JP4952666B2 - Electric power steering device - Google Patents

Description

The present invention relates to an electric power steering apparatus including an electric motor that outputs an auxiliary torque to a steering wheel of a vehicle and a control device that controls driving of the electric motor. In particular, the electric motor, a gear, and a control device are integrated. It is related to conversion.

Conventionally, an electric motor that outputs an auxiliary torque to a steering wheel of a vehicle, and a control device that drives and controls the electric motor, the control device includes a plurality of semiconductor switching elements for switching the current of the electric motor, and 2. Description of the Related Art There is known an electric power steering device that includes a microcomputer that generates a drive signal for driving the semiconductor switching element and is attached to an electric motor. A high-frequency leakage current generated by switching control of the electric motor drive flows in the path of the control device, the electric motor harness, the electric motor, and the electric motor winding. This leakage current may generate radiated or conductive electromagnetic interference, which may cause noise interference, for example, in radio and audio equipment.

Japanese Patent Laid-Open No. 2002-120739

The control device for the electric power steering device described above integrates the electric motor and the control device, the electric motor wiring is connected at a short distance, and the semiconductor switching element is disposed in the vicinity of the electric motor wiring to suppress radiation noise. It has a structure to do. However, if the electric power steering device is installed in the vehicle interior, noise interference may occur depending on the wiring and position of radio / audio.

An object of the present invention is to solve the above-mentioned problems, and in an electric motor type power steering device in which an electric motor and a control device are integrated, noise generation is further reduced and noise disturbance is suppressed. Objective.

The present invention relates to an electric power steering device integrated with an electric motor that outputs auxiliary torque to a steering wheel of a vehicle and a control device that controls driving of the electric motor. The electric motor includes a conductive motor case; In order to fix the motor case and the control device, a part of the motor case is provided with a mounting portion. The control device includes a power board portion on which a plurality of semiconductor switching elements for controlling the current of the electric motor are mounted, a handle A control board portion mounted with a microcomputer for generating a drive signal for driving the semiconductor switching element based on the steering torque of the vehicle, a connector electrically connected to the vehicle side, and a housing to be attached to the motor case The ground wiring of the semiconductor switching element of the power board part is mainly composed of the connector Is connected with the position, arranged connection members to be connected with the motor case, the power board abuts on a part of the housing while being built in the housing, the connecting member, the intermediate member and the fixing member One of the intermediate members is in contact with a part of the ground wiring, the other of the intermediate member is in contact with the housing, and the mounting portion, the housing, and the intermediate member are collectively connected and fixed by the fixing member, whereby the power board and the housing Are mechanically fixed simultaneously, and the ground wiring of the power board, the intermediate member, and the mounting portion are electrically connected .

The connecting member of the present invention comprises a substantially cylindrical portion mounted on the inner side of the motor case and a connecting terminal portion extending from a part thereof, and the connecting terminal portion is provided in a housing containing the control device. It penetrates the hole and is electrically connected to a part of the ground wiring of the power board portion .

According to the electric power steering device of the present invention, the electric motor driving ground of the control device and the motor case are directly and electrically connected with a simple structure, so that the radioactive and conductive electromagnetic interference generated by the device can be reduced. Suppresses and suppresses noise interference such as in-vehicle radio / audio.

Embodiment 1 FIG.
Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts and members.
1 is a circuit configuration diagram showing an electric power steering apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view showing the whole apparatus.
First, an electrical description will be given with reference to FIG. In this electric power steering apparatus, the electric motor 11 includes a magnet-type rotor (FIGS. 2 and 30), a three-phase motor winding 14 wound around a stator (FIGS. 2 and 31), and the like. . In the control device 1, the steering torque detected by the torque sensor 4 attached to the steering wheel and information from the vehicle information unit 3 that outputs vehicle information such as the vehicle speed are input to the control device 1. Further, the rotation output shaft (FIGS. 2 and 32) of the electric motor 11 reduces the steering force of the handle via the gear portion (FIGS. 2 and 33). The control device 1 mainly inputs the above information, calculates an assist target torque for steering the steering by the microcomputer 7, outputs a drive signal for driving the semiconductor switching elements Q1 to Q6, and the semiconductor according to this drive signal. From the control board part 6 which consists of the drive circuit 8 which drives the switching elements Q1 to Q6, and the semiconductor board switching elements Q1 to Q6 that send drive current to the motor winding 14 of the electric motor 11, for example, the power board part 5 on which the FET is mounted It is configured.

In the electric motor 11, a stray capacitance 15 is electrically present between the motor case 17 and the motor winding 14. A high-frequency current is generated by switching control of the FETs Q <b> 1 to Q <b> 6 of the power substrate unit 5, and this high-frequency current passes through the motor wiring 16, the motor winding 14, the stray capacitance 15, and the electrical connection means 10. Return to The ground 9 passes through the ground pin 13 of the connector (FIGS. 2 and 18) via the ground wiring in the control device 1, and finally returns to the negative terminal 19 of the battery 2.

Since the electrical connection means 10 does not exist in the conventional apparatus, the vehicle body 20 is grounded 38 from the motor case 17 or via the mechanism part of the gear part (FIGS. 2 and 33) and exists between the vehicle body 20. A high-frequency current flows through the stray capacitance. The electric path to the ground of the power board portion is long and a large loop is formed. Further, the ground potential of the vehicle body 20 fluctuates to generate electromagnetic interference. However, the provision of the electrical connection means 10 cuts off the flow path to the vehicle body 20 and returns to the power board portion ground 9 with the shortest distance without adverse effects, thereby suppressing radioactive and conductive electromagnetic interference. be able to.

Next, a structural description will be given based on FIG. The motor 11, the control device 1, and the gear unit 33 are arranged along the motor output shaft 32. The control device 1 is mounted inside the housing 21 and the cover 22 on the motor case 17 side and the gear part 33 side, respectively, and has a two-layer structure in which the control board part 6 and the power board part 5 are separated. Although not shown, there are electrical wirings connecting the two substrates. A part of the motor case 17 is provided with a mounting portion 34 for mounting on the control device 1 or the gear portion 33. The motor case 17 is made of a conductive member, for example, iron. A screw 35 is inserted into the mounting portion 34, and the screw 35 is screwed into a relay member 36 with the power board portion 5. The relay member 36 is also made of a conductive member such as copper.

On the other hand, FETs (FIG. 1, Q1 to Q6) are mounted on the power substrate unit 5, and are metal substrates for heat dissipation of these FETs. The ground wirings of the FETs Q4 to Q6 are finally extended to the vicinity of the hole where the relay member 36 is inserted, and a copper nut 37 is used to electrically and mechanically fix the ground wiring and the relay member 36. Although not shown, this ground wiring is connected to a ground pin (FIGS. 1 and 13) of the connector 18. A connection portion with the ground pin of the connector 18 is referred to as a first connection portion, and a ground wiring in contact with the relay member 36 of the power board portion is referred to as a second connection portion. The nut 37, the relay member 36, and the screw 35 constitute a connecting member, the screw 35 corresponds to a fixing member, and the relay member 37 and the nut 37 correspond to an intermediate member.
Thus, the ground 9 is electrically connected to the nut 37, the relay member 36, the screw 35, and the motor case 17.

Further, in order to fix the power board portion 5 itself and for heat dissipation, it abuts on the housing 21, which is made of, for example, aluminum and abuts on the motor case 17. As a result, the power board 5 is mechanically fixed to the motor case 17. Therefore, the heat generated by the FET is conducted to the power substrate portion 5, the housing 21, and the motor case 17, so that the heat dissipation can be improved. Further, since the cover 22 on the control board 6 side is attached to the gear 33, it is made of, for example, aluminum. In this case, the cover 22 can also contribute to heat dissipation.

As described above, the ground can be mechanically and electrically connected easily through the intermediate member up to the power board portion on which the FET is mounted using the mounting portion of the motor case. The power board portion 5 is disposed closer to the motor 11, and the ground connection path is also linear and can be further shortened.
The control board 6 and the power board 5 are a single board, and even if they are partially separated from the power part and the control part, it is easy to adopt the same structure.
Further, although the screw 35 is used for the mounting portion of the motor case, it is not limited to the screw, but may be a conductive member and a fixing member that fixes the motor case 11 and the relay member 36.

Further, although the nut 37 and the relay member 36 have been described as separate bodies, they may be integrated. In this case, the ground is secured by contact between the bottom surface of the nut (37) and the power board part 5, and the relay member part (36) is brought into contact with the inside of the motor case 17 without sandwiching the power board part 5. Will be connected. In this case, the fixing member 35 is a member for fixing the motor case 17 and the relay member (36), and may not be conductive.
Furthermore, the ground wiring is not wired with the same thickness from the first connecting portion to the second connecting portion, but is thickly wired because the control current flows from the sources of the FETs Q4 to Q6 to the first connecting portion. The wiring up to the second connection portion can be made thin, and the area of the substrate can be used effectively.

Embodiment 2. FIG.
Next, a second embodiment will be described with reference to FIG. The electric circuit diagram in the structure of FIG. 3 is the same as FIG. As in FIG. 2, the motor 11 has a rotor and a stator (both not shown) built in the motor case 17. The control device 1 includes a power board portion 5 and a control board portion 6 and includes a housing 21 and a cover 22 for incorporating these board portions. The motor 11 has a motor output shaft 32 disposed in the center of the housing 21 and is fastened with screws 27. Further, the cover 22 fixed to the gear portion (FIGS. 2 and 33) incorporates the controller 1 and is fastened together with the housing 21. The control device 1 has an electrical wiring 23 for electrically connecting both board portions. A connector 18 for electrical connection with the vehicle side is connected and fixed to both boards.

In the motor 1, a connection member 24 for ground connection is mounted inside the motor case 17. The connection member 24 is made of a conductor, for example, a phosphor bronze plate, and includes a cylindrical portion 24a that is in close contact with the motor case 17 and an extended connection terminal portion 24b. The cylindrical portion 24a has a cylindrical shape with a part cut away to have elasticity so that it can be in close contact with the inner and inner peripheral surfaces of the motor case 17. The connection terminal portion 24b extends from the cylindrical portion 24a to the power board portion 5 in the motor output shaft direction.

The connection terminal portion 24 b passes through the hole 25 of the housing 21 and further passes through the hole 26 of the power board portion 5 and is inserted into a hole (not shown) on the component mounting surface of the power board portion 5. The insertion hole is connected to the ground pattern and forms a second connection portion. As a result, the ground of the control device and the connection member 24 are electrically connected, and further, the motor case 17 is also connected. The connection terminal portion 24b and the power board portion 5 may be connected by so-called snap fit, or may be connected by soldering. Further, the cylindrical portion 24 a may be welded to the motor case 17.

Embodiment 3 FIG.
Next, Embodiment 3 will be described with reference to FIG. The difference from FIG. 1 of the first embodiment is a capacitor 28. In the electrical connection means 10 in the control device, a coupling capacitor 28 is interposed between the ground 9 of the FETs Q4 to Q6 and the motor case 17. As a result, an AC component of the high-frequency current is allowed to flow, and a DC current is not allowed to flow. The capacitor 28 is disposed on the ground of the power board portion 5 in the vicinity of the location where the motor-side ground electrical connection means 10 is disposed, that is, in the vicinity of the second connection portion.

In addition, the ground wiring of the FETs Q4 to Q6 and the ground wiring to the second connection portion can be made thinner than the wiring to the first connection portion of the connector pin. This is because no direct current flows, but only an alternating current flows, so that a large current does not flow, and there is an effect that the substrate area can be used effectively. In addition, since a large current does not flow, there is no possibility that the ground wiring holding the coupling capacitor 28 is melted even if the wiring of the ground pin of the connector causes a contact failure.

As described above, according to this electric power steering device, by connecting the motor-side ground and the ground of the motor drive unit of the control device, the radiation and conductive electromagnetic interference generated by this device is suppressed, and the noise disturbance Can be suppressed. In addition, since the connecting member can be achieved with a simple configuration, the productivity of the apparatus can be improved.

1 is a circuit configuration diagram showing an electric power steering device according to Embodiment 1 of the present invention. FIG. It is a disassembled perspective view which shows the electric power steering apparatus of FIG. It is a disassembled perspective view which shows the electrically driven power steering apparatus which concerns on Embodiment 2 of this invention. It is a circuit block diagram which shows the electrically driven power steering apparatus which concerns on Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control apparatus, 5 Power board part, 6 Control board part, 7 Microcomputer, 8 Drive circuit, 9 Ground, 10 Electrical connection means, 11 Electric motor, 14 Motor winding, 15 Stray capacity, 17 Motor case, 24 Connection member, 34 mounting part, 36 relay member

Claims (2)

In an electric power steering device integrated with an electric motor that outputs an auxiliary torque to a steering wheel of a vehicle and a control device that controls driving of the electric motor,
The electric motor includes a conductive motor case, and a mounting portion in a part of the motor case for fixing the motor case and the control device,
The control device generates a drive signal for driving the semiconductor switching element based on a power board portion on which a plurality of semiconductor switching elements for controlling the current of the electric motor is mounted and steering torque of the steering wheel. It is mainly composed of a control board portion on which a microcomputer is mounted, a connector that is electrically connected to the vehicle side, and a housing that is attached to the motor case, and the ground wiring of the semiconductor switching element of the power board portion is In addition to being connected to a specific part of the connector, a connection member for connecting to the motor case is arranged, and the power board is built in the housing and a part thereof abuts the housing.
The connecting member includes an intermediate member and a fixing member, and one of the intermediate members is in contact with a part of the ground wiring, and the other of the intermediate member is in contact with the housing. The intermediate member is connected and fixed in a lump so that the power board and the housing are mechanically fixed at the same time, and the ground wiring of the power board, the intermediate member, and the mounting portion are electrically connected. An electric power steering device characterized by that. In an electric power steering device integrated with an electric motor that outputs an auxiliary torque to a steering wheel of a vehicle and a control device that controls driving of the electric motor,
The electric motor includes a conductive motor case and a housing that contacts the motor case and incorporates the control device ,
The control device generates a drive signal for driving the semiconductor switching element based on a power board portion on which a plurality of semiconductor switching elements for controlling the current of the electric motor is mounted and steering torque of the steering wheel. It is mainly composed of a control board portion on which a microcomputer is mounted and a connector electrically connected to the vehicle side, and the ground wiring of the semiconductor switching element of the power board portion is connected to a specific part of the connector. And arranging a connection member to be connected to the motor case,
The connection member includes a substantially cylindrical portion mounted on the inner side of the motor case, and a connection terminal portion extending from a part thereof. The connection terminal portion passes through a hole provided in the housing, and is connected to the ground. An electric power steering apparatus characterized by being electrically connected to a part of wiring.

Images