JP2547643B2 - Swash plate type hydraulic rotary machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a swash plate type hydraulic rotating machine such as a swash plate pump and a motor.

[Conventional technology]

Generally, a swash plate type hydraulic rotating machine is, for example, the actual open sho 63-134176.
As shown in Japanese Patent Laid-Open Publication No. 2004-242, in order to reciprocate a piston in a cylinder, a shoe is swingably provided on the tip side of the piston, and the cylinder block rotates on a swash plate inclined with respect to the axis of the cylinder block. Together with this, the shoe is configured to slide. Therefore, FIGS. 4 to 6 show a swash plate type hydraulic motor of this type according to the prior art.

In the figure, reference numeral 1 denotes a casing, which comprises a cylindrical main body casing 1A closed on one axial side and a rear casing 1B fixed to the other axial side of the main casing 1A. A swash plate 2 having a sliding contact surface 2A inclined with respect to the axis of the main body casing 1A is fixed to the inside of the main body casing 1A in the axial direction. 3 is the swash plate 2
Is a valve plate fixed to the inner surface of the rear casing 1B so as to be opposed to the valve casing 3, and a pair of eyebrow ports 4 and 5 are formed on the valve plate 3. It communicates with the formed supply / discharge passage (not shown).

Reference numeral 6 denotes a rotary shaft provided in the casing 1 through bearings 7 and 8 in a state of penetrating the swash plate 2 and the valve plate 3, and 9 denotes a cylinder block fitted to the rotary shaft 6, the cylinder block 9 Rotate while slidingly contacting the valve plate 3. , 10 are a plurality of cylinders facing the swash plate 2 and bored in the axial direction of the cylinder block 9, and each of the cylinders 10 has an eyebrow of the valve plate 3 via a communication passage 11, 11 ,. Model port 4,5
It is designed to communicate with each.

12, 12, ... Are pistons slidably provided in the cylinders 10, 10 ,.
12A is formed. Further, in the axial direction of each piston 12, an oil chamber 13 opening at the center of the bottom of the concave spherical surface portion 12A, the oil chamber 1
A small-diameter oil passage 14 communicating with 3 and a large-diameter oil passage 15 communicating with the small-diameter oil passage 14 are formed.

, 16 are shoes which are swingably connected to the tip end side of the piston 12, and each shoe 16 is a concave spherical surface portion of the piston 12.
Spherical joint 16A that fits into 12A and seal land described later
18 is integrally formed with the disk portion 16B that slides on the sliding contact surface 2A of the swash plate 2. A disk-shaped static pressure pocket 17 is provided at the center of the flat surface of the disk portion 16B of the shoe 16 and has an annular seal land 18 slidably contacting the swash plate 2 on the outer peripheral side thereof. An oil passage hole 19 is formed in the shoe 16 so as to communicate with the static pressure pocket 17 and guide the pressure oil in the cylinder 10 into the static pressure pocket 17.
The shoe 16 formed as described above is brought into contact with the swash plate 2 by the shoe pressing plate 20 so as to slide on the sliding contact surface 2A of the swash plate 2 as the cylinder block 9 rotates. There is.

The prior art is constructed as described above, and its operation will be described below.

Pressure oil discharged from a hydraulic pump (not shown) is supplied into the cylinder 10 sequentially through a supply passage provided in the rear casing 1B, one eyebrow port 4 of the valve plate 3 and a communication passage 11 of the cylinder block 9. It The hydraulic pressure of the pressure oil in the cylinder 10 acts in a direction to extend the piston 12 from the inside of the cylinder 10 and pushes the piston 12 in the axial direction.
Is pressed against the swash plate 2. Since the swash plate 2 is inclined with respect to the axis of the piston 12, the shoe 16 slides on the sliding contact surface 2A and the piston 12 rotates the cylinder block 9 by the reaction force of the pressing force. At the same time, the rotary shaft 6 rotates.

As described above, the cylinder block 9 rotates and each communication passage 11
Is communicated with the eyebrow port 4 on one side, and in the supply stroke in which the pressure oil is supplied into each cylinder 10 and the piston 12 extends from the inside of the cylinder 10, the piston 12 applies a rotational force to the rotating shaft 6.
On the other hand, as the cylinder block 9 rotates, each communication passage 11
Communicates with the eyebrow port 5 on the other side, and the piston 12 is the cylinder
In the discharge stroke of entering the inside of the cylinder 10, the piston 12 discharges the oil liquid in the cylinder 10 to the discharge passage side through the communication passage 11 and the eyebrow port 5 in sequence.

Further, during the operation of the motor described above, the pressure oil in the cylinder 10 is transferred to the large-diameter oil passage 15, in the static pressure pocket 17 provided in the shoe 16.
It is introduced through the small-diameter oil passage 14, the oil chamber 13, and the oil passage hole 19 in order, and the sliding contact surface 2A of the swash plate 2 and the shoe are driven by the hydraulic pressure of the pressure oil.
An appropriate oil film is formed between 16 and 16 to reduce the friction loss between them.

[Problems to be Solved by the Invention]

By the way, according to the prior art, the flat seal land 18 is processed with high accuracy so that the shoe 16 slides smoothly on the swash plate 2. However, when high pressure oil acts, the pressing force of the piston 12 is increased. As a result, the shoe 16 is pressed against the swash plate 2 in a state where the inner peripheral portion 18A of the seal land 18 shown in FIG. 5 has a particularly high contact surface pressure.

By the way, during operation of the hydraulic motor, pressure oil is supplied to the static pressure pockets 17 so that the separating force in the direction of canceling the pressing force by the piston 12 acts on the shoe 16, and the shoe 16 moves on the swash plate 2 at high speed. Since a proper oil film is formed between the shoe 16 and the swash plate 2 due to the sliding of the shoe 16, even if the contact surface pressure of the inner peripheral portion 18A of the seal land 18 becomes high as described above, the shoe 16
Can slide smoothly, and the mechanical efficiency of the hydraulic motor does not decrease.

On the other hand, when the hydraulic motor stops, the pressure oil is not supplied to the static pressure pockets 17. Therefore, if the hydraulic motor is stopped for a long time, the space between the shoe 16 and the swash plate 2 is reduced. May be out of oil film. When the hydraulic motor in such a stopped state is subsequently started, it is difficult to secure a proper oil film between the shoe 16 and the swash plate 2. In this state, the inner peripheral portion 18A of the seal land 18 is When the contact surface pressure of the shoe rises, the shoe 16 and the swash plate 2
The frictional force between and increases significantly.

Especially, the shoe 16 and the swash plate 2 at the time of starting the hydraulic motor.
The friction loss between the motor and the motor accounts for about 40% of the loss of the entire motor, which requires a large starting torque to withstand the load and the static friction at the time of starting.
Since a large frictional force also acts between the swash plate 2 and the swash plate 2, there is a problem that the output torque of the hydraulic motor is significantly reduced due to the frictional loss.

Here, FIG. 6 shows the relationship between the inlet pressure P and the output torque T at the time of starting the hydraulic motor as actual measurement results under the condition that the theoretical displacement of the hydraulic motor is 75.1 cc / rev. ing.

That is, in the characteristic line shown in FIG. 6, when the hydraulic motor is started, its inlet pressure P is changed to pressure P1 (for example, P1 = 350 kg / c).
When gradually increased to m ² ), the output torque T
Increases to a torque value T1 (for example, T1 = 34.6 to 37.1 kg · m). However, even if the inlet pressure P is gradually reduced from the pressure P1 thereafter, the output torque T temporarily maintains the torque value T1, and the output torque T is gradually reduced as the inlet pressure P is further reduced thereafter. Come to do.

In this case, the slope of the characteristic line depends on, for example, the frictional force generated between the shoe 16 of the hydraulic motor and the swash plate 2, and the larger the frictional force, the smaller the slope of the characteristic line and the smaller the frictional force. If so, the inclination becomes large, and it can be brought close to the OA line showing the theoretical output torque characteristic of 100% mechanical efficiency. The reason why the output torque T is temporarily maintained at the torque value T1 when the inlet pressure P is gradually reduced from the pressure P1 is also considered to be the influence of the frictional force generated between the shoe 16 and the swash plate 2. To be

Further, at the time of measuring the output torque, the rotary shaft 6 of the hydraulic motor is slightly rotated, and the measurement work is repeated a plurality of times while sequentially changing the rotation phase, so that the output torque T illustrated in FIG. It has the characteristics. And even if judged from this measurement result, in the conventional technology, the shoe
The torque value T1 of the output torque T due to the large frictional force generated between the 16 and the swash plate 2 (eg plate T1 = 34.6 to 37.1 kg ・ m)
Is small and the variation is large.

By the way, in a machine or device using a hydraulic motor, the output torque at the start is generally larger than the output torque at the time of operation. Therefore, if the output torque at the start is small, the machine or the device cannot be started. It will be. For this reason, it is necessary to use a hydraulic motor having a large capacity or to increase the hydraulic pressure of the hydraulic motor, and there is a problem in that the size of the entire apparatus and the strength of the apparatus must be improved.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a swash plate type hydraulic rotating machine having high output torque efficiency at the time of starting.

[Means for solving the problem]

In order to solve the above-mentioned problems, a feature of the configuration adopted by the present invention is that a seal land slidably contacting the swash plate is attached to a shoe that swings on the swash plate with the rotation of the cylinder block on the tip side of the piston. A static pressure pocket located on the side and supplied with pressure oil from the inside of the cylinder, and a shallow bottom formed between the static pressure pocket and the seal land and surrounding the peripheral edge of the static pressure pocket via a step portion. An auxiliary static pressure pocket is provided, and the auxiliary static pressure pocket has a peripheral edge of the static pressure pocket of 1 to 2 m.
It is surrounded by a radial dimension of m over the entire circumference and its depth dimension is
It is formed to have a minute depth of about 0.001 to 0.003 mm.

[Action]

With the above structure, the shallow auxiliary static pressure pocket formed with a minute depth dimension (about 0.001 to 0.003 mm) between the static pressure pocket of the shoe and the seal land has a stepped portion at the periphery of the static pressure pocket. Since it is surrounded by a radial dimension of 1 to 2 mm over the entire circumference, even if the supply of pressure oil to the static pressure pocket is cut off when the hydraulic rotary machine is stopped, the surface tension of the oil liquid etc. By utilizing this, sufficient oil liquid can be secured in the auxiliary static pressure pocket, and an oil film can be continuously formed between the auxiliary static pressure pocket and the swash plate. When the hydraulic rotary machine is started, even if the contact surface pressure between the shoe and the swash plate becomes high due to the action of high pressure oil, the auxiliary static pressure pocket ensures a proper gap between the shoe and the swash plate. An oil film can be formed, and it is possible to reliably prevent a large frictional force from being generated between the swash plate and the inner peripheral side of the seal land.

〔Example〕

Hereinafter, the first embodiment of the swash plate type hydraulic rotating machine according to the present invention will be described.
A case where the hydraulic motor is used as an example will be described with reference to FIGS. In the embodiment, the same components as those of the prior art shown in FIG.
The description will be omitted.

1 and 2 show the first embodiment of the present invention.

In the figure, 21 indicates a shoe used in this embodiment,
Like the shoe 16 described in the prior art, 21 is composed of a spherical joint means 21A and a disk portion 21B, and the spherical joint portion 21A
Hydrostatic pocket 2 described later extends toward the disk portion 21B.
An oil passage hole 19 for guiding pressure oil is bored in the inside of 2.

Reference numeral 22 denotes a disc-shaped static pressure pocket recessed in the center of the flat surface of the disk portion 21B of the shoe 21, and the static pressure pocket 22 is also formed in substantially the same manner as the static pressure pocket 17 described in the prior art.
The outer peripheral side is a seal land 23 that slides on the sliding contact surface 2A of the swash plate 2. However, an auxiliary static pressure pocket 24 described later is formed between the static pressure pocket 22 and the seal land 23, and an annular step portion 22A is formed between the static pressure pocket 22 and the auxiliary static pressure pocket 24. .

Reference numeral 24 indicates an auxiliary static pressure pocket formed between the static pressure pocket 22 and the seal land 23 on the flat surface side of the disk portion 21B, and the auxiliary static pressure pocket 24 is, for example, 1000 to 50.
It is formed as a shallow concave spherical surface having a large radius of curvature of about 00 mm, and the step portion 22A is formed over the entire circumference of the static pressure pocket 22.
It is designed to be surrounded by.

Here, the auxiliary static pressure pocket 24 has a diameter slightly larger than that of the static pressure pocket 22 and has a radial dimension a of about 1 to 2 mm and a depth dimension b of about b to 0.001 to 0.003 mm. The auxiliary static pressure pocket 24 is formed so that the area ratio of the static pressure pocket 22 and the seal land 23 is not substantially changed. Since the auxiliary static pressure pocket 24 has such a minute depth dimension, it is possible to always secure the oil liquid in the auxiliary static pressure pocket 24 by utilizing the surface tension of the oil liquid and the like. An oil film is continuously formed between the sliding contact surface 2A.

The hydraulic motor according to the present embodiment has the above-mentioned configuration, and its basic operation is substantially the same as that of the conventional art.

However, in the present embodiment, on the flat surface side of the disc portion 21A of the shoe 21, the circumferential edge of the static pressure pocket 22 is located between the static pressure pocket 22 and the seal land 23 and is surrounded by the annular step portion 22A. A shallow static pressure pocket 24 is provided that surrounds the
The auxiliary static pressure pocket 24 has a diameter slightly larger than that of the static pressure pocket 22, and the radial dimension a is, for example, a = 1 to 2 mm, and the depth dimension b is b = 0.001 to 0.003 mm. Since it is formed in a shallow concave spherical shape with a minute depth dimension, the auxiliary static pressure pocket 24 is used by utilizing the surface tension of the oil liquid.
It is possible to always secure the oil liquid therein, and it is possible to continue to form an oil film between the flat surface side of the disk portion 21A of the shoe 21 and the sliding contact surface 2A of the swash plate 2.

Thus, according to the present embodiment, even when the hydraulic motor is stopped and the pressure oil is not supplied to the static pressure pocket 22 of the shoe 21, the auxiliary static pressure pocket 24 is utilized by utilizing the surface tension of the oil liquid. The oil liquid can be secured inside, and the oil film can continue to be formed between the oil liquid and the swash plate 2. Then, even when the high pressure oil acts when starting the hydraulic motor and the contact surface pressure between the shoe 21 and the swash plate 2 becomes high, the auxiliary static pressure pocket 24 causes the shoe 21 and the swash plate 2 to contact each other. A proper oil film can be secured between them, and it is possible to reliably prevent a large frictional force from being generated between the swash plate 2 and the inner peripheral side of the seal land 23.

Further, the relationship between the inlet pressure P and the output torque T at the time of starting the hydraulic motor in the state where the shoe 21 is incorporated is confirmed by conducting an experiment under the same conditions as in the case of the prior art, and FIG. The measurement results shown in are obtained. Also, from this measurement result, the output torque T at the time of starting is compared with the theoretical output torque (mechanical efficiency 100%) in comparison with the hydraulic motor of the prior art.
, And the torque value Ta of the output torque T,
For example, it was possible to increase the size to 37.8 to 39.6 kg · m, and it was confirmed that the variation in the characteristics was small.

Therefore, according to this embodiment, the friction loss between the shoe 21 and the swash plate 2 can be greatly reduced, and the output torque T at the time of starting the hydraulic motor can be effectively increased.
Therefore, the capacity of the hydraulic motor can be made smaller than that of the conventional technology, and various effects such as reduction in size and weight of the entire apparatus can be achieved.

Next, FIG. 3 shows a second embodiment of the present invention, which is characterized by the static pressure pocket 32 of the shoe 31 and the seal land.
The auxiliary static pressure pocket 34 provided between the auxiliary static pressure pocket 33 and the auxiliary static pressure 33 is formed in a shallow flat plate annular shape having a certain minute depth.

Here, the shoe 31 and the static pressure pocket 32 are the first
It is formed similarly to the shoe 21 and the static pressure pocket 22 described in the above embodiment. Further, an annular step portion 32A is formed between the static pressure pocket 32 and the auxiliary static pressure pocket 34, and the auxiliary static pressure pocket 34 covers the peripheral edge of the static pressure pocket 32 over the entire circumference via the step portion 32A. It is supposed to be surrounded. The size of the auxiliary static pressure pocket 34 is the same as the auxiliary static pressure pocket 24 described in the first embodiment, with the radial dimension a being a = 1 to 2 m.
It is desirable to form m so that the dimension b in the depth direction is about b = 0.001 to 0.003 mm.

Thus, even in this embodiment having such a configuration, the auxiliary static pressure pocket 34 provided in the shoe 31 can continue to form an oil film between the sliding contact surface 2A of the swash plate 2 and
Although it is possible to obtain substantially the same operational effect as the first embodiment, particularly in this embodiment, since the auxiliary static pressure pocket 34 is formed in a shallow flat plate annular shape with a minute depth, the auxiliary static pressure pocket 34 is formed. Has advantages such as relatively easy processing.

Incidentally, the auxiliary static pressure pockets 24, 34 of the first and second embodiments
Has a small space of the above-mentioned size, and this does not change the area ratio between the static pressure pocket 22 (32) and the seal land 23 (33).
There is no problem that the amount of pressure oil leaks out of the air and increases.

〔The invention's effect〕

The present invention is as described above in detail, and between the static pressure pocket of the shoe and the seal land, a shallow auxiliary static pressure pocket that surrounds the peripheral edge of the static pressure pocket via a step portion is provided. Since the auxiliary static pressure pocket has a radial dimension of 1 to 2 mm and surrounds the peripheral edge of the static pressure pocket over the entire circumference, the depth dimension is formed to be a minute depth of about 0.001 to 0.003 mm. , Even when the supply of pressure oil to the static pressure pocket is stopped when the hydraulic rotary machine is stopped, it is possible to secure sufficient oil liquid in the auxiliary static pressure pocket by utilizing the surface tension of the oil liquid,
An oil film can be continuously formed between the swash plate and the swash plate. Then, even when the high pressure oil acts at the time of starting the hydraulic rotary machine, and the contact surface pressure between the shoe and the swash plate becomes high,
With the auxiliary static pressure pocket, an appropriate oil film can be secured between the shoe and the swash plate, and the friction loss between the shoe and the swash plate can be reliably reduced. Therefore, it is possible to improve the efficiency of the output torque at the time of starting the hydraulic rotary machine, reduce the capacity of the hydraulic rotary machine, and downsize the entire apparatus using the hydraulic rotary machine. The weight can be reduced and the overall size can be reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a shoe according to a first embodiment of the present invention, and FIG. 2 shows a relationship between an inlet pressure and an output torque at the time of starting a hydraulic motor using the shoe of the first embodiment. Diagram, FIG. 3 is a longitudinal sectional view of the shoe according to the second embodiment, FIGS. 4 to 6 are related to the prior art, FIG. 4 is a sectional view of a swash plate type hydraulic motor, and FIG. FIG. 6 is an enlarged cross-sectional view of the shoe shown in FIG. 4, and FIG. 6 is a diagram showing the relationship between the inlet pressure and the output torque at the time of starting the hydraulic motor using the conventional shoe. 1 ... Casing, 2 ... Swash plate, 6 ... Rotating shaft, 9 ...
Cylinder block, 10 …… Cylinder, 12 …… Piston,
21,31 …… Shoe, 22,32 …… Static pressure pocket, 23,33 ……
Sealland, 24,34 ... Auxiliary static pressure pocket.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Sato, 650 Kazunachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura factory (72) Inventor Isao Nakayama 650, Jinmachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura Plant (56) References Japanese Patent Publication No. 44-30789 (JP, B1) Japanese Patent Publication No. 51-14284 (JP, B1) Japanese Patent Publication No. 49-37206 (JP, B1)

Claims (1)

(57) [Claims] 1. A casing provided with a swash plate, a cylinder block provided on the casing via a rotary shaft and rotating to face the swash plate, and a plurality of cylinders bored in the cylinder block. Swash plate type hydraulic rotation consisting of a slidable piston and a shoe that is swingably provided on the tip side of the piston and that slides on the swash plate as the cylinder block rotates. In the machine, the shoe is formed between a static pressure pocket located on the seal land side in sliding contact with the swash plate and supplied with pressure oil from inside the cylinder, and between the static pressure pocket and the seal land, A shallow auxiliary static pressure pocket that surrounds the peripheral edge of the static pressure pocket via a step portion is provided, and the auxiliary static pressure pocket defines a peripheral edge of the static pressure pocket from 1 to 1.
A swash plate type hydraulic rotary machine characterized in that it is formed so as to be surrounded by a radial dimension of 2 mm over the entire circumference and the depth dimension thereof is a minute depth of about 0.001 to 0.003 mm.