JP3782529B2 - Swash plate type variable displacement piston pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a swash plate type variable displacement piston pump, and more particularly to a high pressure lubrication method for a variable swash plate support portion, which can achieve noise reduction and improved reliability of a pump used at high speed. The present invention relates to an improvement of a capacity piston pump.
[0002]
[Prior art]
In general, as shown in FIGS. 6 and 7, the swash plate type variable displacement piston pump is basically a cam that is slidably contacted with the inner surface 12 of the housing 10 and is tilted at right angles to the axial direction of the rotary shaft 14. And a cylinder 50 including a plurality of pistons 52 that are slidably engaged with the swash plate 30 and formed integrally with the rotary shaft 14. The swash plate 30 is provided with an adjustment mechanism including an inclination adjustment arm 40 for setting the inclination to a predetermined angle.
[0003]
That is, the rotary shaft 14 is pivotally supported at both ends by bearings 14a and 14b, respectively, and the sliding contact portions 32a and 32b of the swash plate 30 with respect to the housing 10 are formed on the cylindrical convex surfaces 34a and 34b on the swash plate 30 side and on the housing 10 side. Corresponding cylindrical concave surfaces (bearing surfaces) 12a and 12b (see FIGS. 8 and 9) are formed. The cylinder 50 has a plurality of pistons 52 arranged in parallel in the axial direction, and the sliding joint portion 52a has a cam surface (flat surface) of the swash plate 30 through the pressing force of the shoe 52b and the spring receiving portion 54. 36 is slidably engaged on 36.
[0004]
The tilt adjustment arm 40 has one end fixed to the swash plate 30 by a stopper 40a, the central portion pivoted to the housing 10 by a support shaft 40b, and the other end (tilting end) 42 having a small diameter. It is formed as a tilting joint portion 48 that cooperates with the piston mechanism 44 and the large-diameter piston mechanism 46. As a result, the swash plate 30 is configured to be tiltable at a predetermined angle.
[0005]
Therefore, according to such a configuration, by tilting the swash plate 30 by a predetermined angle (see FIG. 7), the stroke of the piston 52 in the piston chamber 52c can be changed to change the pump capacity. In this case, the hydrostatic bearing portion with respect to the sliding contact surface of the tilting joint portion 48 of the adjusting mechanism including the housing sliding contact portions 32a and 32b of the swash plate 30 and the tilt adjusting arm 40 is usually discharged pressure oil ( It is configured to lubricate using part of the self-loading pressure oil.
[0006]
[Problems to be solved by the invention]
However, the conventional swash plate lubrication structure having the above structure still has the following disadvantages.
[0007]
That is, in the conventional swash plate lubrication structure, as described above, the lubrication of the hydrostatic bearing portion with respect to the housing sliding contact surfaces 34a and 34b of the swash plate 30 is generally performed via self-load pressure oil. . That is, in the illustrated examples (FIGS. 6 and 7), the pump handling liquid from the pump suction port 16 provided in the housing cover 13 is caused to flow through the reciprocating motion of the piston 52 provided in the cylinder 50 performing the main pump operation. The air is sucked into the piston chamber 52 c through the suction port 15 a provided in the seat 15, and then discharged to the pump discharge port 18 through the discharge port 15 b of the valve seat 15. Part of the pump handling liquid (self-loading pressure oil) discharged in this way is an oil passage 13a in the housing cover 13, an oil passage 10a in the housing 10, an oil chamber 44a and an oil passage 44b in the small diameter piston mechanism 44. First, it is supplied to the hydrostatic bearing portion of the tilting joint portion 48 to lubricate it. Thereafter, the lubricating liquid further passes through the oil passage 40c in the inclination adjusting arm 40 and the oil passage 30a in the swash plate 30, and is supplied to the static pressure bearing portions (housing sliding contact portions) 32a and 32b of the swash plate 30. It is configured to lubricate this.
[0008]
In this case, the self-load pressure oil is applied to one of the convex surfaces of the hydrostatic bearing portions 32a and 32b, that is, the single groove-like lubricating regions 20a and 20b (FIG. 8) provided on the housing sliding contact surfaces 34a and 34b. By introducing the same into the single groove-like lubrication regions 22a and 22b (FIG. 9) provided on the concave surfaces, that is, the swash plate sliding contact surfaces 12a and 12b, the hydrostatic bearing action is exhibited. That is, the convex surface of the swash plate 30 is levitated away from the bearing concave surface of the housing 10 to achieve predetermined lubrication.
[0009]
However, in the conventional swash plate lubrication structure, the hydrostatic bearing action of the swash plate cannot be achieved in the required state in the high-speed operation region of the pump, particularly in this case, when the inclination angle of the swash plate is large. That is, the separation of the swash plate from the housing bearing portion is not levitated and balanced in the required state, so that the operational controllability and efficiency of the pump cannot be achieved in the required state.
[0010]
Therefore, in the high-speed operation region, the suction cylinder 50 increases the suction resistance of the piston 52, and the pressure increase in the piston hole 52c immediately after moving from the suction side to the discharge side causes the cylinder on the discharge side. Compared with 50, since the delay is caused, the pressing force, that is, the reaction force by the spring receiving portion 54 between the swash plate 30 and the housing 10 constituting the bearing portion is reduced.
[0011]
However, the opening force due to the lubricating oil between both the swash plate 30 and the housing 10 increases in proportion to the lubricating oil pressure, that is, the pump discharge pressure, on both the suction side and the discharge side. This is because the area of the lubricating grooves 20a, 20b or 22a, 22b does not vary. For this reason, in the high-speed operation region, the reaction force of the piston 52 (hereinafter referred to as discharge-side reaction force) Fp in the discharge-side cylinder 50 and the separation force (hereinafter referred to as bearing) due to the lubricating oil between the bearing portions. The inequality Fp <Fs is established with Fs). As a result, the inconvenience that the swash plate is floated and unfairly separated from the housing bearing portion has occurred. It is obvious that this inconvenience causes abnormal wear on the bearing portion, thereby inducing noise and the like, impairing operation controllability, increasing the amount of leakage of lubricating oil, and reducing pump efficiency. .
[0012]
Therefore, an object of the present invention is to enable a swash plate for adjusting a discharge flow rate to be adjusted very smoothly in a swash plate type variable displacement piston pump that is operated at a relatively high speed, and to reduce noise and achieve high performance and high performance. It is an object of the present invention to provide a swash plate type variable displacement piston pump capable of performing reliable pump operation.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a swash plate type variable displacement piston pump according to the present invention comprises a swash plate type variable displacement piston pump that adjusts a discharge flow rate by adjusting an inclination angle of the swash plate, and supports the swash plate and the swash plate. In the swash plate type variable displacement piston pump configured to supply and lubricate a part of the discharge pressure oil of the variable displacement piston pump to the sliding surface between the fixed member and the fixed member, the inclination angle of the swash plate is small or large Thus, a supply oil amount adjusting means for adjusting the amount of oil supplied to the sliding surface is provided.
[0014]
In this case, the supply oil amount adjusting means is configured to limit the amount of oil supplied to the sliding surface in a region where the inclination angle of the swash plate is large, and in the region where the inclination angle of the swash plate is small. The amount of oil supplied to the surface can be increased.
[0015]
The supply oil amount adjusting means includes an oil passage communicating with each other inside a swash plate and a cam lever fixed to the swash plate, and an oil passage communicating with the oil passage at a convex spherical head at one end of the cam lever. Is arranged so as to elastically press a small-diameter piston provided inside, and the piston is arranged in an oil chamber for supplying a part of the discharge pressure oil of the variable displacement piston pump, and the piston is adapted to the inclination angle of the swash plate. The piston is configured to be displaced in the axial direction, and the piston is always provided with a throttle passage that communicates the oil passage provided inside with the oil chamber, and is displaced when the inclination angle of the swash plate is set small. It is preferable that an oil passage having a large opening area for communicating the oil passage and the oil chamber is provided.
[0016]
【Example】
Next, embodiments of a swash plate type variable displacement piston pump according to the present invention will be described in detail with reference to the accompanying drawings. For convenience of explanation, the same components as those of the conventional configuration shown in FIGS. 6 to 9 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0017]
First, the configuration of the swash plate type variable displacement piston pump according to the present invention is basically the same as the conventional configuration (FIGS. 6 and 7). Therefore, although it overlaps, it demonstrates briefly again for easy understanding.
[0018]
1 and 2, the swash plate type variable displacement piston pump according to the present invention is basically a cam-like shape that is slidably contacted with the inner surface 12 of the housing 10 and that can be tilted at right angles to the axial direction of the rotary shaft 14. And a cylinder 50 including a plurality of pistons 52 that are slidably engaged with the swash plate 30 and are integrally coupled to the rotary shaft 14.
[0019]
Thus, by tilting the swash plate 30, the stroke of the piston 52 is changed to change the pump capacity, and a part of the pump self-loading pressure oil (lubricating oil) is used to The sliding contact portions (hydrostatic bearing portions) 32a and 32b with respect to the housing 10 are configured to be lubricated (see FIG. 8 or FIG. 9).
[0020]
Further, in the swash plate type variable displacement piston pump of the present embodiment, the lubricating structure (swash plate lubricating structure) of the hydrostatic bearing portions 32a and 32b with respect to the housing 10 of the swash plate 30 in the above configuration is shown in FIGS. The cylindrical slidable contact portion is formed by cylindrical convex surfaces 34 a and 34 b provided on the swash plate 30 and concave surfaces 12 a and 12 b provided on the housing 10.
[0021]
Further, a cam lever 60 is fixed to the swash plate 30 with a stopper 61 such as a bolt, and convex spherical heads 62 and 62 are formed at one end of the cam lever 60. 62, a rod 64 and a receiving member 66 are slidably contacted by respective concave spherical surfaces.
[0022]
The other end of the rod 64 is slidably supported by a concave spherical hole 65 a provided in the small diameter piston 65. The receiving member 66 is slidably supported in a hole 67 a provided at one end of the large-diameter piston 67.
[0023]
In the swash plate type variable displacement piston pump of this embodiment configured as described above, the pump capacity is adjusted by adjusting the tilt angle θ of the swash plate 30 with respect to the axis 14 ′ of the rotating shaft 14. θ is adjusted via the cam lever 60 fixed to the swash plate 30.
[0024]
Therefore, adjustment of the inclination angle θ of the cam lever 60 will be described. That is, the cam lever 60 fixed to the swash plate 30 has the convex spherical heads 62 and 62 at one end thereof supported by the rod 64 and the receiving member 66 from above and below in FIG. The other end of the rod 64 is supported by a small-diameter piston 65. The small-diameter piston 65 has a spring 68 in contact with the other end, which is always in the direction of the spherical heads 62, 62 of the cam lever 60 ( It is elastically pressed upward (in FIG. 2).
[0025]
Further, as shown in FIG. 3, the small diameter piston 65 is slidably inserted into the insertion hole 70a of the cover member 70 surrounding and holding the small diameter piston 65, and is supported in a liquid-tight manner. The small-diameter piston 65 is provided with an oil passage 65b at the center thereof, and the small-diameter piston 65 moves downward by a predetermined amount (x) in the state shown in FIG. A hole 65c configured to open to 72 is provided so as to intersect with the oil passage 65b. In addition, in order to enlarge the opening area, the groove part 65c 'can also be suitably provided in the opening edge part of the said hole part 65c.
[0026]
Further, the extended lower end portion of the oil passage 65b is configured to communicate with the oil chamber 72 through a throttle passage 65d. That is, the oil passage 65b is regardless of the position of the small-diameter piston 65 is connected an oil chamber 72 communicating with via the restriction passage 65d.
[0027]
Further, to the oil chamber 72, a part of the pump handling liquid (self-loading pressure oil) discharged to the pump discharge port 18 provided in the housing cover 13 is supplied to the oil passage 13 a of the housing cover 13 and the oil passage in the housing 10. 10a, and is always supplied through an oil passage 70b provided in the cover member 70.
[0028]
Furthermore, the pressure oil in the oil chamber 72 flows through the throttle passage 65d of the small-diameter piston 65 and after the stroke position of the small-diameter piston 65 moves downward by a predetermined amount (x), through the hole 65c. It is supplied to the oil passage 65b. Further, the pressure oil passes through the oil passage 64 a in the rod 64, the oil passages 60 a and 60 b in the cam lever 60, and the opening 60 c, and further through the oil passage 30 a provided in the swash plate 30. The bearings 32a and 32b of the housing 10 are supplied to sliding surfaces (cylindrical convex surfaces 34a and 34b on the swash plate 30 side and corresponding cylindrical concave surfaces 12a and 12b on the housing 10 side).
[0029]
On the other hand, the large-diameter piston 67 supports the receiving member 66 at one end, and the other end faces the oil chamber 74. Pressure oil adjusted by a control portion (not shown) is supplied to the oil chamber 74. It is comprised so that. In this case, the diameter of the large-diameter piston 67 is set larger than the diameter of the small-diameter piston 65, so that the pressure in the oil chamber 72 acting on the small-diameter piston 65 and the force of the spring 68 are opposed to the cam lever 60. The small diameter piston 65 is moved downward in FIG. As a result, the inclination angle θ of the cam lever 60 with respect to the drive axis 14 ′ can be reduced.
[0030]
The large-diameter piston 67 is slidably inserted into an insertion hole 76a of a cover member 76 that surrounds and holds the large-diameter piston 67, and is supported in a liquid-tight manner. When the required control pressure does not act in the oil chamber 74, the upper end portion of the large-diameter piston 67 contacts the stepped portion 76b provided in the insertion hole 76a, and in this state, the lowest value of the inclination angle θ is Determined.
[0031]
Thus, according to the present invention, the lubricating oil supplied from the oil chamber 72 through the small-diameter piston 65 to the sliding surfaces of the swash plate 30 and the bearing portions 32a and 32b of the housing 10 is The proper amount of lubrication oil that can maintain the surface lubrication in good condition and can always supply a relatively small predetermined amount and discharge it into the pump case from the minute gap between the sliding surfaces. Adjustment means can be configured.
[0032]
Therefore, according to the swash plate type variable displacement piston pumps with oil supply amount adjusting means comprising a structure as described above, is operated at a relatively high speed, and to the inclination angle of the swash plate 30 theta is large, the suction resistance is increased As a result, even when the reaction force of the piston 52 against the swash plate 30 is reduced, the supply of lubricating oil to the sliding surfaces of the swash plate 30 and the bearing portions 32a and 32b of the housing 10 is performed in a state where the inclination angle θ is large. It is supplied only through the throttle passage 65d of the small diameter piston 65. In addition, since a predetermined amount of lubricating oil is discharged from the sliding surface into the case, a pressure loss occurs in the throttle passage 65d, and the pressure on the sliding surface decreases compared to the pump discharge pressure. The opening force between the sliding surfaces of the swash plate 30 is also reduced, and the swash plate 30 does not lift from the guide surface.
[0033]
Further, in a state where the inclination angle θ is relatively small, the lubricating oil is also applied to the sliding surface from an oil passage (groove 65c ′ or hole 65c) having a sufficiently large opening area in addition to the throttle passage 65d of the small-diameter piston 65. Since (self-loading pressure oil) is supplied, the pressure loss in the lubricating oil supply oil passage can be ignored. That is, as shown in FIG. 4, the reaction force of the piston 52 acting on the swash plate 30 is represented by a characteristic curve I in the relationship between the inclination angle θ of the swash plate 30 and the force acting on the swash plate 30. On the other hand, the separation force by the lubricating oil between the swash plate 30 and the bearing portions 32a and 32b of the housing 10 in the present invention is represented by the characteristic curve II (configuration shown in FIG. 3) and the characteristic curve III (FIG. 3). As shown in the case of providing the groove portion 65c ′ in the configuration shown in FIG. 6), the characteristic changes in accordance with the reaction force of the piston 52. However, according to the prior art, the opening force does not change as shown by the characteristic curve IV in FIG. Therefore, according to the present invention, the pressure of the sliding surface is equivalent to the pump discharge pressure, which is commensurate with an increase in the reaction force of the piston (when compared with a state where the inclination angle θ is large) due to the reduction of the suction resistance. Pressure.
[0034]
Further, the piston chamber 52c of the cylinder 50 that performs the main pump operation of the swash plate type variable displacement piston pump according to the present invention for obtaining the pressure oil supplied to the sliding surfaces of the swash plate 30 and the bearing portions 32a and 32b of the housing 10. As shown in FIG. 5, when the inclination angle θ is small, high pressure distribution characteristics are obtained as shown by the solid line, and when the inclination angle θ is large, as shown in FIG. Low pressure distribution characteristics were obtained. As a result, when the inclination angle of the swash plate is increased, it is possible to effectively prevent the occurrence of abnormal wear or the like in the bearing portion.
[0035]
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and many design changes can be made without departing from the spirit of the present invention.
[0036]
【The invention's effect】
As described above, the swash plate type variable displacement piston pump according to the present invention is composed of the swash plate type variable displacement piston pump that adjusts the discharge flow rate by adjusting the inclination angle of the swash plate, and the swash plate and the fixed plate that supports the swash plate. In the swash plate type variable displacement piston pump configured to supply and lubricate a part of the discharge pressure oil of the variable displacement piston pump to the sliding surface between the members, depending on the inclination angle of the swash plate , By providing the supply oil amount adjusting means for adjusting the oil amount supplied to the sliding surface, the swash plate for adjusting the discharge flow rate is adjusted very smoothly even when operated at a relatively high speed. Therefore, stable operation can be achieved, and high-performance and high-reliability pump operation can be realized with low noise.
[Brief description of the drawings]
FIG. 1 is a cross-sectional side view of an essential part showing an embodiment of a swash plate type variable displacement piston pump according to the present invention.
2 is a cross-sectional view taken along line II-II of the swash plate type variable displacement piston pump shown in FIG.
3 is an enlarged cross-sectional view of a main part of the small-diameter piston shown in FIG.
FIG. 4 is a characteristic diagram for comparison and display of the opening force against the reaction force acting on the swash plate in the swash plate type variable displacement piston pump according to the present invention with the opening force of a conventional piston pump.
FIG. 5 is a characteristic diagram showing a pressure distribution characteristic in a piston chamber of a cylinder in a swash plate type variable displacement piston pump according to the present invention.
FIG. 6 is a cross-sectional side view of an essential part showing a configuration of a portion passing through a rotating shaft of a conventional general swash plate type variable displacement piston pump.
7 is a cross-sectional view taken along line VII-VII in FIG.
FIG. 8 is an exploded perspective view showing a lubricating structure in a swash plate of a conventional swash plate type variable displacement piston pump.
FIG. 9 is an exploded perspective view showing another configuration example of a lubricating structure in a swash plate of a conventional swash plate type variable displacement piston pump.
[Explanation of symbols]
10 Housing 10a Oil path 12a, 12b Cylindrical concave surface (sliding contact surface)
13 Housing cover 13a Oil passage 14 Rotating shaft 14 '(Rotating shaft) axis 15 Valve plate 15a Suction port 15b Discharge port 16 Pump suction port 18 Pump discharge port 30 Swash plate 30a Oil passages 32a, 32b Sliding contact parts (hydrostatic bearings) Part)
34a, 34b Cylindrical convex surface (sliding contact surface)
36 Cam surface 50 Cylinder 52 Piston 52a Sliding joint 52b Shoe 52c Piston chamber 54 Spring receiving portion 60 Cam lever 60a, 60b Oil passage 60c Opening 61 Stopper 62 Convex spherical head 64 Rod 65 Small-diameter piston 65a Concave spherical hole 65b Oil passage 65c Hole portion 65c 'Groove portion 65d Restriction passage 66 Receiving member 67 Large diameter piston 67a Hole portion 68 Spring 70 Cover member 70a Insertion hole 70b Oil passage 72 Oil chamber 74 Oil chamber 76 Cover member 76a Insertion hole 76b Stepped portion

Claims (3)

It consists of a swash plate type variable displacement piston pump that adjusts the discharge flow rate by adjusting the inclination angle of the swash plate, and the discharge pressure of this variable displacement piston pump is placed on the sliding surface between the swash plate and the fixed member that supports it. In the swash plate type variable displacement piston pump configured to supply and lubricate a part of oil, supply oil amount adjusting means for adjusting the amount of oil supplied to the sliding surface according to the inclination angle of the swash plate A swash plate type variable displacement piston pump characterized by being provided. The supply oil amount adjusting means is configured to limit the amount of oil supplied to the sliding surface in a region where the inclination angle of the swash plate is large, and to supply the sliding surface in a region where the inclination angle of the swash plate is small. The swash plate type variable displacement piston pump according to claim 1, wherein the swash plate type variable displacement piston pump is configured to increase the amount of oil. The supply oil amount adjusting means has an oil passage communicating with each other inside the swash plate and a cam lever fixed to the swash plate, and an oil passage communicating with the oil passage is provided inside the convex spherical head at one end of the cam lever. The provided small-diameter piston is disposed so as to be elastically pressed, and the piston is disposed in an oil chamber that supplies a part of the discharge pressure oil of the variable displacement piston pump, and the piston is arranged in accordance with the inclination angle of the swash plate. The piston is provided with a throttle passage that always communicates an oil passage provided in the piston with the oil chamber, and is displaced when the inclination angle of the swash plate is set to be small. The swash plate type variable displacement piston pump according to claim 1 or 2, wherein an oil passage having a large opening area is provided to communicate between the oil chamber and the oil chamber.

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