Rotation drive system

Abstract

To provide a rotation drive system capable of supplying work fluid for releasing a brake and lubrication oil for a speed reducer from one hydraulic source and capable of cooling an electric motor while maintaining cleanliness of the lubrication oil.SOLUTION: A rotation drive system 100 includes: a brake piston 140 that comes into frictional contact with brake disks 138a, 138b fixed to a shaft 126 of an electric motor 102; a brake spring 142 that energizes the brake piston toward the brake disks; a brake release port 110 that supplies work fluid for releasing a brake from a hydraulic source 112 to a brake chamber 152; a communication hole 156 communicating with the brake chamber side to the electric motor side of the brake piston; a discharge port 122 provided in a housing 120 of the electric motor to discharge the work fluid that has passed from the brake chamber through inside of the electric motor via the communication hole; and a supply passage 118 that is formed between the brake piston and the brake disks to supply the work fluid to a speed reducer 104 when the brake is released.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a rotary drive system including a motor with a reducer. [Background technology]

[0002] As an example, a rotary drive system equipped with an electric motor with a reducer is used in construction machinery such as a hydraulic excavator (for example, Patent Document 1). Patent Document 1 describes a hydraulic excavator equipped with a rotary drive system that rotates an upper rotating body relative to a lower traveling body.

[0003] This rotary drive system includes an electric motor, a reducer that slows down the rotation of the electric motor, a hydraulic pump, and a lubricating oil pump. The hydraulic pump supplies pressurized oil (hydraulic oil) that releases the brake when the electric motor is operating. The lubricating oil pump supplies lubricating oil to the electric motor to maintain its cooling and lubrication properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-154101 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the rotary drive system of Patent Document 1 has two hydraulic pressure sources: a lubricating oil pump that supplies lubricating oil to the reducer, and a hydraulic pump that discharges pressurized oil for releasing the brake, and therefore requires two oil passages.

[0006] Furthermore, in the rotary drive system of Patent Document 1, the lubricating oil stored in a reservoir inside the reducer is also used to cool the electric motor. Because this lubricating oil continues to circulate inside the device, it must be replaced periodically to maintain cleanliness. However, in relatively small hydraulic excavators known as mini-excavators, for example, the rotary drive system is located below the operator's seat installed inside the cab of the upper rotating body. For this reason, when replacing the lubricating oil in the rotary drive system of a mini-excavator, it is necessary to remove the floor frame inside the cab, which is time-consuming.

[0007] In view of these problems, the present invention aims to provide a rotary drive system that can supply hydraulic oil for releasing the brake and lubricating oil for the reducer from a single hydraulic source, and that can cool the electric motor while maintaining the cleanliness of the lubricating oil. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, a typical configuration of a rotary drive system according to the present invention includes an electric motor, a reducer that decelerates the rotation of the electric motor, and a brake mechanism that is arranged between the electric motor and the reducer and stops the rotation of the reducer, wherein the brake mechanism includes a brake casing, a brake disc fixed to the shaft of the electric motor, a brake piston that is in frictional contact with the brake disc, a brake spring that urges the brake piston toward the brake disc, a brake chamber defined by the brake casing and the brake piston, a brake release port provided in the brake casing that supplies hydraulic oil from an external hydraulic source to the brake chamber so as to move the brake piston toward the electric motor against the urging force of the brake spring and separate it from the brake disc, a communication hole formed in the brake piston that communicates from the brake chamber side to the electric motor side, a discharge port provided in the housing of the electric motor that discharges hydraulic oil that has passed through the electric motor from the brake chamber through the communication hole of the brake piston, and a supply path that is formed between the brake piston and the brake disc when the brake piston moves toward the electric motor and supplies the hydraulic oil supplied to the brake chamber to the reducer.

[0009] It is preferable that a slit is formed in the end face of the brake piston on the electric motor side, and that the slit communicates from the communication hole to the edge of the end face on the electric motor side.

[0010] The electric motor preferably has a stator fixed to the housing and a rotor that rotates with the shaft when current is applied, and the hydraulic oil passes through the gap between the rotor and the stator, passes through the motor, and is discharged from the discharge port. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a rotary drive system that can supply hydraulic oil for releasing the brake and lubricating oil for the reducer from a single hydraulic source, and can cool the electric motor while maintaining the cleanliness of the lubricating oil. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an overall configuration diagram of a rotation drive system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing details of the rotary drive system of FIG. 1. [Figure 3] FIG. 3 is an enlarged view of a main part of the rotation drive system of FIG. 2. [Figure 4] 4 shows a brake piston of the rotary drive system of FIG. 3. FIG. [Figure 5] 3 is a diagram showing the flow of hydraulic oil supplied to the rotary drive system of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0014] 1 is an overall configuration diagram of a rotary drive system 100 according to an embodiment of the present invention. The rotary drive system 100 is a system used in construction machinery such as a hydraulic excavator, and includes an electric motor 102, a reducer 104 (RED. in the figure stands for reduction) that reduces the rotation speed of the electric motor 102, and a brake mechanism 106. The electric motor 102 is a rotary actuator such as a hydraulic motor or water hydraulic motor, and its driving force may be hydraulic or other existing power sources.

[0015] The brake mechanism 106 prevents unintended rotation of the electric motor 102 by stopping the rotation of the reducer 104 when the operation of the electric motor 102 is stopped. The brake mechanism 106 is also connected to an external hydraulic source 112 via a brake release port 110 provided in a brake casing 108 (see FIG. 2).

[0016] The hydraulic source 112 draws hydraulic oil from a hydraulic oil tank 116 that has passed through a strainer 114 and supplies it to the brake release port 110. The brake release port 110 also supplies hydraulic oil from the hydraulic source 112 to the brake mechanism 106, which releases the brake of the brake mechanism 106 when the electric motor 102 is operating.

[0017] The hydraulic oil supplied to the brake mechanism 106 from the external hydraulic source 112 is not only supplied through the brake mechanism 106 into the electric motor 102 to cool the electric motor 102, but also supplied to the reducer 104 as lubricating oil via a supply path 118, as will be described in detail later. The hydraulic oil supplied to the electric motor 102 is also discharged into a drain pan 124 through a discharge port 122 provided in a housing 120 (see FIG. 2) of the electric motor 102.

[0018] Fig. 2 is a diagram showing details of rotational drive system 100 in Fig. 1. Fig. 3 is an enlarged view of a main part of rotational drive system 100 in Fig. 2. Fig. 3 is an enlarged view of the area surrounded by dotted line A in Fig. 2.

[0019] As shown in FIG. 2, the rotary drive system 100 integrates an electric motor 102, a reducer 104, and a brake mechanism 106, with the brake mechanism 106 being disposed between the electric motor 102 and the reducer 104.

[0020] The electric motor 102 has a shaft 126, a rotor 128, and a stator 130. The shaft 126 is supported by bearings 132 (see FIG. 3 ), passes through a flange 134 of the electric motor 102, and extends into a brake casing 108 of the brake mechanism 106. When a current is applied to the electric motor 102, the interaction between the rotor 128 and the stator 130 causes the shaft 126 to rotate together with the rotor 128.

[0021] 3, two brake discs 138a and 138b, a brake piston 140, and a brake spring 142, which are arranged inside the brake casing 108. The disc support 136 is a disk-shaped member, and is fitted onto the shaft 126 of the electric motor 102.

[0022] The brake discs 138a, 138b are annular members that fit into the disc support portion 136. An annular holding member 144a is disposed on the brake piston 140 side of the brake disc 138a. An annular holding member 144b is disposed between the brake discs 138a, 138b. The holding members 144a, 144b are fixed by fitting into grooves formed in the brake casing 108.

[0023] Friction plates 139a and 139b are bonded to the top and bottom ends of brake discs 138a and 138b, respectively. As a result, holding member 144a is in contact with the upper friction plate 139a of brake disc 138a and brake piston 140, as shown in Figure 3. Holding member 144b is in contact with the lower friction plate 139a of brake disc 138a and also in contact with the upper friction plate 139b of brake disc 138b.

[0024] 3, the brake spring 142 is accommodated in the accommodation portion 146 of the brake piston 140 and is disposed between the flange 134 of the electric motor 102 and the brake piston 140. The brake piston 140 is urged toward the brake discs 138a, 138b by the urging force indicated by the arrow B of the brake spring 142 in FIG.

[0025] When the retaining member 144a is pressed against the brake piston 140, the brake discs 138a, 138b, including the friction plates 139a, 139b, move integrally with the retaining members 144a, 144b. At this time, the brake discs 138a, 138b and the retaining members 144a, 144b all bend and come into frictional contact. Then, the friction plate 139b of the brake disc 138b comes into contact with the opposing surface 150 of the brake casing 108, and the brake discs 138a, 138b become immobile due to the frictional force with the brake casing 108. In this way, the brake mechanism 106 enters a braking state in which the disc support portion 136 cannot rotate, and rotation of the shaft 126 can be prevented when the electric motor 102 is stopped.

[0026] The brake mechanism 106 also has a brake chamber 152 defined by the brake casing 108 and brake piston 140 shown in Figure 3. The brake chamber 152 is located at the end of a brake release pressure oil passage 154 that continues to the brake release port 110 (see Figure 2), and is a space where the hydraulic pressure of the working oil acts on the brake piston 140.

[0027] That is, hydraulic oil is supplied to brake chamber 152 from brake release port 110 through brake release pressure oil passage 154. The hydraulic oil supplied to brake chamber 152 generates a hydraulic force indicated by arrow C against the biasing force indicated by arrow B of brake spring 142. The hydraulic oil then moves brake piston 140 toward electric motor 102, causing brake piston 140 to move away from brake discs 138a, 138b. In brake mechanism 106, when brake piston 140 moves away from brake discs 138a, 138b due to the hydraulic force of the hydraulic oil, disc support portion 136 fitted to shaft 126 enters a brake-released state in which it can rotate.

[0028] Furthermore, when the brake piston 140 moves toward the electric motor 102 (i.e., when the brake is released), a gap is formed between the friction plates 139a, 139b of the brake discs 138a, 138b and the retaining members 144a, 144b. This gap functions as a supply path 118 (see FIG. 1) that supplies hydraulic oil to the reducer 104.

[0029] Figure 4 is a diagram showing brake piston 140 of rotary drive system 100 of Figure 3. Figure 4(a) is a top view of brake piston 140, showing a state in which brake spring 142 is housed in housing portion 146 of brake piston 140. Figure 4(b) is a DD cross-sectional view of brake piston 140 of Figure 4(a).

[0030] Brake piston 140 has a communication hole 156 and a slit 158. As shown in FIG. 3, communication hole 156 communicates from the brake chamber 152 side to the electric motor 102 side. Also, a slit 158 ​​is formed in an end face 160 of brake piston 140 on the electric motor 102 side. As shown in FIG. 4(a), slit 158 ​​communicates from communication hole 156 to an edge 162 of end face 160 on the housing portion 146 side.

[0031] 2, the reducer 104 has an output shaft 164, and a first-stage planetary gear mechanism 170 and a second-stage planetary gear mechanism 172 disposed in an internal space 168 of a reducer casing 166. The reducer 104 reduces the rotation (output) of the shaft 126 of the electric motor 102 by the first-stage planetary gear mechanism 170 and the second-stage planetary gear mechanism 172, and outputs the reduced rotation from the output shaft 164.

[0032] Fig. 5 is a diagram showing the flow of hydraulic oil supplied to the rotary drive system 100 of Fig. 2. In the figure, the hydraulic oil is shown by hatching, and the flow of the hydraulic oil is indicated by arrows.

[0033] In the rotary drive system 100, when hydraulic oil is supplied from the external hydraulic source 112 to the brake release port 110 (arrow E) while the electric motor 102 is operating, the hydraulic oil is supplied to the brake chamber 152 through the brake release oil passage 154 shown in Figure 3. When the hydraulic oil is supplied to the brake chamber 152, as described above, a hydraulic force shown by arrow C is generated against the biasing force of the brake spring 142 shown by arrow B in Figure 3, and the brake piston 140 moves toward the electric motor 102, thereby releasing the brake.

[0034] The hydraulic oil supplied to the brake chamber 152 passes through a communication hole 156 of the brake piston 140 shown in Fig. 3 and reaches an end face 160 on the electric motor 102 side (see arrow F in Fig. 5). The hydraulic oil then passes through a slit 158 ​​that communicates with an edge 162 of the end face 160 of the brake piston 140 (see Fig. 4(a)) and reaches an internal space 174 of the brake mechanism 106 shown in Fig. 5.

[0035] In other words, even if the brake piston 140 moves toward the electric motor 102 due to the hydraulic oil supplied to the brake chamber 152 and the end face 160 of the brake piston 140 is blocked by the flange 134 of the electric motor 102, the slit 158 ​​formed in the end face 160 ensures that the hydraulic oil is supplied to the internal space 174 of the brake mechanism 106.

[0036] The hydraulic oil supplied to the internal space 174 of the brake mechanism 106 then passes through the gap between the flange 134 and the shaft 126 of the electric motor 102 (arrow G), and further passes through the gap between the rotor 128 and the stator 130 (arrow H), before reaching the internal space 176 of the electric motor 102.

[0037] Subsequently, the hydraulic oil that reaches the internal space 176 of the electric motor 102 passes through a discharge port 122 (arrow J) provided in the housing 120 of the electric motor 102 and is discharged into a drain pan 124 (see FIG. 1). The hydraulic oil passing through the electric motor 102 in this manner can cool the electric motor 102.

[0038] Furthermore, when the brake piston 140 moves toward the electric motor 102 and the brake is released, the hydraulic oil supplied to the brake chamber 152 passes through the supply path 118 (see FIGS. 1 and 3) formed by the inner diameter portions 147a, 147b of the holding members 144a, 144b shown in FIG. 3 and the gaps between the fitting portions of the disc support portion 136 and the brake discs 138a, 138b (see arrow K in FIG. 5), and reaches the internal space 168 of the reducer casing 166. In this way, the hydraulic oil is supplied as lubricating oil into the reducer 104.

[0039] Therefore, in the rotary drive system 100, the hydraulic oil for releasing the brake of the brake mechanism 106 and the lubricating oil for the reducer 104 can be supplied from a single hydraulic source 112, and the hydraulic oil can also be used to cool the electric motor 102.

[0040] Furthermore, hydraulic oil is supplied to brake chamber 152 each time the brake is released and is discharged from discharge port 122 provided in housing 120 of electric motor 102. Therefore, in rotary drive system 100, hydraulic oil is not an internally circulating lubricant, so there is no need to take the trouble of replacing the (internally circulating) lubricant, and the cleanliness of the lubricant can be maintained.

[0041] In rotary drive system 100, slit 158 ​​is formed in end face 160 of brake piston 140 in consideration of the possibility that end face 160 of brake piston 140 may be blocked by flange 134 of electric motor 102 when the brake is released, but this is not limiting. As an example, instead of slit 158, a step may be appropriately provided in end face 160 of brake piston 140 to form a gap, thereby allowing hydraulic oil to be supplied to internal space 174 of brake mechanism 106.

[0042] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention. [Industrial Applicability]

[0043] The present invention can be used as a rotary drive system including a motor with a reducer. [Explanation of symbols]

[0044] 100...rotary drive system, 102...electric motor, 104...reduction gear, 106...brake mechanism, 108...brake casing, 110...brake release port, 112...hydraulic source, 114...strainer, 116...hydraulic oil tank, 118...supply path, 120...electric motor housing, 122...discharge port, 124...drain pan, 126...shaft, 128...rotor, 130...stator, 132...bearing, 134...electric motor flange, 136...disc support, 138a, 138b...brake disc, 139a, 139b...friction plate of brake disc, 140...brake piston, 1 42...Brake spring, 144a, 144b...Retaining member, 146...Accommodating portion of brake piston, 147a, 147b...Inner diameter portion of retaining member, 150...Facing surface of brake casing, 152...Brake chamber, 154...Brake release pressure oil passage, 156...Communication hole, 158...Slit, 160...End surface of brake piston on the electric motor side, 162...Edge of end surface of brake piston, 164...Output shaft, 166...Reduction gear casing, 168...Internal space of reduction gear casing, 170...First stage planetary gear mechanism, 172...Second stage planetary gear mechanism, 174...Internal space of brake mechanism, 176...Internal space of electric motor

Claims

1. An electric motor, a reducer that reduces the rotation speed of the electric motor; a brake mechanism disposed between the electric motor and the reducer to stop rotation of the reducer; The brake mechanism includes: A brake casing; a brake disc fixed to the shaft of the electric motor; a brake piston in frictional contact with the brake disc; a brake spring that biases the brake piston toward the brake disc; a brake chamber defined by the brake casing and the brake piston; a brake release port provided in the brake casing, the brake release port supplying hydraulic oil from an external hydraulic source to the brake chamber, the hydraulic oil moving the brake piston toward the electric motor against the biasing force of the brake spring and separating the brake piston from the brake disc; a communication hole formed in the brake piston and communicating from the brake chamber side to the electric motor side; a discharge port provided in a housing of the electric motor, for discharging hydraulic oil that has passed through the electric motor from the brake chamber through the communication hole of the brake piston; a supply path formed between the brake piston and the brake disc when the brake piston moves toward the electric motor, for supplying hydraulic oil supplied to the brake chamber to the reducer.

2. A slit is formed in the end surface of the brake piston on the electric motor side, 2. The rotary drive system according to claim 1, wherein the slit extends from the communication hole to an edge of the end face on the electric motor side.

3. The electric motor is a stator fixed to the housing; a rotor that rotates with the shaft when a current is applied to it; 3. The rotary drive system according to claim 1, wherein the hydraulic oil passes through a gap between the rotor and the stator, passes through the electric motor, and is discharged from the discharge port.

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