Hydraulic Unit

Abstract

To provide a hydraulic unit for reducing noise by suppressing resonance of vibration which is generated by the rotation drive of a motor and a hydraulic pump, with the vibration of a top plate.SOLUTION: An upper part opening of an oil tank storing working oil is closed with a top plate 4. On an upper face 4A of the top plate 4, a motor 6 and a hydraulic pump 7 for sucking / discharging working oil stored in the oil tank are placed with an axial center 6L set in the horizontal direction. On the top plate 4, a weight 19 having a weight is provided at a downward position in the vertical direction of the motor 6. The weight of weight 19 operates on the top plate 4 at its position almost the same as that of the axial center 6L of the motor 6 in the horizontal direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a hydraulic unit in which an electric motor and a hydraulic pump are mounted on an oil tank. [Background technology]

[0002] In this type of hydraulic unit, the upper opening of the oil tank that stores the hydraulic oil is closed with a top plate, a stand is fixed to the top surface of the top plate via vibration-proof rubber, an electric motor with an integrally connected pump is fixed to the top surface of the stand, and sound-absorbing material is attached to the top surface of the top plate. The sound-absorbing material absorbs radiated and reflected sounds from the electric motor and hydraulic pump, reducing noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-42501 Summary of the Invention [Problem to be solved by the invention]

[0004] However, such conventional hydraulic units have a problem in that the vibration frequency generated by the rotational drive of the electric motor and hydraulic pump is close to the natural frequency of the top plate, causing resonance, and therefore it is still not possible to achieve satisfactory noise reduction.

[0005] An object of the present invention is to provide a hydraulic unit that reduces noise by suppressing resonance between the vibrations generated by the rotational drive of an electric motor and a hydraulic pump and the vibrations of the top plate. [Means for solving the problem]

[0006] In order to achieve this object, the present invention takes the following measures: The top opening of the oil tank, which stores hydraulic oil inside, is closed with a top plate, and an electric motor and a hydraulic pump that is driven by the electric motor to suck and discharge the hydraulic oil stored in the oil tank are mounted on the top surface of the top plate with their axes in the horizontal direction, and a weight having a weight is attached to the top plate at a position vertically below the electric motor. The back side opposite to the top side Established in The weight is provided with a center position on the top plate at a position substantially the same as the axis of the motor in the horizontal direction. This hydraulic unit is characterized in that the weight of the weight acts on the top plate at approximately the same position in the horizontal direction as the axis of the electric motor.

[0007] The hydraulic unit is characterized in that the upper opening of an oil tank which stores hydraulic oil inside is closed with a top plate, and an electric motor and a hydraulic pump which is rotated by the electric motor to draw in and discharge the hydraulic oil stored in the oil tank are placed on the upper surface of the top plate with their axis horizontal, and a weight having a weight is attached to the back side of the top plate opposite the top surface, vertically below the electric motor, with two weights provided, positioned symmetrically in the horizontal direction across the axis of the electric motor, and the weight of the weight acts at approximately the same position on the top plate in the horizontal direction as the axis of the electric motor. Effect of the Invention

[0008] As described above in detail, claim 1 and claim 2 In the invention described in the above, a weight having a weight is provided on the top plate below the electric motor in the vertical direction, and the weight of the weight acts on the top plate at approximately the same position in the horizontal direction as the axis of the electric motor. Therefore, the natural frequency of the top plate can be set without being shifted from and approximated to the vibration frequency generated by the rotational drive of the electric motor and hydraulic pump, so that resonance between the vibration generated by the rotational drive of the electric motor and hydraulic pump and the vibration of the top plate can be suppressed, and noise can be reduced.

[0009] Also, Claim 1 and In the invention described in claim 2, the weight is attached to the back side of the top plate, which is opposite to the top surface. Therefore, the weight is inside the oil tank and is not exposed to the outside, so it does not interfere with the electric motor, etc., that is placed on the top surface of the top plate.

[0010] Also, Claim 1 In the invention described in the above, the center position of the weight is located at approximately the same position on the top plate as the axis of the motor in the horizontal direction. Therefore, the weight can be arranged as a single unit in one place.

[0011] Also, Claim 2 In the invention described in the above, two weights are provided, and the two weights are provided at symmetrical positions in the horizontal direction with respect to the axis of the motor. Therefore, the two weights do not need to be provided at approximately the same position in the horizontal direction with respect to the axis of the motor, and the degree of freedom in the position where the weights are provided can be increased. [Brief description of the drawings]

[0012] [Figure 1] 1 is a front view, partly in section, of a hydraulic unit showing one embodiment of the present invention; [Diagram 2] FIG. 2 is a plan view taken along the arrow A in FIG. [Diagram 3] FIG. 11 is a plan view of a hydraulic unit according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1 and FIG. 2, 1 is a hydraulic oil storage device. oil The oil tank 1 is formed in a roughly rectangular parallelepiped shape with an opening at the top. The oil tank 1 is provided with a seal member 3 on the periphery of the top opening. 4 is a top plate that closes the top opening of the oil tank 1, and is placed on the seal member 3 and detachably attached to the oil tank 1 with multiple bolts 5 to seal the inside of the oil tank 1. The periphery of the top plate 4 is bent downward in the vertical direction (downward parallel to the paper surface in Fig. 1, and in the depth direction perpendicular to the paper surface in Fig. 2). 6 is an electric motor that drives and rotates a hydraulic pump 7, and is placed and fixed on the upper surface 4A of the top plate 4 with its axis 6L in the horizontal direction (parallel to the paper surface in Fig. 2) via four vibration-proof members 8. Each vibration-proof member 8 is cylindrical and made of rubber, and is arranged diagonally below the electric motor 6. The hydraulic pump 7 is fixed concentrically to one side of the electric motor 6 on the top plate 4, and is provided integrally with the electric motor 6. The hydraulic pump 7 is driven by the rotation of the electric motor 6 to draw hydraulic oil stored in the oil tank 1 through a suction passage 9 and discharge it to a discharge passage 10 .

[0014] Reference numeral 11 denotes an oil level gauge for visually checking the amount of hydraulic oil stored from the outside, and is disposed above one side of the oil tank 1. Reference numeral 12 denotes a plug member for detachably closing the outlet for discharging the stored hydraulic oil, and is disposed below one side of the oil tank 1. Reference numeral 13 denotes an oil inlet / air breather for injecting hydraulic oil into the oil tank 1, and is disposed on the top plate 4 of the oil tank 1. Reference numeral 14 denotes a cooler for cooling the drain of the hydraulic pump 4, and is disposed upright on the top plate 4 of the oil tank 1 facing the other side opposite to the one side of the electric motor 6 to which the hydraulic pump 7 is fixed. The cooler cools the drain introduced from the drain inlet pipe 15 with the wind generated by a cooling fan (not shown) of the electric motor 6, and the cooled drain is returned to the oil tank 1 through the drain outlet pipe 16. Reference numeral 17 denotes four hook members disposed on the four corners of the top plate 4, and is used when lifting and moving the hydraulic unit.

[0015] Reference numeral 18 denotes a rectangular, thin vibration-damping sheet made of rubber and attached to the upper surface 4A of the top plate 4 to suppress vibration of the top plate 4. The vibration-damping sheet 18 is located below the motor 4, with most of the sheet positioned inside the four vibration-proof members 8, and both ends extending slightly outward from the vibration-proof members 8. Reference numeral 19 denotes a weight having a weight of about 400 grams, which is attached by welding to the back surface 4B of the top plate 4 opposite the upper surface 4A, below the motor 6 in the vertical direction. The weight 19 has a center position C on the top plate 4 at approximately the same position in the horizontal direction as the axis 6L of the motor 6, and the weight of the weight 19 acts on the top plate 4 at approximately the same position in the horizontal direction as the axis 6L of the motor 6. The weight 19 is located between one end 18A of the vibration-damping sheet 18 and the cooler 14.

[0016] Next, the operation of this configuration will be described. When the hydraulic pump 7 is driven to rotate by the electric motor 6, the hydraulic pump 7 draws hydraulic oil stored in the oil tank 1 through the suction passage 9 and discharges it to the discharge passage 10. This discharged hydraulic oil is supplied to an actuator (not shown). Return oil from the actuator flows through a return passage (not shown) and returns to the oil tank 1.

[0017] At this time, vibrations generated by the rotational drive of the electric motor 6 and hydraulic pump 7 are prevented from being transmitted to the top plate 4 of the oil tank 1 by vibration-proofing members 8. Furthermore, vibrations of the top plate 4 are suppressed by a vibration-damping sheet 18. The drain of the hydraulic pump 7 is cooled by a cooler 14 and returned to the oil tank 1 through a drain outlet pipe 16.

[0018] With this operation, a weight 19 having a weight is attached to the tabletop 4 vertically below the electric motor 6, and the weight of the weight 19 acts on the tabletop 4 at approximately the same position in the horizontal direction as the axis 6L of the electric motor 6. Therefore, the natural frequency of the tabletop 4 can be set without being shifted from and approximated to the vibration frequency generated by the rotational drive of the electric motor 6 and hydraulic pump 7, so that resonance between the vibration generated by the rotational drive of the electric motor 6 and hydraulic pump 7 and the vibration of the tabletop 4 can be suppressed, thereby reducing noise.

[0019] In addition, the weight 19 is attached to the back surface 4B opposite to the top surface 4A of the top plate 4. Therefore, the weight 19 is inside the oil tank 1 and is not exposed to the outside, so it does not interfere with the electric motor 6 and the like placed on the top surface 4A of the top plate 4.

[0020] Furthermore, the center position C of the weight 19 is located at approximately the same position in the horizontal direction on the top plate 4 as the axis 6L of the electric motor 6. Therefore, the weight 19 can be disposed as a single unit in one place.

[0021] FIG. 3 shows another embodiment of the present invention. The same parts as those in the first embodiment are given the same reference numerals and their explanation is omitted, and only the different parts will be explained. Two weights 19A and 19B are provided and attached by welding to the rear surface 4B of the top plate 4 at a position vertically below the electric motor 6. The two weights 19A and 19B are provided at symmetrical positions in the horizontal direction across the axis 6L of the electric motor 6.

[0022] In operation, the electric motor 6 rotates and drives the hydraulic pump 7, which then draws in and discharges hydraulic oil stored in the oil tank 1. The discharged hydraulic oil is supplied to an actuator (not shown), and the return oil from the actuator flows through a return flow path (not shown) and returns to the oil tank 1.

[0023] With this operation, weights 19A and 19B having weights are provided on the tabletop 4 vertically below the electric motor 6, and the weights of the weights 19A and 19B act on the tabletop 4 at substantially the same position in the horizontal direction as the axis 6L of the electric motor 6. Therefore, as in the first embodiment, the natural frequency of the tabletop 4 can be set without being shifted from and approximated to the vibration frequency generated by the rotational driving of the electric motor 6 and the hydraulic pump 7, so that resonance between the vibration generated by the rotational driving of the electric motor 6 and the hydraulic pump 7 and the vibration of the tabletop 4 can be suppressed, thereby reducing noise.

[0024] Weights 19A and 19B are attached to the back surface 4B opposite to the top surface 4A of the top plate 4. Therefore, weights 19A and 19B are inside the oil tank 1 and are not exposed to the outside, so they do not interfere with the electric motor 6 and the like placed on the top surface 4A of the top plate 4, as in the first embodiment.

[0025] Furthermore, two weights 19A and 19B are provided, and the two weights 19A and 19B are provided at horizontally symmetrical positions across the axis 6L of the electric motor 6. Therefore, the two weights 19A and 19B do not need to be provided at approximately the same position as the axis 6L of the electric motor 6, and the degree of freedom in the positions at which the weights 19A and 19B are provided can be increased.

[0026] In the above-described embodiments, the vibration-damping sheet 18 is attached to the upper surface 4A of the tabletop 4, but the vibration-damping sheet need not be provided as necessary. In this case, the weight may be provided at the center of the four vibration-damping members arranged diagonally. In addition, the hydraulic pump 7 is fixed concentrically to one side of the electric motor 6 and provided integrally with the electric motor 6, but it goes without saying that the input shaft of the hydraulic pump and the output shaft of the electric motor may be connected by a coupling, and the hydraulic pump and the electric motor may be provided separately. [Explanation of symbols]

[0027] 1: Oil tank 4: Tabletop 4A:Top surface 6: Electric motor 6L: Axial center 7: Hydraulic pump 19, 19A, 19B: Weights

Claims

1. A hydraulic unit comprising: an oil tank having an upper opening which stores hydraulic oil therein, and a top plate which covers the upper opening of the oil tank; an electric motor and a hydraulic pump which is rotated by the electric motor and which draws in and discharges hydraulic oil stored in the oil tank, and which are mounted on the upper surface of the top plate with their axis horizontal; and a weight having a weight is mounted on the back surface of the top plate, opposite the top surface, vertically below the electric motor, with the center of the weight positioned approximately horizontally on the top plate at approximately the same position as the axis of the electric motor, and the weight of the weight acts on the top plate at approximately the same position in the horizontal direction as the axis of the electric motor.

2. A hydraulic unit characterized in that the upper opening of an oil tank which stores hydraulic oil therein is closed with a top plate, and an electric motor and a hydraulic pump which is rotated and driven by the electric motor to draw in and discharge the hydraulic oil stored in the oil tank are placed on the upper surface of the top plate with their axis horizontal, and a weight having a weight is attached to the back side of the top plate opposite the top surface vertically below the electric motor, two weights are provided, and are positioned symmetrically horizontally through the axis of the electric motor, so that the weight of the weight acts at approximately the same position horizontally as the axis of the electric motor on the top plate.

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