Electric Hydraulic Pump

Abstract

In an electric hydraulic pump that uses an integrated rotating shaft and permanent magnet motor, the problem of iron powder in the hydraulic oil adhering to the rotating shaft is solved while maintaining strength, workability, and cost. [Solution] The pump comprises a pump main body 110 which uses a pump rotor 112 to suck in and discharge hydraulic oil, an electric motor section 120 which includes a motor rotor 123 using a permanent magnet 123a, a rotating shaft 130 which rotates the pump rotor 112 and the motor rotor 123 coaxially and integrally, and an oil seal 140 which seals the gap between the outer periphery of the rotating shaft 130 and the motor side end of the pump case 111. The rotating shaft 130 is coaxially connected via a non-magnetic joint 133 to a pump side rotating shaft 131 which is made of magnetic steel and has the pump rotating element 112 fixed thereto, and a motor side rotating shaft 132 which is made of magnetic steel and has the motor rotor 123 fixed thereto.

Description

[Technical field]

[0001] The present invention relates to an electric hydraulic pump. [Background technology]

[0002] Conventionally, in response to the demand for smaller hydraulic pumps, a configuration has been proposed in which an electric motor and a hydraulic pump are driven by a rotating shaft that is an integral part of a pump drive shaft and a motor output shaft. In addition, in response to the demand for power saving in hydraulic pumps, a motor that employs a permanent magnet in the motor rotor has been adopted.

[0003] For example, Patent Document 1 discloses a hydraulic pump in which the drive shaft of the inner rotor of an internal gear pump and the output shaft of an electric motor are integrated. Patent Document 2 discloses a hydraulic pump in which the drive shaft of the inner rotor of an internal gear pump and the output shaft of a permanent magnet motor are integrated. Patent Document 3 discloses a hydraulic pump in which the rotating shaft of a vane pump and the output shaft of an electric motor are coaxially coupled. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-67214 [Patent Document 2] Patent Publication No. 2013-169136 [Patent Document 3] Patent Publication 2019-206919 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a motor using a permanent magnet is used as the electric motor and the pump drive shaft and the motor output shaft are integrated, the surface of the rotating shaft may be slightly magnetized by the magnetic force of the magnet, and a weak magnetic force may be generated at the contact point of the rotating shaft with the hydraulic oil. On the other hand, the hydraulic oil passing through the hydraulic pump may contain fine iron powder, and iron powder generated during the initial operation stage of the hydraulic pump may be mixed into the hydraulic oil. Such iron powder may adhere to the rotating shaft due to the magnetic force, remain on the rotating shaft, and become lumps, which may bite into the sliding parts and cause wear on the sliding parts.

[0006] As a measure to address the problem of magnetization of the rotating shaft, Patent Document 2 proposes making the rotating shaft out of a non-magnetic metal. However, making the entire rotating shaft out of a non-magnetic metal, for example, aluminum or stainless steel, has problems in terms of strength, workability, and cost. In addition, there is also the problem that the know-how of processing conventional magnetic steel materials cannot necessarily be used.

[0007] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide an electric hydraulic pump that employs a coaxially coupled rotating shaft and permanent magnet motor, which has excellent strength, workability and cost, and can solve the problem of iron powder in the hydraulic oil adhering to the rotating shaft. [Means for solving the problem]

[0008] (1) In order to solve the above problems, an electric hydraulic pump of the present invention includes a pump main body having a pump case and sucking in and discharging hydraulic oil using a pump rotating element, an electric motor section including a motor case connected to the pump case and a motor rotor using a permanent magnet, a rotating shaft having one end to which the pump rotating element is fixed and the motor rotor fixed to the other end to coaxially rotate the pump rotating element and the motor rotor together, and an oil seal that seals a gap between an outer periphery of the rotating shaft and an inner periphery of the pump case at an end of the other end side of the pump case, wherein the rotating shaft is formed by coaxially connecting a pump side rotating shaft made of magnetic steel and to which the pump rotating element is fixed, and a motor side rotating shaft made of magnetic steel and to which the motor rotor is fixed, via a joint made of a non-magnetic member. The joint has a non-magnetic plating layer formed on the surface of the non-magnetic member. . (2) The plating layer of the non-magnetic material may be a chromium plating layer or a nickel plating layer. Specifically, the chromium plating layer or the nickel plating layer may be a hard chromium plating layer or a high to medium P type nickel plating layer. (3) A gap between the end of the pump-side rotating shaft and the end of the motor-side rotating shaft which face each other via the joint may be 10% or more of a shaft diameter of the end of the motor-side rotating shaft. (4) The joint may be a substantially short-shaft-shaped member having a first tip portion having a predetermined cross-section shape at the one end and a second tip portion having a predetermined cross-section shape at the other end, the pump-side rotating shaft having a first fitting hole drilled from an end face of the other end along a central axis and having a cross-section shaped to fit with the first tip portion to transmit axial rotation, and the motor-side rotating shaft having a second fitting hole drilled from an end face of the one end along a central axis and having a cross-section shaped to fit with the second tip portion to transmit axial rotation, and the rotating shaft may be formed by fitting the first tip portion into the first fitting hole and the second tip portion into the second fitting hole. (5)The pump side rotating shaft may have both ends protruding from the pump rotating element, and be rotatably supported by the pump case via a first bearing provided on the one end side of the pump rotating element and a second bearing provided on the other end side of the pump rotating element, and the first bearing and the second bearing may be provided on the one end side of the oil seal. (6) A pump main body having a pump case and sucking / discharging hydraulic oil using a pump rotating element, an electric motor section including a motor case coupled to the pump case and a motor rotor using a permanent magnet, a rotating shaft having one end to which the pump rotating element is fixed and the motor rotor fixed to the other end to rotate the pump rotating element and the motor rotor coaxially and integrally, and an oil seal for sealing a gap between an outer periphery of the rotating shaft and an inner periphery of the pump case at an end of the other end side of the pump case, the rotating shaft being made of a magnetic steel material and having the pump rotating element fixed thereto, and a motor side rotating shaft being made of a magnetic steel material and having the motor rotor fixed thereto, the rotating shaft being made of a non-magnetic steel material and having a non-magnetic steel material and ... the pump-side rotating shaft and the motor-side rotating shaft are coaxially coupled to each other via a joint made of a flexible member, the joint being a substantially short-shaft-shaped member having a first tip portion having a predetermined cross-section shape at the one end side and a second tip portion having a predetermined cross-section shape at the other end side, the pump-side rotating shaft having a first fitting hole drilled from an end face of the other end side along a central axis and having a cross-section shaped to fit with the first tip portion to transmit axial rotation, the motor-side rotating shaft having a second fitting hole drilled from an end face of the one end side along a central axis and having a cross-section shaped to fit with the second tip portion to transmit axial rotation, and the rotating shaft is formed by fitting the first tip portion into the first fitting hole and fitting the second tip portion into the second fitting hole, The pump side rotating shaft may have both sides protruding from the pump rotating element, and be rotatably supported by the pump case via a first bearing provided on the one end side of the pump rotating element and a second bearing provided on the other end side of the pump rotating element, and the second bearing may be arranged on the outer circumferential side of the pump side rotating shaft at a portion where the first tip portion is fitted into the first fitting hole. (7) The pump may be a variable displacement vane pump. Note that the electric hydraulic pump of the present invention is not limited to a variable displacement vane pump, and can be applied to any pump that draws in and discharges hydraulic oil using a pump rotating element, such as a fixed displacement vane pump, a variable displacement / fixed displacement piston pump, and a variable displacement / fixed displacement gear pump. Effect of the Invention

[0009] According to the electric hydraulic pump of the present invention, the rotating shaft is formed by coaxially connecting a pump-side rotating shaft made of magnetic steel to which the pump rotating element is fixed, and a motor-side rotating shaft made of magnetic steel to which the motor rotor is fixed, via a joint made of a non-magnetic material. With this configuration, it is possible to use a rotating shaft made of steel, which has excellent strength, workability, and cost, while blocking magnetization from the motor-side rotating shaft side due to the magnetic field from a permanent magnet with the joint made of a non-magnetic material. As a result, magnetization of the pump-side rotating shaft can be suppressed, thereby reducing adhesion of iron powder to the rotating shaft. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a vertical sectional view showing an electric hydraulic pump according to a first embodiment. [Diagram 2] 2 is a cross-sectional view of the electric hydraulic pump shown in FIG. 1 along the line AA. [Diagram 3] 2A, 2B, and 2C are enlarged partial views showing a joint portion of the electric hydraulic pump in FIG. 1, in which (a) is a longitudinal sectional view, (b) is a BB sectional view, and (c) is a CC sectional view. [Figure 4] FIG. 5 is a vertical sectional view showing an electric hydraulic pump according to a second embodiment. [Diagram 5] 5A, 5B, and 5C are enlarged partial views showing a joint portion of the electric hydraulic pump in FIG. 4, in which (a) is a longitudinal sectional view, (b) is a DD sectional view, and (c) is an EE sectional view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. (First embodiment) Fig. 1 is a vertical cross-sectional view showing an electric hydraulic pump 100 according to a first embodiment, and Fig. 2 is a cross-sectional view taken along line AA of Fig. 1. In the electric hydraulic pump 100 of this embodiment, a pump-side rotating shaft 131 and a motor-side rotating shaft 132 are coaxially joined via a joint 133, which is a member made of non-magnetic austenitic stainless steel (SUS303, 304, etc.), to form a rotating shaft 130.

[0012] The electric hydraulic pump 100 of this embodiment includes a pump main body 110, an electric motor unit 120, a rotating shaft 130, and an oil seal 140.

[0013] The pump body 110 has a pump case 111, and is a device that draws in and discharges hydraulic oil using a pump rotor 112, which is a pump rotating element, and in this embodiment, constitutes a variable displacement vane pump.

[0014] The pump case 111 is configured by combining a pump case body 111a and a pump lid 111b, and forms the outer shell of the pump body 110. An internal space 111c of the pump case 111 accommodates a pump rotor 112, a cam ring 113, and a pump side rotating shaft 131 described later.

[0015] As shown in Fig. 2, the pump rotor 112 is a substantially disk-shaped member. The pump rotor 112 is fixed to a pump-side rotating shaft 131 that passes through a central shaft hole 112a, and rotates integrally with the pump-side rotating shaft 131. A plurality of slits 112b are formed in the outer circumferential surface of the pump rotor 112 and are arranged at equal intervals in the circumferential direction. A vane 114 is housed in each slit 112b so as to be movable forward and backward in the radial direction.

[0016] The cam ring 113 is a substantially annular member and is disposed in the internal space 111c of the pump case 111 so as to surround the pump rotor 112. Both axial ends of the cam ring 113 and the pump rotor 112 are sealed by side plates 115, 116 (see FIG. 1) fixed to the internal space 111c. Therefore, when the pump rotor 112 rotates, the vane 114 comes into contact with the inner circumferential surface of the cam ring 113 by centrifugal force, and a plurality of compression chambers 117 are formed, each separated by a pair of adjacent vanes 114, 114, the pump rotor 112, the cam ring 113, and the side plates 115, 116.

[0017] Here, since the cam ring 113 is set at an eccentric position with respect to the pump rotor 112 and the pump-side rotating shaft 131, the distance between the outer periphery of the pump rotor 112 and the inner periphery of the cam ring 113 varies depending on the circumferential position. Therefore, when the pump rotor 112 rotates, the volume of each compression chamber 117 expands over a half circumference and contracts over a half circumference. At a position on the side plate 115 where the volume of the compression chamber 117 expands, an intake port 115a (see FIG. 1) is provided for drawing hydraulic oil into the compression chamber 117 from the outside. At a position where the volume of the compression chamber 117 contracts, an exhaust port 115b (see FIG. 1) is provided for discharging the hydraulic oil compressed in the compression chamber 117 to the outside. The amount of positional eccentricity of the cam ring 113 in the internal space 111c is adjusted by a maximum discharge amount adjustment screw 118, and the restraining force of the eccentricity is adjusted by a pressure adjustment screw 119.

[0018] As shown in FIG. 1, a through hole 111d through which the rotating shaft 130 passes is provided in the wall of the other end (the end on the electric motor unit 120 side) of the pump case body 111a, and a blind hole 111e for accommodating one end of the pump side rotating shaft 131 is provided in the center of the internal space 111c side of the pump lid 111b. A bush-shaped plain bearing 141 made of soft metal, which is a first bearing, is provided on the inner circumference of the blind hole 111e. Meanwhile, a plain bearing 142, which is a second bearing, is provided on the inner circumference of the through hole 111d. These bearings rotatably support the pump side rotating shaft 131. In addition, a ball bearing 143 for supporting the motor side rotating shaft 132, which will be described later, is provided on the other end side (the electric motor unit 120 side) of the plain bearing 142 of the through hole 111d.

[0019] 1, the electric motor unit 120 includes a motor case 121 coupled to the pump case 111, and a motor rotor 123 using a permanent magnet 123a. In this embodiment, an IPM motor is configured in which the permanent magnet 123a is embedded in the motor rotor 123.

[0020] The motor case 121 is configured by combining a motor case main body 121a and a motor lid 121b, and forms the outer shell of the electric motor unit 120. The stator 122, the motor rotor 123, and a motor-side rotating shaft 132 (described later) are housed in an internal space 121c of the motor case 121. The motor case main body 121a is a substantially cylindrical member with both ends open. The other end side (opposite the pump main body 110) of the motor case main body 121a is sealed with the motor lid 121b, and one end side (pump main body 110 side) is combined with the pump case main body 111a. As a result, the motor case 121 and the pump case 111 form an integrated casing. The motor lid 121b is provided with a bearing holder 121d on the internal space 121c side in the center thereof. A ball bearing 144 for supporting the other end side (the side opposite to the pump body 110) of the motor side rotating shaft 132 is fitted into the bearing holder 121d.

[0021] The stator 122 is held on the inner periphery of the motor case main body 121a. The stator 122 has comb-like teeth provided on the inner periphery of a stator core (not shown) that is annular when viewed in the axial direction, and windings (not shown) are wound around each of these teeth. The stator 122 generates a rotating magnetic field. The motor rotor 123 is a substantially disk-shaped or cylindrical member that is disposed on the inner periphery of the stator 122 with a predetermined air gap therebetween. Permanent magnets 123a are embedded in the motor rotor 123 at regular intervals in the circumferential direction near the outer periphery. The motor rotor 123 is fixed to a motor-side rotating shaft 132 that passes through a central shaft hole 123b, and is adapted to rotate integrally with the motor-side rotating shaft 132.

[0022] The rotating shaft 130 is a member that coaxially and integrally rotates the pump rotor (pump rotating element) 112 and the motor rotor 123. The pump rotor 112 is fixed to one end of the rotating shaft 130, and the motor rotor 123 is fixed to the other end. In this embodiment, the rotating shaft 130 is formed by coaxially connecting a pump side rotating shaft 131 and a motor side rotating shaft 132 via a joint 133, as shown in an enlarged view in FIG.

[0023] The pump side rotating shaft 131 is made of a magnetic steel material (e.g., SCM material). The pump side rotating shaft 131 is inserted and fitted into a shaft hole 112a of the pump rotor 112 (see FIG. 1) and is configured to rotate integrally with the pump rotor 112. The pump side rotating shaft 131 has a first fitting hole 131a at the other end side (electric motor side). The first fitting hole 131a has an involute spline shape in cross section and is drilled along the central axis from the end face of the other end side (electric motor side) of the pump side rotating shaft 131. The first fitting hole 131a is configured to fit into a first tip portion 133a of a joint 133 described later to transmit axial rotation. As shown in FIG. 1, the pump side rotating shaft 131 has protruding portions that protrude from the pump rotor 112 to one end side and the other end side (left and right direction in FIG. 1). The protruding portion on one end side is rotatably supported by a plain bearing 141 held by the pump lid 111b. The protruding portion on the other end side is rotatably supported by a plain bearing 142 provided in a through hole 111d of the pump case body 111a. The plain bearing 142 is disposed on the outer periphery of the pump side rotating shaft 131, at a fitting portion between the first tip end 133a of the joint 133 and the first fitting hole 131a. With this configuration, it is possible to reduce axial wobble of the pump side rotating shaft 131 at the joining portion between the pump side rotating shaft 131 and the joint 133, and to reduce vibration during rotation.

[0024] The motor-side rotating shaft 132 is made of a magnetic steel material (for example, SC material). The motor-side rotating shaft 132 is inserted and fitted into the shaft hole 123b of the motor rotor 123, and is configured to rotate integrally with the motor rotor 123. The motor-side rotating shaft 132 has a second fitting hole 132a at one end (pump body side). As shown in an enlarged view in FIG. 3, the second fitting hole 132a has a circular cross section with two chamfered sides, and is drilled along the central axis from the end face of the motor-side rotating shaft 132 at one end (pump body side). The second fitting hole 132a is configured to fit into a second tip portion 133b of a joint 133 described later to transmit axial rotation. As shown in FIG. 1, the motor-side rotating shaft 132 protrudes from the motor rotor 123 at one end and the other end (left and right directions in FIG. 1). The protruding portion on one end side is rotatably supported by a ball bearing 143 provided in a through hole 111d of the pump case body 111a. The protruding portion on the other end side is rotatably supported by a ball bearing 144 provided in the motor case 121. The tip portion of one end side (pump body side) of the motor side rotating shaft 132 protrudes from the ball bearing 143, and an oil seal 140 is in sliding contact with the outer periphery.

[0025] In this embodiment, the joint 133 is a substantially short-shaft-shaped member made of non-magnetic steel (austenitic stainless steel SUS303, SUS304, etc.). As shown in FIG. 3, the joint 133 has a first tip 133a having an involute spline shape in cross section at one end (pump body side), and a second tip 133b having a circular cross section with two chamfered sides at the other end (electric motor side). In this embodiment, the first tip 133a of the joint 133 is fitted into the first fitting hole 131a of the pump side rotating shaft 131, and the second tip 133b of the joint 133 is fitted into the second fitting hole 132a of the motor side rotating shaft 132. With this configuration, the pump side rotating shaft 131 and the motor side rotating shaft 132 are connected via the joint 133 to form the rotating shaft 130 of this embodiment. With this configuration, the rotating element side rotating shaft and the motor rotor side rotating shaft can be coaxially coupled via the joint with a simple structure.

[0026] In the rotating shaft 130 thus formed, a gap g between the end of the pump side rotating shaft 131 and the end of the motor side rotating shaft 132 which face each other via the joint 133 shown in Fig. 3(a) is set to 10% or more of the shaft diameter d of the end of the motor side rotating shaft 132. With this configuration, a sufficient magnetization blocking effect can be obtained between the motor side rotating shaft 132 and the pump side rotating shaft 131.

[0027] As shown in FIG. 1, the oil seal 140 seals the gap between the outer periphery of the rotating shaft 130 and the inner periphery of the pump case 111 at the other end side (electric motor section 120 side) of the pump case 111. The oil seal 140 thereby prevents hydraulic oil on the pump main body section 110 side from entering the electric motor section 120 side. In this embodiment, the oil seal 140 is made of rubber and formed into an annular shape with a substantially U-shaped cross section. The oil seal 140 is fitted into the inner periphery of the through hole 111d of the pump case main body 111a. The inner periphery side of the oil seal 140 is in sliding contact with the outer periphery side of the tip of one end side (pump main body side) of the motor side rotating shaft 132.

[0028] Next, the operation of the electric hydraulic pump 100 of this embodiment configured as described above will be described with reference to Figures 1 and 2. This operation is basically the same as that of a conventional variable displacement vane pump. That is, when the electric motor unit 120 is started, a rotating magnetic field is generated by the stator 122, and the motor rotor 123 rotates in accordance with the rotation of this magnetic field. At this time, the pump rotor 112 connected to the motor rotor 123 via the rotating shaft 130 also rotates.

[0029] As described above for the pump portion, when the pump rotor 112 rotates, the volume of each compression chamber 117 expands over half its circumference and contracts over the other half its circumference. At the position where the volume of the compression chamber 117 expands, hydraulic oil is sucked into the compression chamber 117 from the outside through the intake port 115a (see FIG. 1) of the side plate 115, while at the position where the volume of the compression chamber 117 contracts, the hydraulic oil compressed in the compression chamber 117 is discharged to the outside through the discharge port 115b (see FIG. 1) of the side plate 115. This allows the hydraulic oil to be pumped out.

[0030] Part of this hydraulic oil spreads inside the pump body 110 shown in FIG. 1 to lubricate the plain bearing 141 and the plain bearing 142. This hydraulic oil also comes into contact with the rotating shaft 130 (i.e., the joint 133 and the pump-side rotating shaft 131) on the one end side (pump body side) of the oil seal 140, so in the past there was a problem that iron powder in the hydraulic oil adhered to the rotating shaft 130. In particular, when using a motor rotor 123 equipped with a permanent magnet 123a, this problem was likely to occur because the rotating shaft 130 may be magnetized by the magnetic field of the permanent magnet 123a. In the electric hydraulic pump 100 of this embodiment, the joint 133 is made of non-magnetic steel, so magnetization from the motor-side rotating shaft 132 side due to the magnetic field from the permanent magnet 123a is blocked by this joint 133. As a result, the surfaces of the joint 133 and the pump-side rotating shaft 131 constituting the one end side (pump body side) of the oil seal 140 are less likely to be magnetized. This makes it possible to reduce the amount of iron powder that adheres to those parts of the rotating shaft 130 that come into contact with the hydraulic oil. In addition, iron powder is less likely to adhere to the pump side rotating shaft, so damage to these bearings can be reduced.

[0031] According to the configuration of the above embodiment, while using a rotating shaft made of steel, which is excellent in strength, workability, and cost, magnetization from the motor-side rotating shaft caused by the magnetic field from the permanent magnet can be blocked by a joint made of a non-magnetic material. As a result, magnetization of the pump-side rotating shaft can be suppressed, and iron powder adhering to the rotating shaft can be reduced. Also, adhesion of iron powder to the rotating shaft of a variable displacement vane pump can be reduced, thereby extending the pump life.

[0032] Second embodiment FIG. 4 is a vertical cross-sectional view showing an electric hydraulic pump according to a second embodiment of the present invention, and FIG. 5 is a partially enlarged view showing a joint portion thereof. In the electric hydraulic pump 200 of this embodiment, the joint 133 in the electric hydraulic pump 100 of the first embodiment has a non-magnetic plating layer formed on its surface. In this embodiment, a hard chrome plating layer 233c is provided as the non-magnetic plating layer in order to improve the wear resistance of the joint 233. However, the non-magnetic plating layer is not limited to the chrome plating layer 233c, and may be, for example, a high P to medium P type nickel plating layer. The other configuration of the electric hydraulic pump 200 is the same as that of the electric hydraulic pump 100 of the first embodiment, so the same components are denoted by the same reference numerals and detailed description thereof will be omitted.

[0033] As shown in Fig. 5, the shape of the joint 233 is the same as that of the joint 133 of the first embodiment shown in Fig. 3. As in the first embodiment, the pump side rotating shaft 131 and the motor side rotating shaft 132 are joined via the joint 233 to form the rotating shaft 230 of this embodiment. As in the first embodiment, the oil seal 140 is disposed at the tip of one end side (pump body side) of the motor side rotating shaft 132. Therefore, the joint 233 and the pump side rotating shaft 131 correspond to the one end side (pump body side) of the oil seal 140.

[0034] The operation of the electric hydraulic pump 200 of this embodiment is basically the same as that of the electric hydraulic pump 100 of the first embodiment. In this embodiment, too, magnetization from the motor-side rotating shaft 132 side due to the magnetic field from the permanent magnet 123a (see FIG. 4) is blocked by the joint 233. In addition, the chrome plating layer 233c applied to the joint 233 is also non-magnetic and has a magnetization blocking effect, making the surface of the pump-side rotating shaft 131 less likely to be magnetized. This makes it possible to reduce iron powder that adheres to these parts of the rotating shaft 230 that come into contact with the hydraulic oil. In addition to the above effects, the chrome plating layer 233c also has the effect of increasing the surface hardness of the joint 233 to improve wear resistance, and increasing oil film retention to improve lubrication characteristics.

[0035] Although the embodiment of the present invention has been described above, the present invention can be modified in various ways without departing from the gist of the invention.

[0036] For example, in the first and second embodiments, a variable displacement vane pump has been described as an example of the pump. However, the present invention is not limited to this, and the pump may be any pump that uses a pump rotating element. For example, a fixed displacement vane pump, a variable displacement / fixed piston pump, a variable displacement / fixed gear pump, etc. may be used.

[0037] In the first and second embodiments, an IPM motor is described as an example of the motor, but the present invention is not limited to this, and the motor may be any motor that uses a permanent magnet, such as an SPM motor.

[0038] In the first and second embodiments, the configuration of the joint 133, 233 is described as a configuration in which the tip portions on each side of the joint are fitted into the fitting holes of the respective shafts, but the present invention is not limited to this. For example, the tip portions of each shaft may be fitted into the fitting holes on each side of the joint, or the tip portion of one shaft may be fitted into the fitting hole on one side of the joint, and the tip portion of the other side of the joint may be fitted into the fitting hole of the other shaft. [Explanation of symbols]

[0039] 100, 200 Electric hydraulic pump 110 Pump body 111 Pump case 111a Pump case body 111b Pump cover 111c interior space 111d Through hole 111e Blind hole 112 Pump rotor 112a Shaft hole 112b Slit 113 Cam Ring 114 Vane 115 Side Plate 115a Inlet 115b Discharge port 116 Side Plate 117 Compression Chamber 118 Maximum discharge volume adjustment screw 119 Pressure adjustment screw 120 Electric motor section 121 Motor case 121a Motor case body 121b Motor cover 121c interior space 121d Bearing holder 122 Stator 123 Motor rotor 123a Permanent magnet 123b Shaft hole 130, 230 Rotation axis 131 Pump side rotating shaft 131a First fitting hole 132 Motor side rotating shaft 132a Second fitting hole 133, 233 Joint 133a First tip 133b Second tip 140 Oil seal 141, 142 Plain bearings 143, 144 Ball bearings 233c chrome plating layer

Claims

1. A pump main body having a pump case and sucking and discharging hydraulic oil using a pump rotating element; an electric motor section including a motor case coupled to the pump case and a motor rotor using a permanent magnet; a rotating shaft having one end side to which the pump rotating element is fixed and the other end side to which the motor rotor is fixed, so as to coaxially rotate the pump rotating element and the motor rotor integrally; an oil seal that seals a gap between an outer periphery of the rotating shaft and an inner periphery of the pump case at an end portion on the other end side of the pump case, The rotating shaft is a pump-side rotating shaft made of magnetic steel and having the pump rotating element fixed thereto, and a motor-side rotating shaft made of magnetic steel and having the motor rotor fixed thereto, which are coaxially connected via a joint made of a non-magnetic member; 13. The electric hydraulic pump, wherein the joint has a non-magnetic plating layer formed on a surface of the non-magnetic member.

2. 2. The electric hydraulic pump according to claim 1, wherein the non-magnetic plating layer is a chrome plating layer or a nickel plating layer.

3. 2. The electric hydraulic pump according to claim 1, wherein a gap between the end of the pump-side rotating shaft and the end of the motor-side rotating shaft which face each other via the joint is 10% or more of a shaft diameter of the end of the motor-side rotating shaft.

4. the joint is a substantially short-shaft-shaped member having a first tip portion having a predetermined cross-sectional shape at the one end side and a second tip portion having a predetermined cross-sectional shape at the other end side; the pump-side rotating shaft has a first fitting hole drilled along a central axis from an end face on the other end side and having a cross section shaped to fit into the first tip portion to transmit axial rotation, the motor-side rotating shaft has a second fitting hole drilled along a central axis from an end face on the one end side and having a cross section shaped to fit into the second tip portion to transmit axial rotation, 2. The electric hydraulic pump according to claim 1, wherein the rotating shaft is formed by fitting the first tip end portion into the first fitting hole and fitting the second tip end portion into the second fitting hole.

5. the pump-side rotating shaft has both ends protruding from the pump rotating element, and is rotatably supported by the pump case via a first bearing provided on the one end side of the pump rotating element and a second bearing provided on the other end side of the pump rotating element; 2. The electric hydraulic pump according to claim 1, wherein the first bearing and the second bearing are provided closer to the one end than the oil seal.

6. A pump body having a pump case and sucking and discharging hydraulic oil using a pump rotating element; an electric motor section including a motor case coupled to the pump case and a motor rotor using a permanent magnet; a rotating shaft having one end side to which the pump rotating element is fixed and the other end side to which the motor rotor is fixed, so as to coaxially rotate the pump rotating element and the motor rotor integrally; an oil seal that seals a gap between an outer periphery of the rotating shaft and an inner periphery of the pump case at an end portion on the other end side of the pump case, The rotating shaft is a pump-side rotating shaft made of magnetic steel and having the pump rotating element fixed thereto, and a motor-side rotating shaft made of magnetic steel and having the motor rotor fixed thereto, which are coaxially connected via a joint made of a non-magnetic member; the joint is a substantially short-shaft-shaped member having a first tip portion having a predetermined cross-sectional shape at the one end side and a second tip portion having a predetermined cross-sectional shape at the other end side; the pump-side rotating shaft has a first fitting hole drilled along a central axis from an end face on the other end side and having a cross section shaped to fit into the first tip portion to transmit axial rotation, the motor-side rotating shaft has a second fitting hole drilled along a central axis from an end face on the one end side and having a cross section shaped to fit into the second tip portion to transmit axial rotation, the rotating shaft is formed by fitting the first tip end portion into the first fitting hole and fitting the second tip end portion into the second fitting hole, the pump-side rotating shaft has both ends protruding from the pump rotating element, and is rotatably supported by the pump case via a first bearing provided on the one end side of the pump rotating element and a second bearing provided on the other end side of the pump rotating element; the second bearing is disposed on an outer circumferential side of the pump-side rotating shaft at a portion where the first tip portion is fitted into the first fitting hole.

7. 2. The electric hydraulic pump according to claim 1, wherein the pump body is a variable displacement vane pump.

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