JP7115401B2 - motor - Google Patents

Description

The present invention relates to motors.

Conventionally, a motor is used as a drive source for a variable valve timing device that adjusts the relative phase between a crankshaft and a camshaft that determine the opening/closing timing of intake valves or exhaust valves of an engine (see, for example, Patent Document 1).

JP 2017-192214 A

By the way, in the variable valve timing device as described above, when the engine is in an idling stop state, the camshaft rotates to a predetermined position due to the biasing force of the valve spring provided in the valve, thereby driving the motor connected to the camshaft. The rotational position of the rotor is shifted.

Therefore, the motor needs to have a large holding torque so that the rotor does not rotate. As an example, there is a risk that the rotation characteristics of the motor will be degraded due to the increase in holding torque.
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a motor that can increase the holding torque in the idling stop state while suppressing deterioration of the rotation characteristics of the motor.

The motor that solves the above problems is connected to a camshaft (4) that receives the biasing force of a spring (6) of a valve (5) of an engine (1), and has a motor body (11) that adjusts the opening/closing timing of the valve. and a control circuit (12) for controlling the motor body, the motor body having a three-phase winding (22) to which a three-phase alternating current is supplied, the control circuit being controlled by the engine when the engine is running. In a certain case, an alternating current operation is performed to supply a three-phase alternating current to the three-phase winding, and when an idling stop signal indicating that the engine is in an idling stop state is input, the alternating current operation is performed. A motor that implements DC current operation for terminating and supplying DC current to a particular winding of said three-phase winding, wherein said control circuit controls, during said DC current operation, said one of said three-phase windings to Two-phase windings are energized, and among the three-phase windings, the combination of the two-phase windings is switched sequentially or at random .

According to the above aspect, in the idling stop state, by supplying a DC current to a specific winding of the three-phase winding, the winding is excited and the rotational position of the rotor of the motor main body is maintained. can obtain a holding torque for Therefore, restrictions such as the shape of the rotor in the motor main body can be reduced, so that the holding torque in the idling stop state can be increased while suppressing deterioration in rotation characteristics.

1 is a schematic diagram showing a variable valve timing device using a motor according to an embodiment; FIG. Sectional drawing which cut in the radial direction of the motor main body of the same embodiment. Explanatory drawing for demonstrating the electrical structure of the motor of the same embodiment. 4 is a timing chart for showing a control example (operation example) of the motor of the same embodiment;

An embodiment of the motor will be described below with reference to the drawings. In the drawings, for convenience of explanation, part of the configuration may be exaggerated or simplified. Also, the dimensional ratio of each part may differ from the actual one. Further, in the following description, unless otherwise specified, the terms "axial direction", "radial direction", and "circumferential direction" simply refer to the axial direction, radial direction, and circumferential direction of the motor (rotating shaft of the motor). shall mean the direction respectively.

As shown in FIG. 1, the motor 10 of the present embodiment is a brushless motor used as a drive source for a variable valve timing device 2 provided in an engine 1 of a vehicle. A rotary shaft 31 of the motor 10 is connected to the camshaft 4 via the phase adjustment mechanism 3, and the rotational driving force of the motor 10 (rotary shaft 31) controls the opening/closing timing of the valve 5 (the relative position of the camshaft 4 with respect to the crankshaft). phase) can be adjusted. The valve 5 is constantly biased in the valve closing direction by a valve spring 6 .

As shown in FIGS. 1 and 2, the motor 10 includes a motor body 11 and a control circuit 12 integrated with the motor body 11 . Motor body 11 includes stator 20 and rotor 30 .

As shown in FIG. 2, the stator 20 has a substantially annular stator core 21 having twelve teeth 21a and windings 22 wound around the teeth 21a. A slot is formed between each tooth 21a. Three-phase alternating current is supplied from the control circuit 12 to the windings 22 wound around the teeth 21a. The winding 22 has a U-phase winding 22u supplied with a U-phase current, a V-phase winding 22v supplied with a V-phase current, and a W-phase winding 22w supplied with a W-phase current.

As shown in FIG. 2 , the rotor 30 has a rotating shaft 31 and a cylindrical rotor core 32 fixed to the rotating shaft 31 . The rotating shaft 31 of the rotor 30 is supported by bearings (not shown) so that it can rotate inside the stator 20 in the radial direction while being surrounded by the teeth 21a. A plurality of magnetic pole portions 33 are formed on the outer peripheral edge of the rotor 30 so as to face the teeth 21a surrounding the rotor 30 .

More specifically, each magnetic pole portion 33 is formed by embedding flat plate-like permanent magnets 34 a and 34 b in the outer peripheral portion of the rotor core 32 . That is, the motor main body 11 of the present embodiment is configured as a motor having a permanent magnet-embedded (IPM side) rotor. Specifically, the outer peripheral edge of the rotor core 32 is provided with magnet receiving holes 35a and 35b formed along the axial direction at equal intervals (at intervals of 45°) in the circumferential direction. Each magnetic pole portion 33 is formed by accommodating and fixing each permanent magnet 34a, 34b in each magnet accommodating hole 35a, 35b in a manner perpendicular to the radial direction of the rotor core 32. As shown in FIG.

In the present embodiment, the permanent magnets 34a and 34b are arranged in the magnet housing holes 35a and 35b such that the radially outer surface is the N pole, and the radially outer surface is the first permanent magnet 34a. and a second permanent magnet 34b arranged to be the south pole. The first permanent magnets 34a and the second permanent magnets 34b are housed in the magnet housing holes 35a and 35b alternately in the circumferential direction. That is, the magnetic pole portions 33 having the same polarity composed of the first permanent magnets 34a and the magnetic pole portions 33 having the same polarity composed of the second permanent magnets 34b are alternately formed along the circumferential direction. As a result, a total of eight magnetic pole portions 33 are formed at intervals of 45° in the circumferential direction. That is, the motor main body 11 of this embodiment is an 8-pole 12-slot brushless motor.

As shown in FIG. 3, the control circuit 12 controls the driving of the motor main body 11 by setting the timing of energization of the windings 22 and generating a three-phase alternating current. A DC power source E1 is connected to the control circuit 12 . Specifically, the power terminal T1 of the control circuit 12 is connected to the positive pole of the DC power supply E1, and the power terminal T2 of the control circuit 12 is connected to the negative pole of the DC power supply E1.

As shown in FIG. 3 , the control circuit 12 includes an inverter circuit 40 and a control section 50 . Inverter circuit 40 is connected to windings 22 u, 22 v, and 22 w of winding 22 .
The inverter circuit 40 is, for example, a three-phase inverter circuit for generating three-phase drive power with a phase difference of 120° from the DC power supplied from the DC power supply E1. The inverter circuit 40 has six bridge-connected switching elements 41 to 46 . The switching elements 41 to 46 are, for example, N-channel MOSFETs (Metal-Oxide Semiconductor Field-Effect Transistors). Diodes D1 to D6 are reversely connected to the switching elements 41 to 46, respectively, for flowing return currents. In inverter circuit 40, U-phase switching element 41 and switching element 42 are connected in series between high-potential power line VB1 and low-potential power line VB2, and V-phase switching element 43 and switching element 44 are connected in series. are connected in series, and the W-phase switching element 45 and switching element 46 are connected in series. The connection points of the switching elements 41, 43, 45 on the high potential side and the switching elements 42, 44, 46 on the low potential side are connected to one ends of the windings 22u, 22v, 22w, respectively. Further, the other ends of the windings 22u, 22v, 22w of this embodiment are connected at the neutral point P. That is, the windings 22 of the present embodiment are connected in a so-called star connection. Note that the windings 22 are not limited to the star connection, and may be the delta connection.

The control unit 50 is connected to the gates of the switching elements 41-46 and controls ON/OFF of the switching elements 41-46. As a result, the DC current from the DC power supply E1 is converted into a three-phase AC current and supplied to the brushless motor 10 .

The control unit 50 of the present embodiment controls ON/OFF of the switching elements 41 to 46 based on an input signal SI input from the engine ECU 7, for example. Here, when the input signal SI is high level, it indicates that the engine 1 is in the normal driving state, and when it is low level, it indicates that the engine 1 is in the idling stop state. More specifically, the idling stop signal is input to the control unit 50 when the input signal SI changes from high level to low level. Also, when the input signal SI changes from low level to high level, the engine start signal is input to the control unit 50 .

The control unit 50 performs alternating current operation to supply three-phase alternating current to the windings 22u, 22v, and 22w when the input signal SI indicating that the engine 1 is in the normal driving state is at a high level. Further, when the input signal SI indicating that the engine 1 is in the idling stop state is at a low level, the control unit 50 supplies a DC current to the two-phase windings 22u, 22v among the windings 22u, 22v, 22w. Powered direct current operation is implemented. When comparing the average voltage value during DC current operation with the average voltage value during AC current operation, the control unit 50 lowers the average voltage value during DC current operation.

Next, an operation example (action) of the motor 10 of this embodiment will be described mainly with reference to FIG.
For example, when a high-level input signal SI is input from the engine ECU 7, the control unit 50 of the motor 10 assumes that it is in a normal drive state, and performs alternating current operation to supply three-phase alternating current to the windings 22u, 22v, and 22w. do.

As shown in FIG. 4, at time t1, for example, when the vehicle brake is operated and the vehicle speed becomes 0, the engine 1 shifts to the idling stop state. At this time, a low-level input signal SI is input to the control unit 50 from the engine ECU 7 .

When a low-level input signal SI is input from the engine ECU 7, the control unit 50 determines that the engine is in the idling stop state and stops the AC current operation, and performs the DC current operation. Specifically, the control unit 50 controls the switching elements 41 to 46 to supply DC current to the two-phase windings 22u and 22v among the three-phase windings 22u, 22v and 22w. As a result, the two-phase windings 22 u and 22 v are excited to generate holding torque between the windings 22 u and 22 v and the rotor 30 . By setting this holding torque to a torque that resists the biasing force of the spring 6 provided in the valve 5, unintended rotation of the rotor 30 and the camshaft 4 can be suppressed.

As shown in FIG. 4, at time t2 after time t1, for example, when the operation of the vehicle brake is released, the engine 1 shifts to the normal driving state. At this time, a high-level input signal SI is input to the control unit 50 from the engine ECU 7 .

When a high-level input signal SI is input from the engine ECU 7, the control unit 50 assumes that the normal drive state is in effect, and terminates the DC current operation, and at the same time, performs the AC current operation. That is, the alternating current operation is performed immediately after the direct current operation, and the non-energization time (zero potential time) is substantially zero. As a result, the valve timing can be adjusted immediately after the engine 1 is started.

The effect of this embodiment will be described.
(1) By supplying DC current to specific windings 22u, 22v of the windings 22u, 22v, 22w in the idling stop state, the windings 22u, 22v are excited and the motor main body 11 A holding torque for holding the rotational position of the rotor 30 can be obtained. Therefore, restrictions such as the shape of the rotor 30 in the motor main body 11 can be reduced, so that it is possible to increase the holding torque in the idling stop state while suppressing deterioration in rotation characteristics. By suppressing the deterioration of the rotation characteristics of the motor body 11, it is possible to contribute to the improvement of the responsiveness of the engine 1. Further, in order to hold the positions of the rotor 30 and the camshaft 4, a sensor for position detection and a feedback circuit for fine adjustment of the position are required. It can be realized with a simple and simple configuration in which direct current is supplied to the windings.

(2) When an engine start signal indicating that the engine 1 has been started is input after the idling stop state has ended, the DC current operation is terminated. can be done.

(3) By performing AC current operation at the same time as the completion of DC current operation, it is possible to quickly adjust the valve timing from the start of the engine 1 .
(4) When comparing the average voltage value during DC current operation and the average voltage value during AC current operation, the control unit 50 lowers the average voltage value during DC current operation, thereby saving power. can do.

It should be noted that each of the above-described embodiments can be implemented with the following modifications. Each of the above-described embodiments and the following modifications can be implemented in combination with each other within a technically consistent range.

In the above embodiment, the DC current is supplied only to the windings 22u and 22v during the idling stop state from time t1 to t2, but the present invention is not limited to this. For example, the combination of the windings 22u, 22v, and 22w may be changed between times t1 and t2 in the idling stop state. When supplying DC current to two-phase windings, a combination of the windings 22u and 22v, a combination of the windings 22u and 22w, and a combination of the windings 22v and 22w can be considered. At least two of them may be switched at times t1 to t2 in the idling stop state. Moreover, when using the above three combinations, they may be switched sequentially or randomly.

Further, when a DC current is supplied to the winding 22u and the winding 22v during the idling stop state from time t1 to t2, in the subsequent idling stop state, another combination of windings (the winding 22u and the winding A combination of wires 22w or a combination of windings 22v and 22w) may also be used. Also in this case, the above three combinations may be switched sequentially or randomly.

As described above, as a method for determining the two-phase windings to which the DC current is supplied during the DC current operation, the windings 22u, 22v, 22w deterioration bias can be suppressed.

In the above-described embodiment, direct current is supplied to the two-phase windings 22u and 22v during the idling stop state from time t1 to t2, but the present invention is not limited to this.
For example, a DC current may be supplied to the three-phase windings 22u, 22v, and 22w between times t1 and t2 in the idling stop state. In this case, since the DC current is fed to all of the windings 22u, 22v, and 22w, the windings can Power can be supplied to the lines 22u, 22v, and 22w in a well-balanced manner, and deterioration of only specific windings can be suppressed.

Also, during the idling stop state between times t1 and t2, a direct current may be supplied to one of the three-phase windings 22u, 22v, and 22w.
- In the above-described embodiment, the motor main body 11 and the control circuit 12 are integrated, but a separate structure may be employed.

- In the above embodiment, the so-called IPM type rotor 30 in which the permanent magnets 34a and 34b are arranged in the rotor core 32 is adopted, but the present invention is not limited to this. For example, a Lundell type in which a disk-shaped field magnet having a magnetization direction along the axial direction is sandwiched between a pair of core members having claw-shaped magnetic poles extending in the axial direction, and a field magnet on the outer peripheral surface of the core member. A surface magnet type (SPM type) equipped with a magnet may be employed.

In the above embodiment, the motor main body 11 is an 8-pole 12-slot brushless motor, but the number of poles and the number of slots may be appropriately changed according to the specifications and the like.
・In the above embodiment, the idling stop state is shifted to the normal drive state when the brake operation is released. may shift from the idling stop state to the normal drive state. Even in such a case, it is preferable to perform alternating current operation at the same time as the end of direct current operation, as in the above embodiment.

・In the above embodiment and modification, the AC current operation is performed at the same time as the DC current operation is completed. good too.

- In the above-described embodiment, the motor 10 is used as a drive source for the variable valve timing device 2, but the present invention is not limited to this. It can be widely used in systems that require holding torque on demand. As a result, the motor can be designed in accordance with the system, and the degree of design freedom can be increased.

DESCRIPTION OF SYMBOLS 1... Engine, 4... Camshaft, 5... Valve, 6... Spring, 10... Motor, 11... Motor body, 12... Control circuit, 22... Winding (three-phase winding), 22u... U-phase winding, 22v . . . V-phase winding, 22w .. W-phase winding, SI .

Claims (4)

A motor body (11) that is connected to a camshaft (4) that receives the biasing force of a spring (6) of a valve (5) of an engine (1) and that adjusts the opening/closing timing of the valve, and a control that controls the motor body. a circuit (12);
The motor body comprises a three-phase winding (22) fed with a three-phase alternating current,
The control circuit performs an alternating current operation to supply a three-phase alternating current to the three-phase winding when the engine is in a driving state, and an idling stop signal indicating that the engine is in an idling stop state. is input, the motor terminates the AC current operation and supplies a DC current to a specific winding of the three-phase windings, wherein
The control circuit energizes two-phase windings of the three-phase windings when the direct current is operated,
A motor, wherein the combination of the two-phase windings among the three-phase windings is sequentially or randomly switched for each DC current operation period . 2. The motor according to claim 1 , wherein said control circuit terminates said direct current operation when an engine start signal indicating that said engine has been driven is input after said idling stop state has ended. 3. The motor of claim 2 , wherein said control circuit implements said alternating current operation upon termination of said direct current operation. Claims 1 to 3 , wherein the control circuit lowers the average voltage value during direct current operation when the average voltage value during direct current operation and the average voltage value during alternating current operation are compared. 1. The motor according to any one of .

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