KR102225495B1 - Hydraulic pump - Google Patents

Abstract

The present invention relates to a hydraulic pump which has two discharge ports, and which is able to have an operation reliability secured even if the pressure is high, to be attached to and installed on an apparatus which receives the supply of hydraulic pressure, and to supply a hydraulic pressure, comprising: a gear unit which includes a driving gear unit installed on the center and a first driven gear unit and a second driven gear unit which are parallelly installed on both sides of the driving gear unit to be driven by the driving gear unit; a pump housing which includes an accommodation unit inside which corresponds to accommodate the gear unit; a support plate installed between the accommodation unit of the pump housing and the gear unit; and a sealing unit inserted into the support plate to seal the part between the support plate and the accommodation unit. The accommodation unit includes: a first driven gear accommodation unit for accommodating the first driven gear; a driving gear accommodation unit formed to be parallel to the first driven gear accommodation unit; and a second driven gear accommodation unit formed to be parallel to the driving gear accommodation unit. On an upper side of the accommodation unit, between the first driven gear accommodation unit and the driving gear accommodation unit, an upper absorption port is formed, and between the driving gear accommodation unit and the second driven gear accommodation unit, an upper discharge port is formed. On a lower side of the accommodation unit, between the first driven gear accommodation unit and the driving gear accommodation unit, a lower discharge port is formed, and between the driving gear accommodation unit and the second driven gear accommodation unit, a lower absorption port is formed.

Description

Hydraulic pump{HYDRAULIC PUMP}

The present invention relates to a hydraulic pump, and more specifically, to a hydraulic pump having two discharge lines.

In automobiles, pumps for driving various types of devices, such as hydraulic pumps that drive DCT (Dual Clutch Transmission), are widely used.

In Korean Patent Publication No. 10-2013-47282, a configuration of a pump for driving a dual clutch is disclosed.

In the hydraulic pump in the prior art, it is driven by a pair of external gears and consists of one discharge port.

Accordingly, there is a problem that a separate accumulator is required to form two discharge pressures using a hydraulic pump having only one discharge port.

In addition, due to this, there is a disadvantage that it is impossible to modularize a hydraulic pump, an accumulator, a solenoid valve, and a valve body into one.

Alternatively, a problem arises in that two hydraulic pumps must be used to form two discharge pressures.

The present invention is to solve the above-described problem, and it is an object of the present invention to provide a hydraulic pump having two discharge ports and ensuring operational reliability even when the discharge pressure is high.

In order to solve the above problems, the present invention is a hydraulic pump attached to a device receiving hydraulic pressure to supply hydraulic pressure, and the driving gear unit installed in the center and the driving gear unit are installed parallel to both sides of the driving gear unit. A gear unit consisting of first and second driven gear units driven by, a pump housing having a corresponding shape to accommodate the gear unit, and a pump housing formed therein, and installed between the receiving unit and the gear unit of the pump housing. A support plate and a sealing part installed to be inserted into the support plate to seal between the support plate and the receiving part, and the receiving part accommodates a first driven gear for receiving the first driven gear And a drive gear receiving portion formed parallel to the first driven gear receiving portion, and a second driven gear receiving portion formed parallel to the driving gear receiving portion, and the first driven gear at the top of the receiving portion An upper suction port is formed between the receiving part and the driving gear receiving part, and an upper discharge port is formed between the driving gear receiving part and the second driven gear receiving part, and the first driven gear is accommodated under the receiving part. A lower discharge port is formed between the part and the drive gear receiving part, and a lower suction port is formed between the driving gear receiving part and the second driven gear receiving part.

In the hydraulic pump of the present invention, the support plate includes a first driven shaft support portion formed to have a shape corresponding to the first driven gear receiving portion, a drive shaft support portion formed to have a shape corresponding to the drive gear receiving portion, and , Consisting of a second driven shaft support portion formed to have a shape corresponding to the second driven gear receiving portion, and a second upper oil injection groove communicating with the upper discharge port is formed on the second driven shaft support plate And, a second lower oil injection groove communicating with the lower discharge port is formed at an upper portion of the second driven shaft support plate.

In the hydraulic pump of the present invention, the sealing portion has a first sealing portion having a shape corresponding to the first sealing portion receiving groove formed in the first driven shaft support portion, and a shape corresponding to the driving shaft receiving groove formed in the driving shaft support portion. The branch is characterized by comprising a second sealing portion and a third sealing portion having a shape corresponding to the third sealing portion receiving groove formed in the second driven shaft support portion.

In the hydraulic pump of the present invention, the first sealing part is composed of a circular-shaped sealing part with an open upper part and a first lip part formed on the left side of the open end, and the second sealing part has a circular shape with a right lower part open. Consisting of a sealing part and a second upper lip formed on the upper side and a second lower lip formed on the lower side, the third sealing part is a circular sealing part with a lower left open and a third lip formed at the lower left end. It is characterized by consisting of wealth.

In the hydraulic pump of the present invention, the second upper lip portion is formed in a c shape, and the opening is arranged to face the upper discharge port in a direction opposite to the upper suction port, and the second lower lip portion is formed in a c shape, and the opening Is disposed toward the lower discharge port in a direction opposite to the lower suction port.

In the hydraulic pump of the present invention, in the second upper lip and the second lower lip, a groove is formed on a bottom surface of an upper horizontal part.

In the hydraulic pump of the present invention, a pressure chamber communicating with the upper discharge port is formed between the upper discharge port and the upper suction port, and a pressure chamber communicating with the lower discharge port is between the lower discharge port and the lower suction port. It is characterized by being formed.

In the hydraulic pump of the present invention, a cantilever-shaped elastic portion having an external shape corresponding to the driving gear receiving portion and having a predetermined thickness is formed at a lower portion of the pressure chamber.

In the hydraulic pump of the present invention, the elastic portion is formed to be spaced apart from the rear surface of the pump housing, so that it is elastically deformable downward by the pressure in the pressure chamber.

In the present invention, it is possible to form two discharge ports in one pump. Accordingly, the pressure accumulator as in the prior art is not required, and it is possible to modularize the hydraulic pump together with the solenoid valve.

In addition, in the hydraulic pump of the present invention, since the pressure fluctuation is controlled through the pressure chamber even when discharging at high pressure, the oil does not communicate with the suction port, thereby preventing loss in suction pressure.

In addition, due to the elastic portion formed in the lower portion of the pressure chamber, the pressure in the pressure chamber is more elastically controlled.

1 is a diagram showing a state in which the hydraulic pump of the present invention is assembled.
2 is an exploded perspective view of the hydraulic pump of the present invention.
3 is a view showing a pump housing in the hydraulic pump of the present invention.
4 is a view showing a support plate in the hydraulic pump of the present invention.
5 is a view showing a sealing part in the hydraulic pump of the present invention.
6 is a view showing an operating state when the discharge pressure of the hydraulic pump of the present invention is a normal pressure.
7 is a view showing a sealing action by the sealing portion when the discharge pressure of the hydraulic pump of the present invention is high.
8 is a diagram showing a sealing action by an elastic portion when the discharge pressure of the hydraulic pump of the present invention is high.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 is a diagram showing a state in which the hydraulic pump of the present invention is assembled. 2 is an exploded perspective view of the hydraulic pump of the present invention.

The hydraulic pump 10 of the present invention includes a pump housing 100, a gear unit 200 installed inside the pump housing 100, and a support plate 300 installed to cover the gear unit 200. ), a sealing part 400 inserted into the support plate 300 and a mounting sealing part 500 installed outside the gear part 200.

The hydraulic pump 10 of the present invention is not installed independently, but is formed to be installed in other devices that must supply hydraulic pressure, such as, for example, a dual clutch for an automobile.

3 is a view showing a pump housing in the hydraulic pump of the present invention.

An accommodating portion (S) forming a space for accommodating the gear portion 200 is formed in the pump housing 100.

The receiving part S includes a first driven gear receiving part 110, a driving gear receiving part 120 formed in parallel with the first driven gear receiving part 110 in a transverse direction, and the driving gear receiving part 120 ) Consists of a second driven gear receiving portion 130 formed in parallel in the transverse direction.

A first driven shaft receiving portion 111 having a cylindrical boss (BOSS) shape for accommodating the driven shaft 211 of the first driven gear portion 210 is formed on the bottom of the first driven gear receiving portion 110.

A first driven shaft receiving groove 112 is formed inside the first driven shaft receiving portion 111 to receive the first driven shaft 211 and having a shape closed from the rear of the pump housing 100.

A first connection groove 113 communicating with the upper suction port UI and the first driven shaft receiving groove 112 is formed on an upper portion of the front end surface of the first driven shaft receiving portion 111.

A driving shaft receiving portion 121 having a cylindrical boss shape for accommodating the driving shaft 221 of the driving gear portion 220 is formed on the bottom of the driving gear receiving portion 120.

A driving shaft receiving groove 122 is formed inside the driving shaft receiving part 121 to receive the driving shaft 221 and having a shape passing through the rear of the pump housing 100 in the axial direction.

A second connection groove 123 connecting the upper suction port (UI) and the drive shaft receiving groove 122 is formed on the front end surface of the drive shaft receiving part 121, and the lower suction port (LI) and the drive shaft are at the bottom. A third connection groove 124 connecting the receiving groove 122 is formed.

A second driven shaft receiving portion 131 in the shape of a cylindrical boss (BOSS) for receiving the driven shaft 231 of the second driven gear portion 230 is formed on the bottom of the second driven gear receiving portion 130. .

A second driven shaft receiving groove 132 is formed in the second driven shaft receiving portion 131 to receive the second driven shaft 231 and having a shape closed from the rear of the pump housing 100.

A fourth connection groove 133 communicating between the lower suction port LI and the second driven shaft receiving groove 132 is formed on the front end surface of the second driven shaft receiving portion 131.

An upper suction port (UI) is formed between the first driven gear receiving part 110 and the driving gear receiving part 120 in the axial front upper part of the receiving part S, and the driving gear receiving part 120 Two upper discharge ports UO are formed between the driven gear receiving portions 130.

A lower discharge port (LO) is formed between the first driven gear receiving unit 110 and the driving gear receiving unit 120 in the lower axial front of the receiving unit S, and A lower suction port LI is formed between the two driven gear receiving portions 130.

A pressure chamber (C) communicating with the upper discharge port (UO) is installed between the upper suction port (UI) and the upper discharge port (UO), and also between the lower suction port (LI) and the lower discharge port (LO). A pressure chamber (C) communicating with the lower discharge port (LO) is installed.

Meanwhile, a cantilever-shaped elastic portion C1 having a constant thickness while having the same external shape as the outer peripheral surface of the driving shaft support portion 320 of the support plate 300 is formed under the pressure chamber C.

The elastic portion C1 may be formed so that the side portion is fixed to the pump housing 100, and is formed to be spaced apart from the housing 100 so that the elastic deformation may be easily installed.

The gear unit 200 is composed of three gear units 210, 220, and 230 that are externally driven by meshing with each other, and a driving gear unit 220 installed in the center and a second unit installed in parallel to the left and right sides of the driving gear unit 220 It consists of the driven gear units (210, 230) of 1,2.

The drive gear unit 220 includes a drive shaft 221 and a drive gear 222 formed around the drive shaft 221. The drive shaft 221 is formed to protrude through the drive gear part 222 in the front and rear, and the rear end of the drive shaft 221 is installed so as to pass through the drive shaft receiving groove 122 of the penetrating shape of the drive shaft receiving part 121 do.

The first and second driven gear units 210 and 230 are formed around the first and second driven shafts 211 and 231 and the first and second driven shafts 211 and 231 and are engaged with the driving gear 222. It consists of gears 212 and 232.

The first and second driven shafts 211 and 231 are formed to protrude forward and backward of the first and second driven gear units 212 and 232, and the rear ends of the first and second driven shafts 211 and 231 are the first and second driven shaft receiving grooves. Supported at (112,132).

4 is a view showing a support plate in the hydraulic pump of the present invention.

The support plate 300 is formed in a form in which three circular support portions are connected, and is formed to have a constant height in the axial direction of the pump housing 100.

Specifically, the support plate 300 is formed of a drive shaft support part 320 formed in the center, a first driven shaft support part 310 and a second driven shaft support part 330 formed on both sides of the drive shaft support part 320.

A first driven shaft receiving groove 311 for receiving the first driven shaft 211 is formed in the center of the first driven shaft support part 310, and a sealing part ( A first sealing portion accommodating groove 312 for accommodating the first sealing portion 411 of the 400) is formed.

A first lip receiving groove 313 for accommodating the first lip 412 of the sealing unit 400 is formed on the upper left of the first driven shaft receiving groove 311, and an upper suction port (UI) is formed at the upper right. A first communication groove 314 to communicate with is formed.

A first oil injection groove 315 communicating with the lower discharge port LO is formed on the lower left side of the first driven shaft support 310.

A drive shaft receiving groove 321 for accommodating the drive shaft 221 is formed in the center of the drive shaft support part 320, and the second sealing part 421 of the sealing part 400 is accommodated around the drive shaft receiving groove 321. A second sealing portion accommodating groove 322 is formed for it.

A second upper lip receiving groove 323A for accommodating the second upper lip 422 of the sealing part 400 is formed on the drive shaft receiving groove 321.

A second lower lip receiving groove 323B for accommodating the second lower lip 423 of the sealing part 400 is formed at the lower left of the driving shaft receiving groove 321, and the lower suction port LI and the lower right A second communication groove 324 to communicate with is formed,

On the other hand, a second upper oil injection groove 325A in the shape of a through groove communicating with the upper discharge port UO is formed on the upper side of the drive shaft support part 320 on the right side of the second upper lip receiving groove 323A.

In addition, a second lower oil injection groove 325B having a through groove shape communicating with the lower discharge port LO is formed on the left side of the second lower lip receiving groove 323B under the driving shaft support part 320.

A second upper oil injection groove 325A in the shape of a through groove communicating with the upper discharge port UO is formed on the right side of the second sealing part receiving groove 322 under the driving shaft support part 320.

A second driven shaft receiving groove 331 for receiving the second driven shaft 231 is formed in the center of the second driven shaft support part 330, and a sealing part ( A third sealing portion receiving groove 332 for accommodating the third sealing portion 431 of 400) is formed.

A third lip receiving groove 333 for accommodating the third lip 432 of the sealing unit 400 is formed on the lower right side of the second driven shaft receiving groove 331, and the lower suction port LI and the lower left are A third communication groove 334 to communicate with is formed.

A third oil injection groove 335 communicating with the upper discharge port UO is formed on the upper left side of the second driven shaft receiving groove 331.

In the present embodiment, the support plate 300 is composed of one, but is not limited thereto. When the pump is driven at high pressure, it is possible to form two or more plurality of plates.

5 is a view showing a sealing part in the hydraulic pump of the present invention.

The sealing part 400 is configured to have a shape to be inserted into the support plate 300.

The sealing part 400 includes a first sealing part 410 having a shape corresponding to the first sealing part receiving groove 312 formed in the first driven shaft support part 310 of the support plate 300, and the driving shaft support part 320 A third having a shape corresponding to the second sealing portion 420 having a shape corresponding to the driving shaft receiving groove 322 formed in) and the third sealing portion receiving groove 332 formed in the second driven shaft support portion 330 It consists of a sealing part 430.

The first sealing part 410 includes a circular sealing part 411 with an open top, a first lip part 412 formed on the left side of the open end, and a protrusion 413 formed on the sealing part 411. Done.

The first lip part 412 is formed in a c shape, and the opening 412A is disposed to face the outside of the pump housing 100 in a direction opposite to the upper suction port UI. 1 It is fitted to the end of the lip receiving groove 313.

The second sealing part 420 includes a circular sealing part 421 in which the lower right side is opened, second upper and lower lip parts 422 and 423 formed at the upper and lower sides, and a protrusion 424 formed in the sealing part 421 Consists of

The second upper lip part 422 is also formed in a c shape, and the opening 422A is disposed to face the upper discharge port UO in a direction opposite to the upper suction port UI, and the first upper lip part formed on the drive shaft support part 320 It is fitted to the end of the receiving groove (323A).

The second lower lip part 423 is also formed in a C shape, and the opening 423A is disposed to face the lower discharge port LO in the opposite direction to the lower suction port LI, so that the first lower lip part formed on the drive shaft support part 320 It is fitted to the end of the receiving groove (323B).

The third sealing part 430 is composed of a circular sealing part 431 in which the lower left is opened, a third lip part 432 formed at the lower left open end, and a protrusion 433 formed in the sealing part 431. .

The third lip part 432 is formed in a c shape, and a third lip part formed on the second driven shaft support part 330 is arranged so that the opened opening faces the outside of the pump housing 100 in a direction opposite to the lower suction port LI. It is fitted to the end of the receiving groove 333.

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It is also possible to configure the second upper lip part 422 and the second lower lip part 423 so that a groove G is formed on the bottom surface of the upper horizontal part.

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6 is a view showing an operating state when the discharge pressure of the hydraulic pump of the present invention is a normal pressure.

Hereinafter, the operation of the hydraulic pump of the present invention configured as described above will be described.

When the drive shaft 212 of the hydraulic pump is driven by a drive source (not shown), the first and second driven gears 212 and 232 rotate while the drive gear 222 is driven.

As a result, oil is introduced through the upper input port (UI) and the lower input port (LI), and the oil introduced through the upper input port (UI) is transferred to the first lip part 412 and the second upper lip part 422. It is sealed by and flows into the first driven gear 212 and the driving gear 222 without leakage.

In addition, the oil introduced through the lower input port LI is sealed by the second lower lip part 423 and the third lip part 432 and flows into the third driven gear 232 and the driving gear 222 without leakage. .

Oil flowing into the upper input port (UI) flows out to the upper output port (UO) by the rotational action of the first driven gear 212 and the drive gear 222, and flows through the lower input port (LI). The third driven gear 232 and the driving gear 222 is rotated to flow out through the lower output port (LO).

To this effect, in the present invention, it is possible to easily configure a hydraulic pump having two discharge ports of an upper output port (UO) and a lower output port (LO) with only a simple configuration.

On the other hand, a part of the oil flowing into the upper input port (UI) flows into the first driven shaft receiving groove 112 through the first connection groove 113 to support the rotation of the first driven shaft 211. It is done.

Some of the oil introduced through the lower input port LI flows into the drive shaft receiving groove 122 and the second driven shaft receiving groove 132 through the third connection groove 124 and the fourth connection groove 133 It serves to support when the drive shaft 221 and the second driven shaft 231 rotate.

7 is a view showing a sealing action by the sealing portion when the discharge pressure of the hydraulic pump of the present invention is high.

When operating by setting the discharge pressure to a very high pressure in the hydraulic pump of the present invention, the pressure discharged from the upper discharge port (UO) increases, so that the drive shaft 221 and the second driven shaft 231 are displaced downward. Can happen.

Accordingly, the portion corresponding to the drive shaft 221 and the second driven shaft 231 in the support plate 300 is also displaced downward, so that the second upper lip part 422 that seals the upper suction port (UI) is formed. It is spaced apart from the bottom surface of the drive shaft support 120 of the pump housing 100 so that a gap (T) can be generated.

When such a gap T occurs, the upper discharge port UO communicates with the upper suction port UI, thereby causing suction loss.

However, in the present invention, the high pressure oil from the upper discharge port UO is introduced into the inside of the support plate 400 through the second upper oil injection groove 325A, and the opening 422A of the second upper lip part 422 Will pressurize.

Therefore, the opening 422A is further widened by the oil pressure, so that the upper horizontal portion of the second upper lip portion 422 is pressed against the bottom of the drive shaft receiving portion 121 of the pump housing 100, even in the case of high temperature discharge pressure. It makes the function of securing the sealing.

The same works even when the pressure of the lower discharge port LO is high.

That is, the high-pressure oil of the lower discharge port LO flows into the support plate 400 through the second lower oil injection groove 325B to press the opening 423A of the second lower lip part 423. .

As a result, the opening 423A is further widened, so that the upper horizontal portion of the second lower lip portion 423 is pressed against the bottom of the drive shaft receiving portion 121 of the pump housing 100, so that sealing is secured even in the case of high temperature discharge pressure. Let it work.

On the other hand, when a groove (G) is formed in the bottom surface of the upper horizontal portion of the second upper lip portion 422, the upper horizontal portion of the second upper lip portion 422 is more elastically pressed against the bottom surface of the drive shaft receiving portion 121 It becomes the function of becoming.

8 is a diagram showing a sealing action by an elastic portion when the discharge pressure of the hydraulic pump of the present invention is high.

In the present invention, when the pressure chamber C is formed to communicate with the upper discharge port UO, the high pressure discharge pressure from the upper discharge port UO flows into the pressure chamber C as shown in FIG. 9A. Through relaxation, the driving shaft 221 and the second driven shaft 231 are prevented from being displaced downward.

In particular, in the case of forming the elastic portion C1 in the form of an arcuate cantilever spaced apart from the rear surface of the pump housing 100 in the lower portion of the pressure chamber C in the pump housing 100, the pressure as shown in FIG. 9B Due to the pressure in the chamber C, the elastic portion C1 is elastically deformed downward.

As the elastic part C1 deforms downward, the pressure in the pressure chamber C is relieved, and the gap T between the elastic part C1 corresponding to the drive shaft support 120 and the support plate 400 is reduced or disappeared. At the same time, since the upper horizontal portion of the second upper lip portion 422 is pressed further, the sealing action is significantly improved.

The same effect occurs even when the pressure chamber C is formed in the lower discharge port LO and the elastic part C1 is installed.

The embodiments described in the present specification and the configurations shown in the drawings are only one of the most preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention. It should be understood that there may be equivalents and variations.

100: pump housing 200: gear unit
300: support plate 400: sealing portion

Claims (9)

As a hydraulic pump that is attached and installed to a device receiving hydraulic pressure to supply hydraulic pressure,
A gear unit comprising a drive gear unit installed in the center and first and second driven gear units installed in parallel on both sides of the drive gear unit and driven by the drive gear unit,
A pump housing having a receiving portion having a corresponding shape therein to accommodate the gear portion,
A support plate installed between the receiving part of the pump housing and the gear part,
It is installed to be inserted into the support plate and comprises a sealing portion for sealing between the support plate and the receiving portion,
The receiving part,
A first driven gear accommodating portion for accommodating the first driven gear,
A driving gear receiving portion formed parallel to the first driven gear receiving portion,
It consists of a second driven gear receiving portion formed parallel to the drive gear receiving portion,
An upper suction port is formed between the first driven gear receiving part and the driving gear receiving part above the receiving part, and an upper discharge port is formed between the driving gear receiving part and the second driven gear receiving part,
A lower discharge port is formed between the first driven gear receiving part and the driving gear receiving part under the receiving part, and a lower suction port is formed between the driving gear receiving part and the second driven gear receiving part,
The support plate,
A first driven shaft support portion formed to have a shape corresponding to the first driven gear receiving portion,
A drive shaft support portion formed to have a shape corresponding to the drive gear receiving portion,
Consisting of a second driven shaft support portion formed to have a shape corresponding to the second driven gear receiving portion,
A second upper oil injection groove communicating with the upper discharge port is formed at an upper portion of the drive shaft support part,
A hydraulic pump, characterized in that a second lower oil injection groove communicating with the lower discharge port is formed under the drive shaft support part. delete The method according to claim 1,
The sealing part,
A first sealing portion having a shape corresponding to the first sealing portion receiving groove formed in the first driven shaft support portion,
A second sealing portion having a shape corresponding to the driving shaft receiving groove formed in the driving shaft support portion,
A hydraulic pump comprising a third sealing portion having a shape corresponding to the third sealing portion receiving groove formed in the second driven shaft support portion. The method of claim 3,
The first sealing part is composed of a sealing part of a circular shape in which the upper part is opened and a first lip part formed on the left side of the open end,
The second sealing part is composed of a circular sealing part in which the lower right side is opened, a second upper lip part formed on the upper side, and a second lower lip part formed on the lower side,
The third sealing portion is a hydraulic pump, characterized in that consisting of a sealing portion having a circular shape in which a lower left portion is opened and a third lip portion formed at the lower left end portion. The method according to claim 4,
The second upper lip portion is formed in a c shape, and the opening is disposed to face the upper discharge port in a direction opposite to the upper suction port,
The second lower lip portion is formed in a c-shape, and an opening is disposed toward the lower discharge port in a direction opposite to the lower suction port. The method of claim 5,
A hydraulic pump, characterized in that a groove is formed on a bottom surface of an upper horizontal portion of the second upper lip portion and the second lower lip portion. The method of claim 6,
A pressure chamber communicating with the upper discharge port is formed between the upper discharge port and the upper suction port,
A hydraulic pump, characterized in that a pressure chamber communicating with the lower discharge port is formed between the lower discharge port and the lower suction port. The method of claim 7,
A hydraulic pump, characterized in that a cantilever-shaped elastic portion having an external shape corresponding to the driving gear receiving portion and having a predetermined thickness is formed under the pressure chamber. The method of claim 8,
The elastic portion is formed to be spaced apart from the rear surface of the pump housing so as to be elastically deformable downward by the pressure in the pressure chamber.

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