JPS62228677A - Swash plate piston pump - Google Patents

Abstract

PURPOSE:To prevent the vibration of an operation lever and a swash plate by providing a thrust plate on the swash plate of a swash plate piston pump rotatably in the slant direction on the swash plate. CONSTITUTION:A lug 13 extended in parallel with trunnion pins 3 is provided on a swash plate 12, and a thrust plate 17 is provided facing it. A recess 19 corresponding to the lug 13 is formed on the thrust plate 17 so that a gap (1) is formed whene swash plate 12 and the thrust plate 17 are made vertical. Therefore, the thrust late 17 can be rotated within the range of this gap (1), the neutral width when an operation lever is set to a neutral position can be freely set, and the effect by the vibration of a machine can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a swash plate piston pump that controls the discharge amount by adjusting the inclination angle of the swash plate.

(Prior Art) As an example of a swash plate piston pump, there is one as shown in FIG.
The swash plate is rotatable around the trunnion bin 3.

Reference numeral 6 denotes a cylinder block which is coupled to and rotated by an input shaft 7 driven by a drive means not shown. A cylinder (not shown) provided in this cylinder block 6 has a shoe 8 on its head. A piston 9 is fitted into the piston 9 so as to be in sliding contact with the swash plate 2 via a shoe 8. A port block 11 of the housing 1 is provided with a valve plate 10, which is in surface contact with the cylinder block 6.

Thus, the swash plate 2 is rotated to adjust the maximum stroke of the piston 9 according to its inclination angle, thereby controlling the discharge amount.

In other words, if the inclination angle is increased, the stroke of the piston 9 becomes larger, so the discharge amount increases, and if the inclination angle is set to zero (neutral state), the stroke becomes zero.

This type of swash plate piston pump is sometimes used in hydrostatic transmissions such as vehicles, but in this case, by changing the direction of inclination of the swash plate, the vehicle can move forward or
Performs reverse or stop control; in other words, the stop function is activated when the operating lever is held in the neutral position and the tilt angle of the swash plate is set to 0 degrees, and the vehicle is tilted in either direction from this tilt angle of 0 degrees. This allows vehicles, etc. to move forward or backward. Therefore, a good stopping function cannot be obtained unless the tilt angle of the swash plate is reliably set to 0 degrees when the operating lever is held in the neutral position.

However, if there is only one point on the control lever to stop the vehicle, that point may shift due to mechanical vibrations, etc., or if the driver is inexperienced, the control lever must be placed at the stopping point. This makes it more difficult to do so, and poses a safety problem.

Therefore, when the control lever is positioned near the neutral position,
2. Description of the Related Art Conventionally, devices have been proposed in which a linkage mechanism between an operating lever and a swash plate is provided with a certain amount of slack (backlash) so that a vehicle or the like can be stopped reliably.

It is generally known that in a swash plate piston pump, when the swash plate reaches near the neutral state, a self-returning force is generated to try to return to the neutral state. It is designed to utilize self-recovery power.

(Problems to be Solved by the Invention) However, in the conventional device as described above, vibration of the operating lever and swash plate is likely to occur due to the rattling, and the linkage mechanism between the operating lever and swash plate is abraded. However, there was a problem in that the control accuracy of the swash plate inclination angle decreased due to the deformation.

(Means for Solving the Problems) The present invention provides a swash plate piston pump that controls the discharge amount by changing the stroke of a piston according to the inclination angle of the swash plate. The above-mentioned problem is solved by providing the device rotatably in the direction.

(Function) According to the swash plate piston pump of the present invention, when the operating lever is positioned near the neutral position, the thrust plate is moved relative to the cylinder block by the self-returning force of the pump itself to the neutral state. The inclination angle is set to 0 degrees, and the pump is in a neutral state, that is, in a non-discharge state. This no-discharge range can be changed by adjusting the rotation range of the thrust plate relative to the swash plate.

Therefore, the no-discharge range, that is, the neutral width, can be set relatively freely, making it possible to increase the neutral range for lever operation, reducing the effects of machine vibrations, etc., and ensuring reliable operation even if the operator is inexperienced. It is possible to completely reduce the discharge amount of the pump to O and stop the vehicle.

(Example) Hereinafter, the present invention will be described based on the drawings. The same parts as those in the conventional art will be given the same reference numerals, detailed explanation thereof will be omitted, and only different parts will be explained.

FIGS. 1(a) and 1(b) show a first embodiment of the present invention. Reference numeral 12 denotes a swash plate, and the swash plate 12 has a swash plate extending through the center thereof and extending toward the trunnion pin 3. A protrusion 13 having a semicircular cross section is provided.

Also, this swash plate 12 has a thrust plate l? The thrust plate 17 is provided with a recess 18 corresponding to the protrusion 13, and the recess 18 and the protrusion 13 are fitted into each other. When the swash plate 12 and the thrust plate 17 are made perpendicular with these protrusions 13 and recesses 18 fitted together, both of them are 12.17
It is structured so that there is a gap in between, and this gap!
The thrust plate 17 can rotate within a range of . As described above, the thrust plate 17 can rotate within the range of the gap f, but in consideration of its positioning, the thrust plate 17 is inserted into a plurality of spring holes 20 provided in the swash plate 12 on the side facing the swash plate 12. The biasing force of the contracted spring 21 is applied. The biasing force of this spring 21 can be freely adjusted using a set length adjusting screw 22.

Note that in this first embodiment, the protrusion 13 was formed on the swash plate 12 side, and the recess 18 was formed on the thrust plate 17 side.
Of course, they may be reversed. Furthermore, a connector may be fixed to either the swash plate 12 or the thrust plate 17, and a recess corresponding to the connector may be formed in the other.In short, the thrust plate 17 may be rotatable in the direction of inclination. Any configuration may be used.

Therefore, in the first embodiment, the contact surface between the protrusion 13 and the recess 18 is made into a semi-cylindrical shape, but it may be made into other shapes such as a chevron. If a rotation prevention mechanism is installed to prevent rotation around the axis, only a protrusion may be provided on either the thrust plate or the swash plate in a direction parallel to the axis of the trunnion bin 3. The second embodiment is a specific example of this. In FIG. 2, 24 is a swash plate, 25 is a thrust plate, 25a is a protrusion provided on the thrust plate 25, 2
A steel pole 6 is provided between the swash plate 24 and the thrust plate 25 as a mechanism for preventing the thrust plate 25 from rotating around its axis.

In the third embodiment shown in FIG. 3, a gap l is provided between the swash plate 27 and the thrust plate 28, trunnion bins 28 are provided at both ends of the thrust plate 28, and bearings 30 are provided on the swash plate 27. , with this bearing 30, the thrust plate 2
8 is rotatably held.

In the fourth embodiment shown in FIGS. 4(a), (b), and (c), four piston holes 33 are formed in the swash plate 32 at symmetrical positions with respect to its center, and four piston holes 33 are formed in the swash plate 32 at symmetrical positions with respect to the center thereof. A pressing piston 34 is slidably fitted into the holder. A biasing force of a spring 36 which can be adjusted with an adjustment screw 35 is applied to the suppression piston 34, and the hydraulic pressure by the piston 9 provided in the cylinder block 6 is applied to the fluid pressure provided in the housing 1 and the swash plate 32. This pressure piston 34 is acted upon via a channel 37.

In this fourth embodiment, the opposing surface of the thrust plate 38 that faces the swash plate 32 is configured with 2,000 surfaces that are raised from the ends toward the center as shown in the figure. It performs the same function as the protrusion 13 in the example. In this fourth embodiment, hydraulic pressure acts on the pressing piston 34 to press the thrust plate 3B, so the thrust plate 38 can maintain its normal position, and the sliding force between the swash plate 32 and the thrust plate 38 is maintained by the pressing force. It can reduce the contact force and the load on the bearing part.

Note that in order to apply a pressing force to the thrust plate 38, various methods other than the above-mentioned pressing piston 34 can be considered, but the point is that any method can be used as long as it can offset the hydraulic thrust of the piston 9. For example, a pressing piston may be provided on the thrust plate 38 side, and the thrust plate 3B may be pressed by pressure supplied from the swash plate 32 side. Also, the number of pistons may be determined as appropriate.

In the fifth embodiment shown in FIG. 5, a pair of piston holes 33 are formed in a swash plate 42 at vertically symmetrical positions with respect to the center thereof, and a pressing piston 34 is slidably fitted into this hole 33. It is something. This embodiment is basically the same as the fourth embodiment described above, but both pressures are adjusted so that the hydraulic pressure supplied to the suppression piston 34 is the average value of the pressures of the suction and discharge boats 45 and 48 of this pump. The boats 45, 46 are connected to the channel 37 via a channel 48 provided with two throttles 47 of the same characteristics.
I am trying to communicate with. As a result, the piston 9
In addition to canceling out the hydraulic thrust of the press piston 34, it is possible to balance the moment in the tilting direction due to the hydraulic thrust of the pressing piston 34.

In the sixth embodiment shown in FIGS. 6(a), (b), and (c), the swash plate 52 has a swash plate 52 at vertically symmetrical positions with respect to its center.
A pair of spring holes 20 are provided, and the springs 21 for adjusting the positioning of the thrust plate 53 are compressed into the holes 20, and a pair of piston holes 33 are provided at symmetrical positions with respect to the center of the swash plate 52. The suppression piston 3 is inserted into this hole 33.
4.

In any case, in the above-mentioned Embodiment 4.5.6, the thrust plate 38.53 is pushed by the suppressing piston 34, but the effective area of the pressing piston 34 is reduced and the spring force of the spring 36 is increased so that the suppressing piston A part of the hydraulic pressure to 34 may be borne.

Further, although the swash plate shown in each of the above embodiments is of a trunnion type, it may be of any shape such as a half-moon shape.

(Effects of the Invention) As described above, according to the present invention, in the swash plate piston pump that controls the discharge amount by changing the stroke of the piston according to the inclination angle of the swash plate, the thrust plate is attached to the swash plate. Since the swash plate is rotatable in the direction of inclination, when the operating lever is positioned near the neutral position, the thrust plate adjusts the relative inclination angle with the cylinder block by the self-returning force of the pump itself to the neutral state. At 0 degrees, the pump is in a neutral state, that is, in a non-discharging state.

This no-discharge range can be changed by adjusting the rotation range of the thrust plate relative to the swash plate. Therefore, since the no-discharge range, that is, the neutral width, can be set relatively freely, it is possible to widen the neutral range for lever operation, which reduces the effects of machine vibrations, etc., and ensures reliable operation even if the operator is inexperienced. It is possible to completely reduce the discharge amount of the pump to zero and stop the vehicle. Furthermore, when a detent mechanism is used to maintain the neutral position, it can be put to practical use even if the accuracy of the neutral position is lower than in the past, and zero point adjustment becomes very easy. Furthermore, since the thrust plate is installed in a hydraulic oil-filled environment inside the pump case, a damping effect occurs and the swash plate is affected.

Various effects can be obtained, such as significantly reducing the vibration of the lever and also significantly reducing the influence of wear and deformation on the control accuracy of the swash plate inclination angle.

[Brief explanation of drawings]

1 to 6 show embodiments of the swash plate piston pump according to the present invention, FIG. 1(a) is a partially cutaway front view of the main part of the first embodiment, ) is the front view of the swash plate,
Fig. 2 is a front sectional view of the main part of the second embodiment, Fig. 3 is a partially cutaway front view of the main part of the third embodiment, and Fig. 4 shows the fourth embodiment. ) is a partially sectional plan view. (b) is a partially cutaway front view of the main part, (c) is a front view of the swash plate, FIG. 5 is a partially sectional plan view of the fifth embodiment, and FIG. 6 is the sixth embodiment. (a) is a partially sectional plan view of the pump, (b) is a partial front view with a partial cutout of the main part, (c) is a front view of the swash plate, and Fig. 7 is a conventional swash plate piston pump. FIG. 9... Piston, 12.24.2? , 32.42.52... Swash plate, 17
．． 25.28.38.53 Race 11II Thrust Plate. Patent applicant Kayabae Gyo Co., Ltd. Figure 1 (b) Figure 2 (F5) Figure 4 (Oshin (b) (C) Figure 6 (b)

Claims (1)

[Claims] A swash plate piston pump that controls the discharge amount by changing the stroke of the piston according to the inclination angle of the swash plate, characterized in that a thrust plate is provided on the swash plate so as to be rotatable in the direction of inclination of the swash plate. Swashplate piston pump.