EP4621225A1

EP4621225A1 - Pressure source unit

Info

Publication number: EP4621225A1
Application number: EP23891136.6A
Authority: EP
Inventors: Kenta Kano; Hideki Tanaka; Takanobu Nakamura; Atsuhito HIGUCHI; Yukito Imamura
Original assignee: Kawasaki Heavy Industries Ltd; Kawasaki Jukogyo KK
Current assignee: Kawasaki Heavy Industries Ltd; Kawasaki Motors Ltd
Priority date: 2022-11-15
Filing date: 2023-09-04
Publication date: 2025-09-24
Also published as: KR20250088744A; CN120092132A; US20260126031A1; WO2024105977A1; JPWO2024105977A1

Abstract

A pressure source unit (1) includes: a hydraulic pump (2) including a rotating shaft (21) and a pump casing (22); and an electric motor (6) including an output shaft (61) and a motor casing (62), the output shaft (61) being coupled to the rotating shaft (21) by a coupling structure (4). The pressure source unit (1) further includes a housing (5) that accommodates therein the rotating shaft (21), the output shaft (61), and the coupling structure (4), the housing (5) connecting between the pump casing (22) and the motor casing (62). Hydraulic oil is stored in the pump casing (22), and the hydraulic oil is supplied into the housing (5).

Description

Technical Field

The present disclosure relates to a pressure source unit for use in a hydraulic circuit.

Background Art

Conventionally, there is a known pressure source unit including a hydraulic pump and an electric motor. For example, FIG. 6 of Patent Literature 1 discloses a pressure source unit in which the rotating shaft of a hydraulic pump and the output shaft of an electric motor are coupled to each other by a key and a key groove. In Patent Literature 1, the pressure source unit is referred to as a "hydraulic pressure generator".
In the pressure source unit, the rotating shaft of the hydraulic pump, the output shaft of the electric motor, and the key are accommodated in a sleeve, and a pump casing of the hydraulic pump and a motor casing of the electric motor are connected to each other by the sleeve.

Citation List

Patent Literature

PTL 1: Japanese Laid-Open Patent Application Publication No. H11-314257

Summary of Invention

Technical Problem

In the above-described pressure source unit, various coupling structures other than the key and the key groove are adoptable. There is a desire to lubricate such a coupling structure.
An object of the present disclosure is to provide a pressure source unit capable of lubricating a coupling structure.

Solution to Problem

The present disclosure provides a pressure source unit including: a hydraulic pump including a rotating shaft and a pump casing; an electric motor including an output shaft and a motor casing, the output shaft being coupled to the rotating shaft by a coupling structure; and a housing that accommodates therein the rotating shaft, the output shaft, and the coupling structure, the housing connecting between the pump casing and the motor casing. Hydraulic oil is stored in the pump casing, and the hydraulic oil is supplied into the housing.

Advantageous Effects of Invention

The present disclosure provides a pressure source unit capable of lubricating a coupling structure.

Brief Description of Drawings

FIG. 1 is a sectional view of a pressure source unit according to one embodiment.
FIG. 2 is a sectional view of a part of a first variation of the pressure source unit.
FIG. 3 is a sectional view of a part of a second variation of the pressure source unit.
FIG. 4 is a sectional view of a part of a third variation of the pressure source unit.
FIG. 5 is a sectional view of a fourth variation of the pressure source unit.

Description of Embodiments

FIG. 1 shows a pressure source unit 1 according to one embodiment. The pressure source unit 1 includes: a hydraulic pump 2; an electric motor 6; and a hollow housing 5 located between the hydraulic pump 2 and the electric motor 6. In the present embodiment, the hydraulic pump 2 and the electric motor 6 are located coaxially.
In the present embodiment, the hydraulic pump 2 is a swash plate pump that is one type of axial piston pump. Alternatively, the hydraulic pump 2 may be a bent axis pump that is another type of axial piston pump. Further alternatively, the hydraulic pump 2 may be a different type of pump, such as a vane pump, a gear pump, or a screw pump.
The hydraulic pump 2 includes: a rotating shaft 21; and a pump casing 22, which supports the rotating shaft 21 via bearings 23 and 24 such that the rotating shaft 21 is rotatable. The pump casing 22 is a hollow casing, and a valve plate 31, a cylinder block 32, and a swash plate 36 are accommodated in the pump casing 22.
To be more specific, the pump casing 22 includes: a front wall 22a, which is penetrated by the rotating shaft 21; a valve cover 22b, which faces the front wall 22a in the axial direction of the rotating shaft 21; and a peripheral wall that surrounds a space between the front wall 22a and the valve cover 22b. The valve cover 22b includes a suction passage and a delivery passage.
The valve plate 31 is fixed to the valve cover 22b. The valve plate 31 includes: an arc-shaped suction port that communicates with the suction passage; and an arc-shaped delivery port that communicates with the delivery passage. The suction port and the delivery port are located on the same circumference about the rotating shaft 21.
The cylinder block 32 is fixed to the rotating shaft 21, and rotates together with the rotating shaft 21 while sliding on the valve plate 31. The cylinder block 32 includes cylinder bores 32a. Some of the cylinder bores 32a communicate with the suction port, and some of the other cylinder bores 32a communicate with the delivery port.
Pistons 33 are received in the respective cylinder bores 32a of the cylinder block 32. Shoes 34 are mounted to the heads of the respective pistons 33. In the present embodiment, the shoes 34 slide on a shoe plate 35 fixed to the swash plate 36. Alternatively, the shoes 34 may directly slide on the swash plate 36.
Each piston 33 and the corresponding shoe 34 include an oil passage 37, which extends from the cylinder bore 32a to the distal end surface of the shoe 34. Hydraulic oil is supplied from the cylinder bore 32a to the distal end surface of the shoe 34 through the oil passage 37, and the hydraulic oil that has been supplied to the distal end surface of the shoe 34 lubricates the shoe 34. The hydraulic oil that has lubricated the shoe 34 is stored in the pump casing 22.
The electric motor 6 includes: an output shaft 61; and a motor casing 62, which supports the output shaft 61 via bearings such that the output shaft 61 is rotatable. The motor casing 62 is a hollow casing, and a rotor and a stator are accommodated in the motor casing 62. The rotor is fixed to the output shaft 61, and the stator is fixed to the motor casing 62.
The rotating shaft 21 of the hydraulic pump 2 and the output shaft 61 of the electric motor 6 are coupled to each other by a coupling structure 4. In the present embodiment, the coupling structure 4 includes a sleeve 40, and the sleeve 40 receives therein the rotating shaft 21 and the output shaft 61. The outer peripheral surface of the rotating shaft 21 includes a spline-shaped toothed surface 21a, whereas one end portion of the inner peripheral surface of the sleeve 40 includes a spline-shaped toothed surface 41. The toothed surface 21a and the toothed surface 41 mesh with each other. Similarly, the outer peripheral surface of the output shaft 61 includes a spline-shaped toothed surface 61a, whereas the other end portion of the inner peripheral surface of the sleeve 40 includes a spline-shaped toothed surface 42. The toothed surface 61a and the toothed surface 42 mesh with each other.
However, it is not essential for the coupling structure 4 to include the sleeve 40. An end portion of one of the rotating shaft 21 or the output shaft 61 may be a hollow end portion; the one of the rotating shaft 21 or the output shaft 61 may receive therein the other; and a spline-shaped toothed surface of the rotating shaft 21 and a spline-shaped toothed surface of the output shaft 61 may directly mesh with each other.
The housing 5 connects the pump casing 22 and the motor casing 62 to each other, and the housing 5 accommodates therein the rotating shaft 21, the output shaft 61, and the coupling structure 4. In the present embodiment, the housing 5 is a tubular housing that extends in the axial direction of the rotating shaft 21 and the output shaft 61.
Further, in the present embodiment, the axial direction of the rotating shaft 21 and the output shaft 61 extends horizontally, and a lower portion (e.g., bottom portion) of the housing 5 includes a drain port 51. However, the drain port 51 may be eliminated. The axial direction of the rotating shaft 21 and the output shaft 61 need not be parallel to the horizontal direction, but may be slightly inclined relative to the horizontal direction (the inclination angle is, for example, 10 degrees or less).
In the present embodiment, there is no oil seal between the rotating shaft 21 and the front wall 22a of the pump casing 22. Accordingly, the hydraulic oil is supplied from inside the pump casing 22 into the housing 5 through a gap between the rotating shaft 21 and the front wall 22a. Since an outflow of the hydraulic oil through the drain port 51 is limited, the hydraulic oil is stored in the housing 5. At the time, the oil surface of the hydraulic oil may be present between the lower end and the upper end of the coupling structure 4 such that the coupling structure 4 is partly immersed in the hydraulic oil, or may be present above the upper end of the coupling structure 4 such that the coupling structure 4 is entirely immersed in the hydraulic oil.
Alternatively, there may be an oil seal between the rotating shaft 21 and the front wall 22a of the pump casing 22, and a lower portion of the front wall 22a may include a through-hole that allows the inside of the pump casing 22 and the inside of the housing 5 to communicate with each other.
As described above, in the pressure source unit 1 of the present embodiment, the hydraulic oil is supplied into the housing 5, which accommodates therein the coupling structure 4, and thereby the coupling structure 4 can be lubricated. In a case where the hydraulic oil is stored in the housing 5 such that the coupling structure 4 is partly immersed in the hydraulic oil, the hydraulic oil is agitated in accordance with rotation of the coupling structure 4. At the time, the agitated hydraulic oil gets sprayed over the coupling structure 4, and thereby the entire coupling structure 4 is lubricated. In addition, since the hydraulic oil that is stored in the pump casing 22 is utilized for the lubrication, a structure for the lubrication can be simplified.
In the present embodiment, since the housing 5 includes the drain port 51, the hydraulic oil in the housing 5 can be circulated. This makes it possible to prevent degradation of locally stored lubricating oil, such as encapsulated grease.
Further, the hydraulic oil in the housing 5 is renewed by replacement of the hydraulic oil in the hydraulic circuit. This realizes favorable maintainability.

The present disclosure is not limited to the above-described embodiment. Various modifications can be made without departing from the scope of the present disclosure.
For example, the hydraulic pump 2 may be a tandem pump or parallel pump that includes two piston pump structures, each piston pump structure including the valve plate 31, the cylinder block 32, the pistons 33, the shoes 34, and the swash plate 36.
Further, as shown in FIG. 2, an upper portion (e.g., top portion) of the housing 5 may include an air vent port 52. With this configuration, when the hydraulic oil is supplied into the housing 5, the air in the housing 5 can be discharged from the housing 5 through the air vent port 52.
Still further, as shown in FIG. 3, the axial direction of the rotating shaft of the hydraulic pump 2 and the output shaft 61 of the electric motor 6 may extend vertically, and the hydraulic pump 2 may be positioned below the electric motor 6. The axial direction of the rotating shaft 21 and the output shaft 61 need not be parallel to the vertical direction, but may be slightly inclined relative to the vertical direction (the inclination angle is, for example, 10 degrees or less).
In a case where the axial direction of the rotating shaft of the hydraulic pump 2 and the output shaft 61 of the electric motor 6 extends vertically, an upper portion of the housing 5 may include the air vent port 52. The "upper portion of the housing 5" herein means an upper one-third region of the housing 5 that is obtained when the housing 5 is trisected into three equal regions that are located side by side in the upward-downward direction. According to this configuration, the oil surface of the hydraulic oil stored in the housing 5 can be set to a high position. Desirably, the air vent port 52 is located, on the housing 5, at a position adjacent to the electric motor 6. It is also desirable that the drain port 51 be positioned below the air vent port 52.
Further, as shown in FIG. 4, the housing 5 may include a tubular wall 53, which includes an end surface located at a position higher than the position of the air vent port 52, the tubular wall 53 surrounding the output shaft 61 of the electric motor 6. According to this configuration, the oil surface of the hydraulic oil stored in the housing 5 can be set to a position above the lower end of the air vent port 52.
As in a hydraulic system 1A shown in FIG. 5, which is another variation, the coupling structure 4 may include: a gear 43 fixed to the rotating shaft 21 of the hydraulic pump 2: and a gear 44 fixed to the output shaft 61 of the electric motor 6. A toothed surface of the gear 43 and a toothed surface of the gear 44 may mesh with each other. In FIG. 5, the gears 43 and 44 are bevel gears. Alternatively, the gears 43 and 44 may be spur gears.
The coupling structure 4 need not include toothed surfaces that mesh with each other, but may be configured as a key and a key groove.

The present disclosure provides, as a first mode, a pressure source unit including: a hydraulic pump including a rotating shaft and a pump casing; an electric motor including an output shaft and a motor casing, the output shaft being coupled to the rotating shaft by a coupling structure; and a housing that accommodates therein the rotating shaft, the output shaft, and the coupling structure, the housing connecting between the pump casing and the motor casing. Hydraulic oil is stored in the pump casing, and the hydraulic oil is supplied into the housing.
According to the above configuration, the hydraulic oil is supplied into the housing, which accommodates therein the coupling structure, and thereby the coupling structure can be lubricated. In addition, since the hydraulic oil that is stored in the pump casing is utilized for the lubrication, a structure for the lubrication can be simplified.
As a second mode, in the first mode, the housing may include a drain port. According to this configuration, the hydraulic oil in the housing can be circulated. This makes it possible to prevent degradation of locally stored lubricating oil, such as encapsulated grease.
As a third mode, in the second mode, for example, an axial direction of the rotating shaft of the hydraulic pump and the output shaft of the electric motor may extend horizontally. An upper portion of the housing may include an air vent port, and a lower portion of the housing may include the drain port.
As a fourth mode, in the first or second mode, for example, an axial direction of the rotating shaft of the hydraulic pump and the output shaft of the electric motor may extend vertically, and the hydraulic pump may be positioned below the electric motor.
As a fifth mode, in the fourth mode, an upper portion of the housing may include an air vent port, and the housing may include a tubular wall that includes an end surface located at a position higher than a position of the air vent port, the tubular wall surrounding the output shaft. According to this configuration, the oil surface of the hydraulic oil stored in the housing can be set to a position above the lower end of the air vent port.
As a sixth mode, in the fifth mode, for example, the housing may include a drain port that is located below the air vent port.
As a seventh mode, in any of the first to sixth modes, for example, the coupling structure may include toothed surfaces that mesh with each other.
As an eighth mode, in any of the first to seventh modes, the pump casing may include a front wall that is penetrated by the rotating shaft, and there may be no oil seal between the front wall and the rotating shaft. According to this configuration, the hydraulic oil is supplied from inside the pump casing into the housing through a gap between the rotating shaft and the front wall.
As a ninth aspect, in any of the first to eighth modes, for example, the hydraulic pump may include: a cylinder block fixed to the rotating shaft and including cylinder bores; pistons that are received in the respective cylinder bores; and shoes that are mounted to heads of the respective pistons. The pistons and the shoes may include oil passages, through which the hydraulic oil may be supplied from the cylinder bores to distal end surfaces of the respective shoes. The hydraulic oil that has been supplied to the distal end surfaces of the respective shoes may lubricate the shoes, and may be then stored in the casing pump.

Claims

A pressure source unit comprising:
a hydraulic pump including a rotating shaft and a pump casing;

an electric motor including an output shaft and a motor casing, the output shaft being coupled to the rotating shaft by a coupling structure; and

a housing that accommodates therein the rotating shaft, the output shaft, and the coupling structure, the housing connecting between the pump casing and the motor casing, wherein

hydraulic oil is stored in the pump casing, and the hydraulic oil is supplied into the housing.
The pressure source unit according to claim 1, wherein
the housing includes a drain port.
The pressure source unit according to claim 2, wherein
an axial direction of the rotating shaft of the hydraulic pump and the output shaft of the electric motor extends horizontally, and

an upper portion of the housing includes an air vent port, and a lower portion of the housing includes the drain port.
The pressure source unit according to claim 1 or 2, wherein
an axial direction of the rotating shaft of the hydraulic pump and the output shaft of the electric motor extends vertically, and

the hydraulic pump is positioned below the electric motor.
The pressure source unit according to claim 4, wherein
an upper portion of the housing includes an air vent port, and

the housing includes a tubular wall that includes an end surface located at a position higher than a position of the air vent port, the tubular wall surrounding the output shaft.
The pressure source unit according to claim 5, wherein
the housing includes a drain port that is located below the air vent port.
The pressure source unit according to claim 1 or 2, wherein
the coupling structure includes toothed surfaces that mesh with each other.
The pressure source unit according to claim 1 or 2, wherein
the pump casing includes a front wall that is penetrated by the rotating shaft, and there is no oil seal between the front wall and the rotating shaft.
The pressure source unit according to claim 1 or 2, wherein
the hydraulic pump includes:
a cylinder block fixed to the rotating shaft and including cylinder bores;

pistons that are received in the respective cylinder bores; and

shoes that are mounted to heads of the respective pistons,

the pistons and the shoes include oil passages, through which the hydraulic oil is supplied from the cylinder bores to distal end surfaces of the respective shoes, and

the hydraulic oil that has been supplied to the distal end surfaces of the respective shoes lubricates the shoes, and is then stored in the casing pump.