JPH1073074A - Axial piston pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To aim at reduction of mechanical vibration and rotational noise of an axial piston pump by providing more than 3 pieces of drive pin that are arranged at intervals on the inner diameter side from the shaft of a piston device around a drive shaft acting as rotational center, on a cylinder barrel, and by supporting one-side ends of these drive pins after making them pass through a ball bearing. SOLUTION: The attaching hole 1a of a guide pin 2 is provided in the central part on one-side surface of a driving member 1 connected to a motor, etc., and on a concentric circle of this attaching hole 1a, 4 attaching holes 1b extending, at same intervals, in parallel to the attaching hole 1a are provided and respective drive pins 3 are fixed therein by pressure fitting. On the other hand, on a driven member 4 arranged opposite to the driving member 1, a guide pin arranging hole 4a and a driving pin arranging hole 4b are provided and the guide pin arranging hole 4a is formed in a concave surface of such a size on which the spherical head 2a of the guide pin 2 can make turning motion freely. The driving pin arranging hole 4b consists of a cylindrical hole 4b1 for receiving inserted bearing 5 and a driving pin releasing hole 4b2 and the bearings 5 are sliding freely attached to the tip end parts of driving pins 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial piston pump, and more particularly to an axial piston pump in which a driving member and a driven member are connected and engaged by a high-precision constant velocity joint.

[0002]

2. Description of the Related Art A representative example of a swash plate type axial piston pump is disclosed in Japanese Patent Application Laid-Open No. 64-12079. Further, a universal joint for connecting a driving member and a driven member used in the above-described apparatus has been invented by the inventors of the present application and has been studied for practical use. A typical example thereof is a driving pin fixed to one driving member and a slidably mounted driving pin mounted on the driving pin, as known, for example, from JP-A-63-308220 or JP-B-4-72072. , And a universal joint which is connected and engaged with the other driving member via a spherical bearing engaged with the other driving member.

[0003] An invention in which the above publication technique is further improved to improve the constant velocity performance of the joint portion has been made by the present inventors and is known in Japanese Patent Application Laid-Open No. 5-263759. In the present invention, the drive pin is slidably fitted to the drive member, the ball head is formed integrally with the drive pin, and this is engaged with the driven member to form a universal joint.

[0004]

The above-mentioned universal joint is constructed so as to absorb a difference in pitch diameter of a driving pin which is displaced in accordance with a change in the inclination angle between a driving member and a driven member. Are connected by a pair of drive pins,
There is a disadvantage that the speed changes twice per rotation and rotation cannot be transmitted at a constant speed even when the speed approaches the constant speed. Therefore, the problem of mechanical vibration and rotational noise could not be ameliorated as an axial piston pump.

On the other hand, according to the latter universal joint, the bending stress required for transmitting the rotational force is applied to the sliding drive pin, so that the slide resistance is large, and especially at high speed rotation, it becomes a rotational load and has poor followability. Become. Therefore, even in this case, the problem of mechanical vibration and rotational noise cannot be solved even if the speed is constant.

SUMMARY OF THE INVENTION An object of the present invention is to provide an axial piston pump with reduced mechanical vibration and rotational noise, which is simple and easy to provide.

[0007]

According to the present invention, there is provided a cylinder barrel housed in a housing, which rotates integrally with a drive shaft, and receives an axial force of a rotating piston support which is arranged and fixed on an inner surface of the housing. An axial piston pump including a fixed swash plate, a piston device disposed between the piston support and the cylinder barrel, and a drive pin that transmits a rotational force of the cylinder barrel to the piston support, wherein the cylinder barrel includes: And three or more drive pins arranged around the drive shaft and at an inner diameter side of the axis of the piston device, and one end of the drive pin is connected to the piston support. This is achieved by an axial piston pump characterized by being supported through a movably held ball bearing.

Preferably, the present invention is achieved in that one end of the drive pin is fixed to the cylinder barrel by press-fitting.

Preferably, the present invention is attained by arranging and fixing the drive pins on concentric circles of the drive shaft.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

A drive member (drive shaft) 1 which is separately installed and mechanically connected to a drive source such as a motor is machined into a cylindrical shape by cold forging or machine cutting, and has a central portion on one surface thereof. A mounting hole 1a for the guide pin 2 extending parallel to the axis of the member is provided. As shown in FIG. 2, on the concentric circle of the mounting hole 1a, the mounting holes 1 of the drive pins 3 extending at equal intervals and parallel to the mounting hole 1a.
b are provided, and the respective drive pins are fixed by press fitting. Of course, the fixation is not limited to this as long as it can be firmly fixed by welding or plastic deformation bonding.

A driven member (driven shaft) 4, which is arranged to face the driving member 1 at an arbitrary rotation angle, is machined in the same manner as described above, and has a guide facing the mounting holes 1a, 1b. A pin arrangement hole 4a and a drive pin arrangement hole 4b are provided. The guide pin arrangement hole 4a has a concave surface large enough to freely rotate the ball head 2a of the guide pin.

The shape of the receiving surface may be hemispherical. On the other hand, the drive pin arrangement hole 4b is a bearing 5 to be described in detail later.
And a drive pin escape hole 4b provided in communication with the cylindrical hole 4b1 and having a diameter larger than the cylindrical hole diameter.
It consists of two.

The bearing 5 is made of a hard ball such as die steel and is slidably mounted on the tip of the drive pin 3.

Here, the driving member 1 and the driven member 4 are connected via a plurality of driving pins 3, and the respective axes A,
B intersects at the center point 0 of the guide pin 2 at an angle α (160 degrees), and a straight line C connecting the centers of the bearings 5 at symmetrical positions is located on a plane shape that divides the intersection angle α into two equal parts. The bearing 5 is self-aligned and held on the line.

Considering the geometric relationship between the axes A, B, and C in FIG. 3, point P is the center of the bearing 5 and the power transmission point in the figure. Here, assuming that legs perpendicular to the both axes from point P are hA and hB, a straight line connecting point P and point 0 has an intersection angle α.
Is divided into two equal parts, so that hA = hB. Further, the angular velocities of the axis A of the driving member 1 and the axis B of the driven member 4 are respectively ω
Assuming that A and ωB, the peripheral velocities of the two axes A and B around the point P are ωA · hA and ωB · hB, respectively. Here, since the position of the point P is invariable, these peripheral velocities are equal and ωA · hA = ω
B · hB. Therefore, ωA = ωB, and the power transmission point P is always located on a plane that bisects the intersection angle α between both axes, and rotation is transmitted at a constant speed.

In the above-described embodiment, the guide pin is interposed between the driving member and the driven member. However, if the driving member and the driven member are properly maintained at a specified size, the guide pin is particularly used. do not need. If necessary, a dust cover may be provided at the joint to protect the joint from dust.

According to the embodiment of the present invention, a driving pin is fixed to one of the driving member and the driven member, and a ball bearing is mounted on the other end of the driving pin in cooperation with the constant velocity structure. Since it is slidably disposed and connected to the other drive member via the ball bearing, the drive pin slides on the ball bearing according to the rotational position of the drive shaft.

Therefore, even if a bending stress required for transmitting the rotational force is applied to the drive pin, the ball bearing can be moved in the axial direction without difficulty, and the rotation speed is particularly high and the followability is high. This naturally solves the problems of mechanical vibration and rotational noise, and provides a practical constant velocity joint with a simple configuration.

Next, an axial piston pump device using the above constant velocity joint will be described with reference to FIGS.

In the figure, a piston pump device includes a drive shaft 10, a cylinder barrel 11 which rotates with the rotation of the drive shaft 10, a piston 12 which reciprocates in a cylinder bore 11a formed in the cylinder barrel 11, and a piston pump device. A piston support 13 that rotates together with the piston 12 to convert the rotational motion into a linear motion of the piston 12, a drive pin 14 that transmits the rotation of the cylinder barrel 11 to the piston support 13, and a position with an inclination angle α with respect to the drive shaft 10. Thrust bearing 1
6 and a fixed swash plate 15 which is supported through the swash plate 6.

The drive shaft 10 has one end supported on a housing 17 via a roller bearing 18. The other end of the drive shaft 10 has a bearing 2 on the side cover 19.
0, and the cylinder barrel 11 is disposed and fixed via a valve plate 21.

The piston 12 is inserted into each of a plurality of cylinder bores 11 a, and the other end ball head 12 a is connected to and held by a piston support 13 supported at the center of the drive shaft 10.

The fixed swash plate 15 includes a piston support 13.
The outer annular portion 15a is disposed with an inclination angle α with respect to the drive shaft 10 and the positioning pin 2
After being positioned by using the pins 2, they are fixed by pins (not shown) or the like.

The drive pin 14 is arranged concentrically on the inner diameter side of the piston 12 and is press-fitted and fixed in a drive pin insertion hole 11 b provided in the cylinder barrel 11, and the other end is formed on the end face of the piston support 13. It is rotatably inserted and disposed in a ball receiving hole via a ball bearing 23.

The piston pump device has the above configuration,
FIG. 5 shows a VV sectional view thereof. As shown, a drive pin 14 is arranged concentrically around the drive shaft 10 and a piston 12 is arranged concentrically outside the drive shaft 10.

In the piston pump device, when the drive shaft 10 rotates, the cylinder barrel 11 rotates, and a rotational force is transmitted through a drive pin 14 to rotate the piston support 13. Accordingly, the rotation causes the piston 12 to reciprocate and generate a discharge pressure.

The constant velocity of the swash plate type piston device will be described with reference to FIGS. 4 and 6. FIG.

In FIG. 6, if the center axis of the drive shaft 10 is the drive axis A1 and the center axis of the piston support 13 is the driven axis B1, the intersection angle between the drive axis A1 and the driven axis B1 is α1. Further, since the inclination angle of the annular portion 15a of the fixed swash plate 15 which is the contact member of the piston support 13 with respect to the drive axis A1 is α1 / 2, the two drive pins 14 shown are connected to the center of the ball bearing 23. The inclination angle of the plane C1 including the straight line with respect to the drive axis A1 is also α1 / 2. That is, as in the case of the above embodiment, the power transmission point is always the intersection angle α1 between the drive axis A1 and the driven axis B1.
And satisfies the condition of constant velocity.

Therefore, the rotation of the drive axis A1 is transmitted to the driven axis B1 at a constant speed, so that the drive shaft 10 and the piston 1
2 is transmitted at a constant speed. In addition, since the inclination angle α1 / 2 is fixed by the fixed swash plate 15, the transmission can be reliably performed at a constant speed. That is, synchronous rotation can be performed without giving any external force to the piston portion that affects the performance.
The fixed swash plate 15 has a relationship between the annular portion 15a and the plane C1 including a straight line connecting the center of the ball bearing 23 with the aforementioned α1.
As long as the relationship between α and α1 / 2 is satisfied, several types of objects having different inclination angles may be prepared and arbitrarily selected according to the discharge capacity.

According to the embodiment of the present invention, the driving pin is fixedly arranged on one side of the cylinder barrel, and the ball bearing is slidably mounted on the other end of the driving pin in cooperation with the constant velocity structure. Since it is arranged and connected to the piston support via the ball bearing, the drive pin slides on the ball bearing according to the rotational position of the cylinder barrel.

Therefore, even if a bending stress required for transmitting the rotational force is applied to the drive pin, the drive pin can be moved in the axial direction without difficulty, and the rotation speed is particularly high and the followability is high. This naturally provides an axial piston pump using a constant velocity joint with low mechanical vibration and rotational noise.

[0033]

As described above, according to the present invention, an axial piston pump with less mechanical vibration and noise can be provided simply and easily.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal front view of a constant velocity joint according to an embodiment of the present invention.

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

FIG. 3 is a diagram showing a geometric relationship of the constant velocity joint of FIG. 1;

FIG. 4 is a sectional view of an axial piston pump using the constant velocity joint of the present invention.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a geometric relationship diagram of the joint mechanism of FIG. 4;

[Explanation of symbols]

11: cylinder barrel, 12: piston, 13: piston support, 14: drive pin, 15: fixed swash plate.

Claims (4)

[Claims] 1. A cylinder barrel having a plurality of pistons disposed therein, a piston support disposed opposite to the cylinder barrel and holding the other end of the piston, and transmitting a rotational force of the cylinder barrel to the piston support. Do 3
An axial piston pump comprising at least one drive pin, wherein the drive pin is fixedly provided on a cylinder barrel, and one end is supported through a ball bearing rotatably held by the piston support. An axial piston pump characterized by: 2. A cylinder barrel housed in a housing and rotating integrally with a drive shaft, a fixed swash plate disposed on and fixed to an inner surface of the housing and receiving an axial force of a rotating piston support, and the piston. An axial piston pump including a piston device disposed between a support and the cylinder barrel, and a drive pin that transmits a rotational force of the cylinder barrel to the piston support, wherein the cylinder barrel is arranged around the drive shaft. Three or more drive pins arranged around the piston and spaced apart from the shaft of the piston device at an inner diameter side, and one end of the drive pin is rotatably held by the piston support. An axial piston pump characterized by being supported through a bearing. 3. The axial piston pump according to claim 1, wherein one end of the drive pin is fixed to the cylinder barrel by press fitting. 4. The axial piston pump according to claim 1, wherein the drive pin is disposed and fixed on a concentric circle of the drive shaft.