JPH0468472B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a so-called cradle type axial piston in which a swash plate having a cylindrical sliding surface is brought into contact with a cylindrical receiving surface on the machine body side to control the inclination angle. Regarding machines.

(Prior art) Conventionally, this type of piston machine was
As disclosed in Japanese Patent No. 232389 and as schematically shown in FIG. An oil supply passage G is provided which communicates an oil supply hole D opened in the head of the piston P installed in the cylinder block C with an oil reservoir O on the back side of the swath plate S. It is supplied between the opposing surfaces of the sliding surface X and the receiving surface Y.

(Problem to be Solved by the Invention) However, in the above-mentioned device, as the cylinder block C rotates, the oil supply hole D opened in the head of the piston P becomes connected to the oil supply passage G provided on the swath plate S side. Each time the piston is engaged, the oil in the piston inner chamber H is supplied through the oil supply path G between the opposing surfaces of the sliding surface X and the receiving surface Y. Regardless of the angle, as long as the cylinder block C is rotating, lubrication is always performed, so for example, in a pump, when the swash plate S is stationary at the maximum inclination position and the pump is operating at the maximum discharge amount. However, oil equivalent to the amount of oil supplied leaked from the inner chamber H.
Difficulties that would lead to a decrease in efficiency could occur.

In the present invention, the inclination angle of the swath plate is changed only when the swath plate changes its inclination angle, that is, when sliding occurs between the opposing surfaces of the cylindrical sliding surface and the receiving surface, and when lubrication is truly required. By introducing control pressure between opposing surfaces to perform control,
To provide an axial piston machine that can smoothly slide while suppressing a decrease in efficiency.

(Means for Solving the Problems) Therefore, the present invention has a cylinder block 5 having a large number of pistons 5a, a contact surface portion 7a for contacting the head side of the pistons 5a on the front surface, and a machine body 1 on the back surface. A swash plate 7 having a cylindrical receiving surface 80 provided on the side and a cylindrical sliding surface 70 facing the opposite side.
and an operating plunger 9 that is operated by control pressure oil guided into the introduction chamber 45 to control the inclination angle of the swash plate 7, in which the receiving surface 80 and the sliding surface 70 are opposed to each other. It is characterized in that an oil supply passage 10 extending from the introduction chamber 45 is opened between the faces.

(Function) When control pressure oil is not introduced into the introduction chamber 45, the operating plunger 9 does not operate, and the swash plate 7 stands still without changing its inclination angle, the cylindrical sliding surface 70 and the cylindrical receiving surface 80 Although no oil is supplied between the opposing surfaces, when control pressure oil is introduced into the introduction chamber 45 and the operation plunger 9 operates to change the inclination angle of the swash plate 7, the oil supply path 10
A part of the control pressure oil is supplied between the opposing surfaces of the cylindrical sliding surface 70 and the cylindrical receiving surface 80 through. This supplied oil acts as a levitation force that lifts the sliding surface 70 of the swash plate 7 from the receiving surface 80, and also forms an oil film between the receiving surface 80 and the sliding surface 70, which causes the sliding surface 70 of the swash plate 7 to float upward. This means that it can be tilted smoothly with fluid lubrication. This lubrication is performed only when sliding occurs between the receiving surface 80 and the sliding surface 70, and lubrication is not performed when the swath plate 7 is stationary at the maximum tilt position. Therefore, wasteful oil consumption associated with oil supply can be suppressed, and the problem of reduced efficiency can be solved.

(Example) In FIG. 2, 1 is a machine body, in which a cylinder block 5 having a large number of pistons 5a is connected via a spline portion 55 to a main shaft 4 which is supported via front and rear bearings 2a and 2b. At the same time, a swash plate 7 is disposed on the front side of the block 5, and has a contact surface portion 7a with which the head of the piston 5a comes into contact with the head of the piston 5a via the shoe 6.
A cylindrical sliding surface 70 provided on the back side is brought into sliding contact with a cylindrical receiving surface 80 of a holder 8 fixed to the machine body 1.

The swash plate 7 has a spring 11 interposed between the cylinder block 5 and the main shaft 4.
and the pin 110 and pressing body 12 that are biased by this.
0, and when driven, is urged against the holder 8 by the pressing force of the spring 11 and the pressure acting on the piston inner chamber 5b.

The shoes 6 are swingably attached to the head of the piston 5a via a sphere 60 integrated at the end thereof, and each shoe 6 is held by a retainer 13.

A valve plate 12 having a high pressure port 12a communicating with the discharge line A and a low pressure port 12b communicating with the suction line B is interposed between the rear side of the cylinder block 5 and the end cap 100.

The cylindrical sliding surface 70 is connected to the high pressure port 12a of the valve plate 12, as clearly shown in FIG.
The high pressure side sliding surface 71 corresponding to the low pressure port 12
A pair of low pressure side sliding surfaces 72 corresponding to b are provided. In addition, correspondingly, the cylindrical receiving surface 80 also has
As shown in FIG. 4, a pair of high-pressure side receiving surfaces 81 and low-pressure side receiving surfaces 82 are provided. Then, the spigot part 7 formed on the swath plate 7 and the holder 8
3 and 83 as guides, between each opposing surface 71 and 8
1, 72 and 82 are arranged to perform arcuate sliding.

Further, as shown in FIG. 1, a connecting arm 50 is fixed to a bracket 74 integrated at the upper end of the swash plate 7, and via the arm 50,
For example, pressure compensator valve (hereinafter referred to as
It is linked to an operation plunger 9 controlled by a PC valve (referred to as a PC valve) 3, and controls its inclination angle from the maximum inclination position shown by the imaginary line m in the figure to the neutral position shown in the figure. The rotation speed can be adjusted individually.

The PC valve 3 includes a spool 31 that slides in the valve hole 30 and a pressing body 32 that opposes the spool 31, and is controlled to move the primary side of the valve hole 30 to the discharge line A and the secondary side to move the operating plunger 9. Pressure oil introduction chamber 4
5 and the tertiary side are respectively connected to the tank line T, and when the pressure in the discharge line A exceeds the set pressure by the pressing body 32, the spool 31 is moved to the position shown in the figure and the discharge is discharged into the introduction chamber 45. Line A
Control pressure oil, which is part of the fluid discharged from the PC valve 3 and is led from the secondary side of the PC valve 3, is introduced. Note that when the pressure in the discharge line A is lower than the pressure set by the pressing body 32, the introduction chamber 45 is opened to the tank line T. Further, the set pressure by the pressing body 32 is variable by an adjustment screw 33.

The operating plunger 9 is supported on both ends by the main body 1 via support tubes 9a and 9b provided on both sides in the length direction, and supports a rotary body 20 freely in rotation in a circular fitting hole 90 provided in the center thereof. One end of the connecting arm 50 is inserted into an insertion hole 21 formed in the rotating body 20. Note that 42 is a spring that urges the plunger 9 in the direction of the maximum inclination angle, and 43 is a bias piston.

In the piston machine configured as described above, an oil supply passage 10 is extended into the machine body 1 from the control pressure introduction chamber 45 for controlling the inclination angle of the swash plate 7, and the oil supply passage 10 is connected to the receiving surface 80 and the sliding surface. 70
An opening is made between the opposing surfaces.

Specifically, as shown in FIG.
A first oil reservoir 8a in the form of a long groove extending along the tilting direction of the swath plate 7 is formed on the high pressure side receiving surface 81, and the oil supply passage 10 is opened in the first oil reservoir 8a. , on the other low pressure side receiving surface 82,
A second oil sump portion 8b is formed with a smaller opening surface than the first oil sump portion 8a, and the second oil sump portion 8b is formed by:
A communication path 8 extending from one side of the first oil sump 8a
The connection is made via c.

With the above configuration, when the pressure in the discharge line A reaches the set pressure or higher and control pressure is introduced into the introduction chamber 45, the swath plate 7 is controlled from the maximum inclination position to the neutral position. ,
Oil in the introduction chamber 45 is supplied to each oil reservoir 8a, 8b via the oil supply path 10. The supplied oil acts as a floating force that lifts the plate 7 from the receiving surfaces 81, 82 of the holder 8, countering the force that presses the swash plate 7 against the receiving surfaces 81, 82. Moreover, an oil film is formed between the opposing surfaces of the sliding surfaces 71, 72 and the receiving surfaces 81, 82, and the swash plate 7 is smoothly tilted in a fluid-lubricated state.

In this case, the oil supply passage 10 opened to the oil reservoirs 8a and 8b extends from the introduction chamber 45, which is a control pressure line, and only when the swath plate 7 is changed from the maximum inclination position to the neutral position. Since lubrication is performed only when lubrication is truly required between the opposing surfaces 71 and 81, 72 and 82, in other words, lubrication is not constantly performed while the cylinder block 5 is rotating as in the past, but by a swath. Since oil is not supplied when the plate 7 is stationary at the maximum inclination position, it is possible to eliminate the amount of oil leaking at maximum discharge in the case of a pump or at maximum rotation in the case of a motor, solving the problem of reduced efficiency. It can be done.

Moreover, the oil supply pressure supplied between the opposing surfaces is the control pressure that moves the operating plunger 9, and hence the discharge pressure, especially when the sliding surfaces 71 and 72 are connected to the receiving surface 8.
1 and 82, so when the swash plate 7 sequentially changes its angle from the maximum inclination position to the neutral position, it is possible to generate an appropriate floating force commensurate with the angle.
Appropriate refueling can be performed at all times.

Furthermore, in this embodiment, the oil supply areas of the oil reservoirs 8a and 8b are made larger in the first oil reservoir 8a on the high pressure side and smaller in the second oil reservoir 8b on the low pressure side. There is also the advantage that the high-pressure side facing surfaces 71 and 81, which have a larger pressing force, can be better lubricated than the high-pressure side facing surfaces 71 and 82, and that the lubricating process can be carried out more efficiently as a whole. or,
Similarly, in this embodiment, the oil supply passage 10 is opened to the first oil reservoir 8a on the high pressure side, and communicates from one side of the first oil reservoir 8a to the second oil reservoir 8b on the low pressure side. Therefore, first, the first oil sump 8a on the high pressure side is filled with oil, and then oil is supplied to the second oil sump 8b, giving priority to oil supply to the high pressure side facing surfaces 71 and 81. This allows for more efficient refueling.

In the above embodiment, the oil reservoirs 8a and 8b were formed on the holder 8 side, but the swath plate 7
Alternatively, in order to simplify the structure, only the first oil reservoir 8a on the high-pressure side with a large pressing force may be provided to supply oil only between the opposing surfaces on the high-pressure side. good.

(Effects of the Invention) The present invention provides an axial piston machine equipped with a so-called cradle type support structure.
Since the oil supply passage 10 extending from the control pressure oil introduction chamber 45 is opened between the opposing surfaces of the cylindrical receiving surface 80 provided on the side and the cylindrical sliding surface 70 on the swash plate 7 side, the control pressure oil is supplied to the introduction chamber 45. is introduced and the swath plate 7 changes its inclination angle, that is, when sliding occurs between the facing surfaces of the cylindrical sliding surface 70 and the receiving surface 80, and oil supply is truly required, no oil is supplied. As a result, the amount of oil leaked during oil supply can be reduced, and the swash plate 7 can slide smoothly while suppressing a decrease in efficiency.

[Brief explanation of the drawing]

Fig. 1 is a top sectional view showing an embodiment of the piston machine according to the present invention, Fig. 2 is a sectional view of the same side, Fig. 3 is a perspective view of the swath plate, Fig. 4 is a perspective view of the holder, FIG. 5 is a schematic side sectional view of a conventional example. 1...Machine body, 5...Cylinder block, 7
...Swatshi plate, 10...Refueling path, 5a
...Piston, 7a...Contact surface portion, 70...Cylindrical sliding surface, 80...Cylindrical receiving surface, 9...Operation plunger, 45...Introduction chamber.

Claims (1)

[Claims] 1. A cylinder block 5 having a large number of pistons 5a, a cylindrical sliding surface 70 having a contact surface portion 7a on the front surface that contacts the head side of the pistons 5a, and a cylindrical sliding surface 70 on the back surface facing a cylindrical receiving surface 80 provided on the machine body 1 side.
An axial piston machine comprising a swash plate 7 having a swash plate 7 and an operating plunger 9 that is operated by control pressure oil led to an introduction chamber 45 to control the inclination angle of the swash plate 7,
An axial piston machine characterized in that an oil supply passage 10 extending from the introduction chamber 45 is opened between opposing surfaces of the receiving surface 80 and the sliding surface 70.