate type axial piston pump, Japanese Patent Application Laid-Open No. 1029-1983 shown in FIG.
There is No. 06.

The pressure oil discharge device disclosed in this axial piston pump has a cylinder block 102 having a plurality of pistons 101 and a drive shaft 103 integrally formed, and the head of the piston 1010 is attached to an inclined surface of a swash plate 104 with a shoe 105. The piston hole 107 of each piston 101 is in elastic contact with the piston hole 107 of each piston 101 and extends inside the drive shaft 103 on the central axis of rotation of the cylinder bronze 21020 to form a discharge passage 106.
The discharge passage 1 is connected to the discharge passage 1 by a communication passage 109 having a check valve 108.
06 in a focused state, and the discharge path 106
On the discharge side of the drive shaft 103, an outlet passage 110 is formed in the radial direction of the drive shaft 1030 by penetrating the outer peripheral surface of the drive shaft 103, and an external discharge passage 112 penetrating to the outside is formed on the pump wall 111 on an extension of the outlet passage 110. Form the cylinder books 2102
reciprocating each piston 101 by 0 rotation;
As a result, the suction port 113, the pump chamber 114 and the swash plate 1
04 into the piston 101,
The sucked oil is discharged by the piston 101 to the discharge passage 106 via the check valve 10B, and the pressure oil discharged from each piston hole 107 is discharged to the discharge passage 1 via the discharge passage 106.
10, pressure oil is bridged from the outlet passage 110 to the external discharge passage 112, and is discharged from the external discharge passage 112 to the outside via the discharge port 115.

However, in the case of this prior art, the drive shaft 103 rotates and the inner circumferential surface of the bearing 116 of the drive shaft 103 on the inner wall of the pump is fixed, so in the bridging discharge portion 117, the outer circumference of the drive shaft 103 is necessarily fixed. A rotational clearance must be provided between the surface and the inner circumferential surface of the bearing 116, and the rotational clearance is made as small as possible to prevent oil leakage, but these tolerances are quite large. It requires precision and is subject to precision machining limitations, making it difficult to manufacture.For this reason, it is necessary to provide lip packing material on both sides, and even with this, for example, 70 C)-
If the pressure oil reaches 1000 to 9/ca, the lip packing material 118 will be damaged by the high pressure of the high pressure oil, eventually causing oil leakage.

This is because the bridging discharge portion 117 is located in a portion where rotational clearance must necessarily be provided.

In view of the above, the present invention provides an axial piston pump with a fixed swash plate that can solve the problem of oil leakage of high-pressure oil by setting the bridging discharge part to a specific part where the rotational clearance is unnecessary. The present invention aims to provide a high-pressure oil discharge device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

In this device, a cylinder block 2 having a plurality of cylindrical pistons 22 is rotatably installed in a pump chamber 9 in a pump cylinder 7, and the head of the piston 220 is connected to an inclined surface 22 of a swash plate 10.
The cylinder block 20 rotates to cause the pistons 22 to reciprocate through the pump chamber 9 and the swash plate 10.
In the swash plate fixed type axial piston pump which sucks oil into the cylinder block 2 and discharges the sucked oil to the outside, a discharge passage 33 is formed on the axis of rotation of the cylinder block 20, and the suction of the discharge passage 33 is The piston holes 24 of each of the pistons 22 are connected in a focused state through a communication passage 35 having a check valve 34 at the side end, and the pump chamber 9 and the swash plate 10 are connected to each other on the extension line of the discharge side end of the discharge passage 33. A high-pressure oil discharge pipe 43 is fixedly disposed through the side wall of the pump cylinder 7, and a bridge portion 50 having a through-flow hole 56 is slidably installed at the discharge side end of the discharge passage 33. , the outer end surface 50a of the bridge section 50 on the high-pressure oil discharge pipe 43 side and the opposing end surface 43a of the high-pressure oil discharge pipe 430 are connected by free sliding of the bridge section 50 in the stopped state and separation at the beginning of discharge start. A spring member 54 is disposed to contact and hold the discharge passage 3 with a weak urging force to prevent
The outer end surface 50a of the bridge section 50 is pushed against the outer end surface 50a of the cylinder block 2 by a thrust force based on the pressure of the pressure oil in the discharge passage 33 acting on the inner end surface 50b of the bridge section 50 perpendicular to the axial direction of the cylinder block 3. This is a high-pressure oil discharge device for a fixed swash plate type axial piston pump, characterized in that it is configured to come into pressure contact with the opposing end surface 43a of the high-pressure oil discharge pipe 430 on the rotation center axis.

It will be explained in further detail.

In this embodiment, a drive shaft 1 and a cylinder block 2 are integrally connected with bolts 2, and the drive shaft 1 and cylinder block 2 are connected through a bearing 6 by a flange plate 3 and an outer cylinder 5, which are integrally connected with bolts 4. The pump cylinder 7 is fixed to the outer cylinder 5 with bolts 8, and the pump cylinder 7 is rotatably installed inside the cylinder.
A pump chamber 9 is formed by the flange panel 3 and the outer cylinder 5, and a suction port 9' communicating with the outside is formed in the wall of the pump cylinder 7 in the pump chamber 9. A through hole 11 is formed to pass through the side of the swash plate 10 and then to the other outer wall, and a locking rod 13 having a flange portion 12 is inserted into the through hole 11. The part 12 is fixed to the pump cylinder 7 with bolts 14, the swash plate 10 is made tiltable about the axis of the locking rod 13, and the angle between the rotation center axis of the cylinder rod 20 and the inclined surface 27 is changed. A discharge amount variable mechanism 16 that varies the discharge amount is disposed, that is, this discharge amount variable mechanism 1
6 is a nut tube 18 with an adjustment bolt 17 screwed into the center.
is fixed to the pump cylinder 7 with a bolt 19, and the tip of the adjustment bolt 17 is brought into contact with the back surface of the swash plate 10 via the abutment rod 20, and by adjusting the protrusion amount of the adjustment bolt 17, the inclined surface 27 is fixed.
The zero angle is variable and the discharge amount is variable, and there are a total of three pistons 22 in this embodiment,
The pistons 22 are inserted into piston holes 24 arranged at 120 degree intervals on the circumference of the cylinder block 2 with the same radius, so as to be able to reciprocate while being biased to protrude in the direction of the swash plate 10 by springs 23. It is brought into elastic contact with the inclined surface 27 of the swash plate 10 via the shoe 26, and in this embodiment, the inclined surface 27 of the swash plate 10
A long semi-circular suction window 30 is formed on the sliding surface 29 of the nut 26 on the top of the shoe 26, and a communication hole 32 is formed in the shoe 26 to communicate the long suction window 30 with the inside of the piston 22.

In the figure, 15 is an O-ring, 21 is a lock nut, and 28 is a C
It has seven molded retaining wheels.

In addition, in this embodiment, a large-diameter portion 33' is formed at the discharge side * wood end of the discharge passage 33, and the opposite end 44 of the high-pressure oil discharge pipe 430 is supported on this large-diameter portion 33' by a bearing 42.
An outer end 45 of the high-pressure oil discharge pipe 43 projects outside the pump chamber 9 and is screwed and fixed to the pump cylinder I.

In addition, in this embodiment, the opening end of the through-hole 56 on the outer end surface 50a of the bridge section 50 has a diameter smaller than the outer diameter D1 of the inner end surface 50b on the opposite side of the bridge section 50, so that the through-flow hole 56 is A hydraulic balance hole 57 having an inner diameter d2 larger than the inner diameter d1 of the hole 56 is formed.

In this case, the thrust force F based on the pressure p of the pressure oil in the discharge passage 33 is as follows.If the outer diameter D2 of the outer end surface 50a is, the contact surface pressure a between the outer end surface 50a and the opposite end surface 43a is as follows. Become.

Of course, the thrust force F in the case without the hydraulic balance hole 57 is as follows.

Although the spring member 54 in this embodiment is a compression spring, the same applies to a disc spring.

Further, the setting pressure of the spring member 54 is as described above.
The spring pressure may be weak enough to prevent the bridge portion 50 from sliding freely when the operation is stopped and from separating at the beginning of discharge,
That is, there is no need for a strong member to prevent oil leakage of high-pressure oil, and if the pumping and discharging operation is performed, a large pressing force can be obtained by the thrust force F, and this spring member 5
This is because the spring pressure in step 4 is no longer necessary.

Further, the main determining factor for the setting pressure of the spring member 54 may be any element that can obtain the optimum small surface pressure a determined experimentally.

In addition, the check valve 34 of this embodiment includes a blind plug 36, a check valve main body 3T, a float 38, a spring 39, a spring receiver 40, an O
It consists of 41 rings.

In the figure, 43' is a discharge port, 46 is an oil feed path, 41 is a lock nut, 48 is a bolt, and 49 is a pressure ring with high wear resistance.

Further, in this embodiment, a key groove 51 extending in the axial direction is formed on the outer peripheral surface of the bridge part 50, a steel ball 52 is fitted into the key groove 51, and the steel ball 52 is locked with a bolt 53. The bridge part 50 is made to be able to slide in the axial direction, but not to rotate.

55 is an O-ring.

Since the present embodiment has the above-mentioned configuration, oil pre-pressurized by a low-pressure pump or the like is fully pumped into the pump chamber 9 through the suction port 9', and the suction hole 31. It is fed into the piston 22 through the long suction window 30 and the communication hole 32, and when operation is started in this state, the cylinder block 2 rotates due to the rotation of the drive shaft 1, and the cylinder block 2 is fixed due to the rotation of the cylinder block 2. Due to the action of the inclined surface 270 of the swash plate 10, each piston 2
2 reciprocates within the piston hole 24, and at this time, when the piston 22 slides in the retracting direction against the spring 23 during a half rotation, it moves on the sliding surface 29 without the long suction window 30. Since the shoes 26 are in contact with each other, the oil in the piston hole 24 is sealed, and the oil in the sealed piston 22 passes through the piston hole 24, the check valve 34, and the communication passage 35. The piston 22 is discharged as high-pressure oil to the discharge passage 33, and during the next half rotation, the piston 22 is released from the spring 23.
When the shoe 26 slides in the protruding direction due to the spring pressure of
is opposed to a long suction window 30, through which the oil in the pump chamber 9 is sucked into the piston 22 through the suction hole 31 and the communication hole 32. At this time, the check valve 34 closes the discharge passage 33. This is done by each piston 22, and the high pressure oil is discharged into the discharge passage 33 in a pulsating manner in a focused state.

The oil thus concentrated and discharged into the discharge passage 33 is bridged to the oil feed passage 46 of the high-pressure oil discharge pipe 43, and is discharged to the outside.

At this time, the spring member 54 maintains the contact between the outer end surface 50a and the opposing end surface 43a at the initial stage of discharge start, and oil leakage at the low pressure is prevented, so that the pressure of the high pressure oil in the discharge passage 33 is effectively acts on the inner end surface 50b of the bridge portion 50 perpendicular to the axial direction of the discharge passage 33, and presses the bridge portion 50 in the direction of minute protrusion by a thrust force based on the pressure, thereby causing the bridge portion to The outer end surface 50a of the high pressure oil discharge pipe 43 is brought into pressure contact with the opposing side surface of the press ring 49, which is the opposing end surface 43a of the high pressure oil discharge pipe 43, thereby preventing oil leakage between the contact surfaces.

As described above, the present invention forms a discharge passage 33 on the central axis of rotation of the cylinder book 220, and converges the piston holes 24 of each piston 22 at the suction side end of the discharge passage 33 by a communication passage 35 having a check valve 34. state, and the discharge part 3
A high-pressure oil discharge pipe 43 is fixedly disposed on an extension line of the discharge side end of the discharge passage 33, passing through the pump chamber 9, the swash plate 10, and the side wall of the pump cylinder 7, and furthermore, the discharge side end of the discharge passage 33 is A piece part 50 having a through hole 56 is slidably installed inside the piece part 5.
The outer end surface 50a on the side of the high pressure oil discharge pipe 43 of 0 and the opposite end surface 43a of the high pressure oil discharge pipe 430 are connected to an extent that prevents free sliding of the bridge part 50 when the operation is stopped and separation at the beginning of discharge start. A spring member 54 is disposed to contact and hold the discharge passage 33 with a weak biasing force, and this is based on the pressure of the pressure oil in the discharge passage 33 acting on the inner end 1sob of the bridge portion 50 perpendicular to the axial direction of the discharge passage 33. The outer end surface 5 of the bridge portion 50 is
0a is configured to be in pressure contact with the opposite end surface 43a of the high pressure oil discharge pipe 43 on the center axis of rotation of the cylinder block 220, so that the original effect is that each piston 22 is reciprocated by the rotation of the cylinder block 20, Oil is sucked into each piston 22 through the inside of the pump chamber 9 and swash plate 10, and the sucked oil is passed through each check valve 34.
When the oil discharged into the discharge passage 33 in a convergent state by the communication passage 35 having a Since the member 54 prevents free sliding of the bridge part 50 when the operation is stopped and oil leakage in the low pressure oil state at the beginning of discharge, the discharge passage 33 is prevented from flowing due to the pressure of the pressure oil in the discharge passage 33. An inner end 150 of the bridge portion 50 perpendicular to the axial direction
Due to the thrust force acting on b, the outer end surface 50a of the bridge portion 50 is slightly slid and brought into pressure contact with the opposing side surface 43a of the high-pressure oil discharge pipe 430. In other words, once the operation is started, the discharge action is stopped. If this is continued, the pressure of the high-pressure oil in the discharge passage 33 will provide the contact force, and the pressure of the very high pressure oil will provide high adhesion between the contact surfaces. Even oil can be reliably discharged without oil leakage.

This is because the consideration of providing a rotational clearance in the prior art is no longer necessary.

In addition, another unique effect of the present invention is that the pressing force is obtained by the pressure of the pressurized oil, so that the pressing force can be varied according to the pressure of the pressurized oil. This means that the contact force is automatically changed to an appropriate pressure according to the pressure. For example, in the case where the contact force is obtained only by a spring member such as a compression spring or a disc spring, the contact force is is held constant, and even in the case of lower pressure oil, a high pressure contact force must be applied between the contact surfaces to prevent oil leakage of high pressure oil. The unnecessary contact force will accelerate the seizure and wear phenomena between the contact surfaces, but there is no such problem, and the appropriate contact pressure that follows the pressure of the pressure oil can be maintained. Therefore, bridging discharge of high-pressure oil can be performed more reliably and efficiently.

Furthermore, since the bridging discharge is performed on the center axis of rotation of the cylinder 220, the element (average speed) of the pv value when considering the problems of frictional work and surface heat generation can be reduced. Therefore, the element of p (average pressure) can be improved to that extent, and as a result, high-pressure oil can be discharged bridgingly without oil leakage while preventing wear and heat generation phenomena.

As described above, the present invention provides a high-pressure oil discharge device for a fixed swash plate type axial piston pump that can fully achieve the intended purpose.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional view, FIG. 2 is a cross-sectional view taken along the line A-A, FIG. 3 is an enlarged sectional view of main parts, and FIG. FIG. 3 is a vertical cross-sectional view of a conventional example. 2... Cylinder block, 7... Pump tube, 9... Pump chamber, 10... Swash plate, 22... Piston, 24 ... Piston hole, 26 ... Shoe, 32 ... Communication path, 33 ... Discharge path, 34 - ... Check valve, 43 ...High pressure hydraulic discharge pipe, 43a...
・Opposite end surface, 50... Bridge section, 50a...
・Outer end face, 50b...Inner end face, 54...
. . . Spring member, 56 . . . Through-flow hole.

Claims (1)

[Claims] 1. A cylinder block having a plurality of pistons is rotatably installed in a pump chamber in a pump cylinder, the head of the piston is brought into elastic contact with the inclined surface of the swash plate via a shoe, and the rotation of the cylinder block causes The swash plate fixed type axial piston pump is configured to reciprocate each piston, suck oil into each piston through the pump chamber and the inside of the swash plate, and discharge the sucked oil to the outside. A discharge passage is formed on the rotation center axis of the cylinder block, and the piston holes of each of the pistons are connected to the suction side end of the discharge passage in a converged state by a communication passage having a check valve, and the discharge passage of the discharge passage A piece part having a high-pressure oil discharge pipe fixedly disposed on an extension line of the side end through the side wall of the pump chamber/swash plate and the pump cylinder, and further having a through-flow hole at the discharge side end of the discharge passage. is slidably installed inside the cylinder, and the outer end surface of the high-pressure oil discharge pipe side of the cylinder and the opposite end surface of the high-pressure oil discharge pipe are connected to each other during free sliding of the bridge part when the operation is stopped and at the beginning of discharge. A spring member is provided to maintain contact with a weak urging force that prevents separation of the
A thrust force based on the pressure of the pressure oil in the discharge passage acting on the inner end face of the bridge perpendicular to the axial direction of the discharge passage causes the outer end face of the bridge to be aligned with the rotation center axis of the cylinder block. A high-pressure oil discharge device in a swash plate fixed type axial piston pump, characterized in that the high-pressure oil discharge device is configured to be in pressure contact with the opposite end surface of the high-pressure oil discharge pipe on a line.