JP2820556B2 - Hydraulic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic device as a gear pump or a motor, in which an inlet and an outlet can be reversed by rotating a gear forward and backward.

[0002]

2. Description of the Related Art A gear pump rotates a gear by an electric motor or the like to suck hydraulic oil from an inlet and discharge high-pressure hydraulic oil from an outlet. The gear motor has the same structure as the gear pump, but rotates the gear by supplying high-pressure oil from the inlet. These are provided with various improved products from low pressure to high pressure, and are used as power devices for construction machines and cargo handling machines. Hereinafter, a description will be given using a gear pump. In a high-pressure gear pump, as described in Japanese Utility Model Publication No. 63-15596, a back pressure cavity communicating between the inner side surface of the housing and the back surface of the side plate to the outlet side in order to ensure smooth operation of the gears. The high pressure oil on the outlet side is guided to press the side plate against the end face of the corresponding gear. FIG. 4 shows a main part of such a conventional structure. In the gear pump of FIG. 1, a housing 1 has an inlet 2 and an outlet 3, and a gear 4 and a gear (not shown) that mesh with each other are disposed inside, and the tooth tips of each gear are wrapped by the inner peripheral surface of the housing 1. . The gears are axially supported by bearing holes of the side plates 5 and 6 via their gear shafts. The oil sucked in from the inlet 2 is sequentially fed under pressure while filling the tooth space of each gear, and is discharged from the outlet 3 at a high pressure. Cavities 7 and 8 are provided between the inner side surface of the housing 1 and the back surfaces 5 a and 6 a of the side plates 5 and 6. The cavities 7 and 8 are formed in the back surfaces 5a and 6a, and communicate with the outlet 3 through the passages 3a formed between the housing 1 and the peripheral portions of the side plates 5 and 6. In this structure, when the outlet 3 side is exposed to high-pressure oil, part of the oil enters the cavities 7 and 8 from the passage 3a and
Acts against the end faces of the respective gears, and the back pressure applied to the side plates 5 and 6 maintains the internal leakage between the respective gears and the side plates 5 and 6 at a normal value during operation. 5 and 6 are smoothly brought into contact with the end faces.

[0003]

In the above-mentioned conventional structure, the passage 3a is formed between the housing 1 and the peripheral portions of the side plates 5 and 6, from which the high-pressure oil at the outlet 3 side is supplied. 8, the back plates 5 and 6 are provided with a back pressure, and no consideration is given to the case where each gear is reversed through the drive shaft 9. That is, this type of gear pump can be rotated forward / reverse by an electric motor or the like.
Is used to suck hydraulic oil from the outlet 3 and discharge it from the inlet 2. When the rotation is reversed, the low-pressure oil on the outlet 3 side for sucking the oil is guided to the capacities 7 and 8, so that the back pressure does not occur and a smooth sliding contact state cannot be obtained.

Accordingly, the present invention has been made to solve the above-mentioned problems, and a gear pump or a gear motor capable of forward / reverse rotation can obtain a back pressure function in any case regardless of forward rotation / reverse rotation. It is an object of the present invention to provide a hydraulic device that has been developed.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a housing having an inlet and an outlet, a circumscribing external gear that is incorporated in the housing and meshes with each other, and both ends of the gear. A side plate located on the side and in contact with a corresponding end surface of the gear, and a back pressure cavity provided between an inner surface of the housing and a back surface of each side plate, and hydraulic oil is supplied from the inlet through the inlet. Tooth groove of each gear
Along the inner peripheral surface of the housing while being filled with
In the hydraulic device which is pressure- fed to the outlet side of the housing , the housing defines the cavity and the inlet inside the housing wall.
An inlet-side passage communicating with a groove provided in the
Providing the cavity and the outlet inside the housing wall
An outlet-side passage communicating with a groove provided by
A space provided in the middle of each passage, and each of the passages
And a check valve incorporated in the space of the inlet port.
Path and each check valve of the outlet side passage, the inlet side passage and
Open the high oil pressure side due to oil pressure difference from the outlet side passage, low oil pressure
The gist is to switch freely so that the side is closed.

[0006]

[Function] In the normal operation, the oil sucked from the inlet is
It is sequentially pressure-fed to the outlet side while being filled in the tooth space of each gear,
The oil pressure on the outlet side is increased by suppressing the oil spill on the outlet side. Part of the oil pumped to the outlet side passes through the passage, enters the cavity by opening the check valve provided in the passage, and applies back pressure to the side plate. Since the oil pressure on the inlet side is lower than that on the outlet side, the check valve provided in the passage leading to the inlet side is closed by the oil pressure in the cavity. In the reverse rotation operation, as a result of the gear rotating in the opposite direction, the inlet and outlet sides are reversed, and the opening and closing of the check valves provided in the respective passages also act in reverse. Oil is supplied to apply back pressure to the side plates.

[0007]

EXAMPLES 1 and 2 show an embodiment of the present invention, showing the main structure of the gear pump when the reverse operation and forward schematically. The gear pump shown in FIG.
Have inlets and outlets 12 and 13 communicating with the internal oil flow path, and internally mesh with a gear 14 serving as an external gear and a gear (not shown), and connect the respective gears to side plates 15 and 16 provided at both ends.
In that the teeth are wrapped around the inner peripheral surface of the housing 11 and that the cavities 17, 18 are provided between the back surfaces 15a, 16a of the side plates 15, 16 and the inner surface of the housing 11. It is the same as before. The configuration different from the conventional one is that the cavities 17, 18 are provided through the entrances 12, 13.
Have passages 20 and 21 communicating with the passages.
The check valve 22 is attached to the portion near the cavities 17 and 18. The main structure will be described in detail below.
In this gear pump, the inlet and outlet for sucking oil are changed by forward and reverse rotations of the gears. In the figure, reference numeral 19 denotes a seal member. The dots in the housing 11 indicate oil.

The housing 11 has a cavity 1
7, 18 and the entrance 12 side, and cavities 17, 18
Passages 20 and 21 are provided to communicate with the entrance 13 and the entrance 13 respectively. The passages 20, 21 are provided inside the thick wall of the housing 11, and are located on both sides of the entrances 12, 13 as shown in the figure, and have relatively small diameter narrow groove portions 20a, 21a.
Cavities 17, 1 corresponding to the narrow groove portions 20a, 21a
8 and relatively thick large groove portions 20b and 21b. A space 23 is formed at each intersection of the narrow groove portions 20a, 21a and the thick groove portions 20b, 21b, and a check valve 22 is attached to each space portion 23. Each check valve 22 uses a ball 24 as a valve body, and the ball 24 is swingably incorporated in the space 23. The ball 24 is provided at the opening edge of the space 23 communicating with the narrow groove portions 20a and 21a. 24 is pressed to allow passage 2
Close 0,21. Specifically, cavities 17, 18
When the oil pressure in the narrow groove portion 20a or 21a is high with respect to the oil pressure in the inside, the ball 24 located on the higher side retreats to the rear of the space 23 and communicates with the cavities 17, 18 and its passage. Conversely, when the oil pressure in the narrow groove portion 20a or 21a is low, the ball 24 located on the lower side is pressed by the opening edge while closing the passage while being swung by the oil pressure in the cavities 17 and 18.

Next, the operation of the above gear pump will be described. In this gear pump, an output unit such as an electric motor is connected to a drive shaft 25 having an extended gear shaft of the gear 14, and switching between forward rotation and reverse rotation is performed. Assuming that FIG. 1 is in the normal rotation state, FIG. 2 is in the state of the reverse rotation operation. In the normal rotation operation of FIG. 1, each gear rotates in conjunction with the drive shaft 25, and the oil sucked into the housing 11 from the entrance 12 as shown by the arrow is filled in the respective tooth grooves while being filled in the inner peripheral surface of the housing 11. Along to the other entrance 13 side. By suppressing the discharge of oil at the entrance 13, the entrance 13 has a high oil pressure. Then, a part of the high-pressure oil on the entrance 13 side enters the space 23 through the narrow groove 21a, and opens the check valve 22 to push the ball 24 in the space 23 off.
The cavity 1 passes from the space 23 through the thick groove 21b.
7, 18 are introduced. On the entrance 12 side, the exit side 13
, The check valve 2 provided in the passage 20
2 is closed by the hydraulic pressure of the cavities 17 and 18. That is, the ball 24 in the space 23 is
The narrow groove portion 20a of the space portion 23 due to the high oil pressure in
To close the passage 20. As a result, both side plates 16 and 17 have cavities 17 and 1.
8 receives a back pressure corresponding to the oil pressure in the pump. Due to this back pressure, internal leakage between the gears and the side plates 16, 17 is maintained at a normal value during operation, and a smooth sliding contact state with the gears is maintained.

In the reverse operation shown in FIG. 2, the oil transfer direction is
And the entrance 13 is on the suction side and the entrance 12
Becomes the discharge side with high oil pressure. In this case, a part of the high-pressure oil on the side of the entrance 12 enters the space portion 23 from the narrow groove portion 20a, opens the check valve 22 to push back the ball 24 of the space portion 23, and opens the check groove 22b from the space portion 23. And into the cavities 17, 18. On the doorway 13 side,
Since the oil pressure is lower than the oil pressure on the outlet side 12, the check valve 22 provided in the passage 21 is closed by the oil pressure in the cavities 17 and 18. These operations are the same as described above, and high-pressure oil is supplied to the cavities 17 and 18 to apply back pressure to the side plates 16 and 17.

FIG. 3 shows an example in which the check valve structure is changed. The check valve 32 presses the ball 24 in a closing direction with a predetermined urging force. That is,
The ball 24 is attached to the space 3 with the spring 34 attached.
3, and is pressed against the opening edge of the space 33 communicating with the narrow groove portions 20a and 21a by the urging force of the spring 34 in the normal state, and closes the passages 20 and 21. When the hydraulic pressure in the narrow groove portion 20a or 21a becomes higher than the urging force of the spring 34, the ball 24 on the higher side is pushed against the urging force of the spring 34 and retreats to the rear of the space 33. , Cavities 17, 18
And the passage. With this structure, the back pressure function can be obtained more reliably, and the back pressure is instantaneously secured in any case, for example, when the forward / reverse operation is frequently switched. Thus, the present invention can be variously modified or developed within the scope of the invention.

[0012]

As described above, in the hydraulic apparatus according to the present invention, the passages communicating with the cavity and the inlet and the passage communicating with the cavity and the outlet are provided in the housing, and the check valves are provided in the respective passages. The back pressure can be similarly applied to the side plates not only in the reverse operation but also in the reverse operation. Therefore, in the present invention, a back pressure function can be obtained in any case regardless of whether the rotation is normal or reverse, and the performance is excellent and the application can be expanded.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a gear pump shown as an embodiment of the present invention during a normal rotation operation.

FIG. 2 is a sectional view of a main part of the gear pump during a reverse rotation operation.

FIG. 3 is a sectional view of a main part of a gear pump shown as another embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a gear pump shown as a conventional example.

[Explanation of symbols]

 11 Housing 12,13 Doorway 15,16 Side plate 17,18 Cavity 20,21 Passage 23,32 Check valve.

Claims (1)

(57) [Claims] 1. A housing having an inlet and an outlet, a circumscribing gear that is incorporated in the housing and meshes with each other, and is in contact with a corresponding end face of the gear located at both ends of the gear. A side plate, and a back pressure cavity provided between an inner surface of the housing and a back surface of each side plate, and hydraulic oil is supplied from the inlet to the teeth of each gear.
The other along the inner peripheral surface of the housing while being filled in the groove.
A hydraulic device that is pressure- fed to one of the outlet sides , wherein the housing hows the cavity and the inlet.
Inlet that is in communication with the groove provided inside the jing wall
A mouth passage, the cavity and the outlet housing
The outlet side communication which is communicated by the groove part provided inside the wall
Roads and spaces provided in the middle of each of the passages
If, Yes and the built in the space portion of the passage check valve
And each check valve of the inlet side passage and the outlet side passage,
High oil pressure side due to oil pressure difference between the inlet side passage and the outlet side passage
, And the hydraulic device is freely switched so that the low hydraulic pressure side is closed.