WO2002014675A1

WO2002014675A1 - Controller for exhaust gas recirculation valve

Info

Publication number: WO2002014675A1
Application number: PCT/JP2000/005467
Authority: WO
Inventors: Satoshi Kawamura; Sotsuo Miyoshi; Toshihiko Miyake; Youichi Fujita
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2000-08-15
Filing date: 2000-08-15
Publication date: 2002-02-21

Abstract

A controller for an exhaust gas recirculation valve in an exhaust gas recirculation system comprises means for detecting step-out by comparing the terminal voltage of each phase coil of a stepper motor serving as a drive source with a reference value. Step-out can be detected reliably without requiring any extra unit or member.

Description

Description Exhaust gas recirculation pulp control equipment Technical field

The present invention relates to an exhaust gas recirculation system provided in an exhaust gas recirculation system.

EGR (ExhaustGasRecircuulatoion) ". This relates to a valve control device. Background art

FIG. 1 is a configuration diagram in which a valve element (open / close valve) 11 of an EGR valve is disposed in an exhaust gas recirculation circuit c that communicates an exhaust passage a and an intake passage b of the engine E. The control device of the EGR valve controls the driving of a stepping motor 1 (hereinafter, referred to as motor 1) as a drive source by an engine controller unit (hereinafter, ECU) 31, for example. The valve 11 is controlled to open and close by the motor 1. By controlling the motor 1, the valve 11 is adjusted and held at the target engagement position.

A conventional control device for this type of E-valve applies a predetermined return torque in the valve closing direction of the valve body 11 by biasing means and drives the valve body 11 by driving the motor 1 in the valve opening direction. A motor torque that varies in the valve direction is applied, and the opening and closing of the valve body 11 is controlled by the torque balance.

FIG. 2 is a longitudinal sectional view in which a configuration of a control device of the EGR valve is partially cut away. In the figure, reference numeral 1 denotes a stepping motor as a driving source, for example, a configuration in which a cylindrical rotor 4 is arranged on the inner diameter side of a step 3 in which four-phase excitation coils 2 are mounted in 48 slots. It is. A cylindrical magnet 5 in which the N pole and the S pole are alternately magnetized 24 poles is fitted around the outer periphery of the mouth 4. Have been. Further, a threaded motor shaft 7 is provided on the inner diameter side of the female screw member 4 through the female screw member 6, and the rotational movement of the mouth 4 is moved up and down by the motor shaft 7 through the female screw member 6. The lower end of the motor shaft 7 is connected to a valve shaft 10 via two connecting plates 8 and 9, and the lower end of the valve shaft 10 is The valve body 11 is fixed to the section, and the valve opening is adjusted by controlling the distance by which the valve body 11 is moved up and down on the valve seat 12. The upper connecting plate 8 is fixed to the lower end of the motor shaft 7, and the lower connecting plate 9 is fixed to the upper end of the valve shaft 10.

Then, the L-shaped engaging claw 13 formed downward on the upper connecting plate 8 is engaged with the lower connecting plate 9, and the valve body 11 is brought into close contact with the valve seat 12 even in the fully closed state. The motor shaft 7 and the upper connecting plate 8 can move in the valve closing direction. The lower connecting plate 9 is urged downward (in the valve closing direction) by the outer compression coil spring 14 and the inner compression coil spring 15, and when the valve body 11 is moved up and down (opened and closed), both compression coils are moved. The lower connecting plate 9 is held by the springs 14 and 15 in a state where the lower connecting plate 9 is engaged with the engaging claws 13 of the upper connecting plate 8, and the valve shaft 10 is vertically moved integrally with the motor shaft 7. It works. The opening of the valve seat 12 communicates with an inlet port 17 through which exhaust gas flows in from the exhaust passage a side and an output port 18 through which exhaust gas flows out to the surge tank side.

Next, the operation of the E-valve will be described. When the energization to the excitation coil 2 of each phase of the stepping motor 1 is sequentially switched by the two-phase excitation method, the mouth 4 rotates, and the rotating motion is changed to the linear motion by the female screw member 6, and the motor shuffling is performed. Transmitted to 7 At this time, when the rotation direction of the stepping motor 1 is the forward rotation direction, the motor shaft 7 is —Because the valve shaft 10 is piled up by the spring force of the outer compression coil spring 14 via ports 8 and 9 and moved upward, the valve body 11 is moved through the valve shaft 10 to the valve seat 1 2 Move in the direction away from (valve opening direction). This allows the inlet port 17 and the outlet port 18 to communicate with each other. By adjusting the distance between the valve body 11 and the valve seat 12 (valve opening), the amount of exhaust gas recirculation can be adjusted. Is done.

On the other hand, when the rotation direction of the stepping motor 1 is the reverse direction, the motor shaft 7 moves downward (valve closing direction), and the valve shaft 10 moves downward integrally with this. As a result, the valve element 11 moves in the direction approaching the valve seat 12, and finally, the valve element 11 is fitted and closely attached to the valve seat 12, and becomes a fully closed state. After that, when the stepping motor 1 rotates in the reverse direction, the motor shaft 7 moves further downward by staking the spring force of the inner compression coil spring 15 and the valve shaft 10 and the valve body 11 Is overstroked downward in the stroke of the inner compression coil spring 15. As a result, the valve element 11 is more strongly pressed against the valve seat 12, and the recirculation of the exhaust gas is reliably shut off.

A hole IC 20 as a rotation sensor is disposed above the mouth 4 in the housing 19. This Hall IC 2 ◦ is one in which the Hall element and the IC for amplification are integrated. On the other hand, at the upper end of the mouth 4, a rotation detecting magnetizing portion 21 is formed as a rotation detecting portion, in which N and S poles are alternately magnetized at a fixed pitch. The rotation of the section 21 is detected by the Hall IC 20. Then, the occurrence of step-out is detected based on the output signal of the hall IC 20.

Since the conventional exhaust gas recirculation valve control device is configured as described above, a Hall IC 20 as a rotation sensor is arranged at a limited location above the roof 4 in the motor housing 19. However, there is a problem that the configuration of the entire apparatus becomes complicated and large, and the apparatus becomes expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. An object of the present invention is to provide a control device for an exhaust gas recirculation valve which can detect the occurrence of step-out without using Ic. Disclosure of the invention

A control device for an exhaust gas recirculation valve according to the present invention includes a valve shaft having an on-off valve, a return spring for urging the valve shaft in a closing direction, and a motor shaft acting on the valve shaft. And a control means for controlling the driving of the stepping motor, and a step voltage is detected by comparing the terminal voltage of each phase coil of the stepping motor with a predetermined reference value. A step-out detecting means.

This makes it possible to reliably detect the occurrence of step-out without using a special device member. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic explanatory view of an engine exhaust system.

Fig. 2 is a longitudinal sectional view of the EGR valve driven by a steering motor.

FIG. 3 is a drive control circuit diagram of the stepping motor according to the present invention.

FIG. 4 is an equivalent circuit diagram of the steering mode.

FIG. 5 is a terminal voltage waveform diagram of each phase coil during a stepping mode when no step-out occurs.

Fig. 6 is an operation waveform diagram of the mouth of the stepping mode when step-out does not occur.

FIG. 7 is a terminal voltage waveform diagram of each phase coil in the stepping mode when step-out occurs. FIG. 8 is an operation waveform diagram of the mouth of the stepping mode when step-out occurs. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, in order to explain this invention in greater detail, the preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Embodiment 1

FIG. 3 is a block diagram of a drive control circuit (hereinafter referred to as ECU) 31 for outputting a drive pulse signal to the excitation coils 2a to 2d of each phase of the steering mode 1. The drive control circuit 31 includes a central processing unit 32 as a control means, which is a CPU, storage circuits ROM and RAM, and a water temperature sensor that detects an engine cooling water temperature and outputs a signal corresponding to the detected temperature. A voltage level correction circuit 33 that amplifies the signal and a signal from the intake air amount sensor of the engine to correct the required voltage, and A / D converts the signal output from the voltage level correction circuit 33 D Comparator 34, a waveform shaping circuit 35 that shapes the pulse voltage output from the ignition coil according to the engine speed, and a stepping spider 1 from the central processing unit 32. It is provided with a drive circuit 36 that converts a control signal to be controlled into a drive pulse signal and supplies the drive pulse signal to the excitation coils 2 a to 2 d of each phase of the stepping motor 1.

A control program for controlling the steering mode 1 is stored in the storage circuit ROM, and the central processing unit 32 drives the steering mode 1 in accordance with the control program stored in the storage circuit ROM, and By controlling the opening and closing of 11, the flow rate of the air passing through the bypass passage is controlled.

Fig. 4 is the equivalent circuit diagram of stepping mode 1, and the excitation coils of each phase are The circuits 2a to 2d are connected to the output terminals of the ECU 31 via switching circuits 37a to 37d. Each of the switching circuits 37a to 37d is composed of a switching transistor 38 and a diode 39. 40 is an OR circuit that detects the terminal voltage of the excitation coils 2a to 2d of each phase, and 41 is a circuit that compares the output of the OR circuit 40 with a reference value T determined in advance by experiment or combi simulation. And a comparison circuit as step-out detecting means for detecting the occurrence of step-out.

Next, the operation will be described.

The central processing unit 32 receives the signal output from the voltage level correction circuit 33 via the AZD converter 34, and receives the pulse voltage output from the ignition coil via the waveform shaping circuit 35. A drive pulse signal is generated for the stepping motor 1 according to the control program stored in the storage circuit ROM, and supplied to the stepping motor 1 via the driving circuit 36.

The above drive pulse signal is supplied to the switching circuits 37a to 37d by applying 37a, 37c, 37a, 37d, 37d, 37c, 37c, 37b. Since they are supplied simultaneously as a pair, the excitation coils 2a to 2d of each phase of the stepping motor 1 have 2a, 2c, 2a, 2d, 2d, 2c, 2c, 2c. Excitation current flows from the 12 V power supply simultaneously with that of b.

In this case, if the stepping motor 1 is driven normally, the terminal voltages generated in the exciting coils 2a to 2d of each phase of the stepping motor 1 change regularly as shown in Fig. 5, The rotation angle of the mouth 4 of the stepping motor 1 also rises regularly as shown in Fig. 6.

However, when step-out occurs due to vibration, increased load, etc., the terminal voltage waveform of the coil in the step-out phase greatly changes as shown in FIG. 7, and as shown in FIG. , The rotation angle of Rho 4 also fluctuates greatly, and the original state It will take a long time to return to. Then, the terminal voltages generated in the excitation coils 2a to 2d of each phase are taken out through the OR circuit 40, and are compared with the reference value T predetermined by the comparing means 41, and the value exceeding the reference value T is obtained. When there is a fluctuation, a signal indicating that step-out has occurred is transmitted to the CPU 32 of the drive control circuit 31. When the CPU 32 receives the signal indicating that the step-out has occurred, the CPU 32 notifies the occurrence of the step-out by a notifying means (not shown) such as a lamp or a speaker. As described above, according to the first embodiment, it is possible to reliably detect the occurrence of step-out without using any special device member. Industrial applicability

As described above, the exhaust gas recirculation valve control device according to the present invention quickly returns a part of the exhaust gas from the exhaust passage a to the intake passage b in response to a change in the operating state of the engine. Especially suitable for.

Claims

The scope of the claims

1. A valve shaft having an on-off valve, a return spring that urges the valve shaft in the closing direction, a steering motor that drives a motor shaft that acts on the valve shaft, and a stepping motor that drives the motor shaft. Control means for controlling the operation of the exhaust gas recirculation valve, and step-out detecting means for detecting step-out by comparing a terminal voltage of each phase coil of the stepping motor with a reference value and detecting step-out. apparatus.