JP2002129988A - Intake air throttling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intake air throttling device capable of enhancing the resolution of a valve shaft rotation angle while always opening an intake air throttle valve provided with a drive motor and downsizing with a simple construction. SOLUTION: Since the first and second return springs 31 and 32 for energizing a valve shaft 12 in the valve opening and closing directions, respectively are used, there can be provided the intake air throttle valve which always opens at an intermediate openness position θN corresponding to a required intake air flow rate by changing the respective energizing forces of the springs 31 and 32. Further, since the spring constants K1 and K2 of the return springs 31 and 32 are different from each other, the gradient of a torque characteristic Tr generated by energizing the valve shaft is made to have two-stage characteristic. Thereby, since the variation Δθ1 of rotation angle to a drive torque Tr can be lessened by enlarging the spring constant K1 (a torque variation amount against the valve shaft rotation angle) in the two-stage characteristic, the resolution of rotation angle θ of the valve shaft 12 can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake throttle device, and more particularly to an intake throttle device for a diesel engine of an automobile or the like.

[0002]

2. Description of the Related Art An intake throttle valve for opening and closing an intake passage of a diesel engine, a drive motor for driving the intake throttle valve, and control means (hereinafter referred to as ECU) for controlling the drive motor.
) Is known.

[0003] Diesel engines are self-igniting by injecting fuel into compressed high-temperature air. Therefore, only when it is desired to stop the engine reliably (especially after stopping the fuel while stopping the engine while preventing engine vibration), It is desirable to shut off both fuel and air. For this reason, this intake throttle device is provided with the valve shaft of the intake throttle valve in the valve opening direction so that normal operation can be performed even when the drive motor for driving the intake throttle valve or the control system fails. A normally open intake throttle valve is provided by providing a return spring that biases the throttle valve.

[0004]

In the above-mentioned conventional configuration,
In order to balance the torque characteristics of the return spring with the torque characteristics of the drive motor without increasing the size of the drive motor, the spring constant of the return spring is set small. For this reason, the balance point between the two torque characteristics cannot be determined, and it may be difficult to perform feedback control by the ECU that controls the drive motor.

[0005] As a countermeasure, a reduction gear is provided between the valve shaft of the intake throttle valve and the drive motor to improve the resolution of the valve shaft rotation angle by the drive motor and improve feedback controllability. is there. However, when the reduction gear is mounted, there is a problem that the configuration becomes complicated and the size of the device becomes large.

[0006] In recent years, there has been an increasing demand for a high-density engine room from the viewpoint of improving the comfort of a vehicle, and it may be difficult to secure a space for mounting a reduction gear in an intake throttle device. Of course, there is a demand for downsizing of the intake throttle device itself.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object thereof is to improve the resolution of the valve shaft rotation angle while keeping the intake throttle valve driven by the drive motor normally open. Another object of the present invention is to provide an intake throttle device that can be downsized with a simple configuration.

[0008]

According to the first aspect of the present invention, an intake throttle valve for opening and closing an intake passage, a drive motor for driving a valve shaft of the intake throttle valve, and a control means for controlling the drive motor are provided. In the intake throttle device provided, first and second return springs having different spring constants are disposed at one end of the drive shaft, and the first return spring moves the valve shaft in the valve opening direction to move the second return spring in the second direction. Return spring urges the valve shaft to rotate in the valve closing direction. For this reason, since the first and second return springs that urge the valve shaft in the valve opening direction and the valve closing direction are used, the valve opening position of the intake throttle valve when the drive motor is not operating is adjusted by the urging force. By changing it, it can be set to any intermediate opening position from fully open to fully closed. Therefore, it is possible to provide an intake throttle valve that is normally opened at a valve opening position corresponding to the required intake flow rate.

In addition, since the first and second return springs have different spring constants, the torque characteristics that can be generated when both return springs are urged to the valve shaft are defined by the slope of the torque characteristic with respect to the valve shaft rotation angle. There are 2 stages 2
Step characteristics can be obtained. Among the two-stage characteristics, when the inclination of the torque characteristic is large (the amount of change in torque with respect to the valve shaft rotation angle is large), the variation of the rotation angle with respect to the driving torque can be reduced, and the resolution of the valve shaft rotation angle can be improved. . Thereby, when controlling the valve shaft rotation angle by feedback control, controllability can be improved.

Furthermore, the resolution of the valve shaft rotation angle can be improved only by setting the characteristics of the return spring to two-stage characteristics without using a reduction gear, so that the intake throttle valve can be reduced in size with a simple configuration, in other words. An intake throttle device that can be reduced in size with a simple configuration can be provided.

Therefore, while providing an intake throttle valve that is normally opened at a valve opening position corresponding to the required intake flow rate, the resolution of the valve shaft rotation angle can be improved, and the size can be reduced with a simple configuration.

The torque characteristic that can be generated by biasing the first and second return springs to the valve shaft becomes zero at a predetermined intermediate opening position as described in claim 2. It is desirable that the spring constant on the side that rotates the valve shaft in the valve closing direction from this intermediate opening position is larger than the spring constant on the side that rotates the valve shaft in the valve opening direction. Thus, an intake throttle valve that is normally opened at the intermediate opening position can be provided. In addition, as described in this embodiment, when it is desired to prevent engine vibration by reducing the intake flow rate after the fuel is cut off, the spring constant on the side to be rotated in the valve closing direction is increased, that is, the torque change amount with respect to the valve shaft rotation angle Can be increased, so that the resolution of the valve shaft rotation angle can be improved, and the intake flow rate can be controlled accurately.

According to the third aspect of the present invention, the first and second return springs can be arranged on the valve shaft in series in the axial direction.

According to the fourth aspect of the present invention, in the characteristics of the valve shaft opening of the intake throttle valve and the intake flow rate, the flow rate with respect to the rotation angle in the range from the fully closed position to the intermediate opening position which is the normally open angle position. It is suitable for an intake throttle device in which the amount of change is large and the amount of change in flow rate with respect to the rotation angle gradually decreases in the range from the intermediate opening position to the fully open position.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to an intake throttle device of a diesel engine using the intake throttle device of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view illustrating a configuration of an intake throttle device according to an embodiment of the present invention.
FIG. 2 is a diagram showing torque characteristics that can be generated with respect to the valve shaft opening of a return spring that urges the valve shaft in the intake throttle valve in FIG. 1, and shows a balance relationship with the drive torque of a drive motor. FIG. FIG. 3 is a characteristic diagram showing a relationship between the valve shaft opening of the intake throttle valve and the intake flow rate in FIG.

As shown in FIG. 1, the intake throttle device 1 includes an intake throttle valve 10, a drive motor 20 for driving a valve shaft 12 of the intake throttle valve 10, and control means 50 for controlling the drive motor 20. It is composed of

(Structure of the intake throttle valve)
A valve housing 11, a valve shaft 12 rotatably disposed in the valve housing 11, and an intake passage 11 a fixed to the valve shaft 12 and formed in the valve housing 11.
And a valve element 13 for making the opening area of the intake passage 11a variable.

As shown in FIG. 1, the valve housing 11 has a substantially cylindrical shape at the front and rear, and has an intake passage 11a formed therein. Left and right walls 11b1 of the valve housing 11,
11b2 rotatably supports the valve shaft 12. A drive motor for driving the valve shaft 12 is fixed to one wall 11b1 supporting the valve shaft 12, and a biasing means 30 for biasing the valve shaft 12 in the rotational direction is provided on the other wall 11b2. ing.

The details of the urging means 30 for urging the valve shaft 12 in the rotational direction will be described later.

The valve shaft 12 is a common shaft of the intake throttle valve 10 and the drive motor 20, as shown in FIG. In addition,
The valve shaft 12 may be configured to rotate the valve body 13 of the intake throttle valve 10 by the rotation shaft of the drive motor 20, and may be integrally engaged with the rotation shaft.

Hereinafter, in the present embodiment, the valve shaft 12 will be described as a common shaft of the intake throttle valve 10 and the drive motor 20. The drive motor 20 for rotatably holding the valve shaft 12 and the bearing members 19 and 29 for rotatably holding the valve shaft 12 are provided at both ends of the valve housing 11, so that the valve shaft 12 itself is rotated. It is possible to make the generated valve shaft torque substantially zero.

The valve body 13 has a well-known valve body shape that opens and closes the intake passage 11a in the valve housing 11 by rotation of the valve shaft 12, and can change the opening area of the intake passage 11a from a fully closed position to a fully open position. Having.

(Structure of Drive Motor) The drive motor 20
By rotating the valve body 13 of the intake throttle valve 10, the intake passage 11a
As long as the opening area can be variably controlled by the control means 50, the drive motor may be a stepping motor or a DC motor in addition to the torque motor shown in FIG.

Hereinafter, the torque motor applied to the embodiment of the present invention will be described. The drive motor 20 is held by the valve housing 11 and fixed to an end 12 a of the valve shaft 12 and a stator portion 21 disposed on the outer periphery of the valve shaft 12.
And a rotor 22 disposed in the vicinity of the stator 21 in the axial direction. The stator 21 has a plurality of coils 21a (four coils in the present embodiment).
As shown in FIG. The rotor 22 has an annular magnet between itself and the stator 21.

Since the drive motor 20 is feedback-controlled using the control means 50, the rotation angle (valve shaft opening position) of the valve shaft 12 is provided at the end of the drive motor 20, as shown in FIG. It is desirable to have a rotation angle sensor 40 for detecting. Thus, the rotation angle of the valve shaft 12 can be controlled at an absolute position without energizing the drive motor 20 and estimating the rotation angle.

(Configuration of Control Means) An electronic control unit capable of feedback-controlling the rotation angle of the drive motor 20 may be used. The control means (hereinafter referred to as ECU) 50 includes a CPU, ROM, RAM, and the like (not shown). It is configured as a microcomputer at the center. Also, this EC
The detection signal of the rotation angle sensor 40, the accelerator opening signal 91, the signal 92 representing the battery voltage, and the like are input to U50. The ECU 50 also transmits a drive signal to the drive motor 20 to control the intake flow rate by changing the opening of the valve shaft 12 of the intake throttle valve 10 in accordance with the operation state of the diesel engine, and transmits the drive signal to the valve of the drive motor 20. Axis 1
2 is controlled.

The intake throttle device 1 having the above configuration is
In a mounted state of a vehicle or the like, air sucked through the air filter 200 on the upstream side of the intake air is introduced into an intake passage 11 a formed in the valve housing 11 of the intake throttle valve 10. The flow rate of the introduced intake air is adjusted in accordance with the position of the valve shaft opening of the valve body 13 whose opening area is made variable by the drive motor 20. The metered intake air is led out to the engine 300 airtightly arranged on the downstream side of the intake throttle valve 10, and is mixed with fuel supplied from a fuel injection valve (not shown) in the combustion chamber to perform compression ignition. Is done.

Here, details of the urging means 30 for urging the valve shaft 12 in the rotational direction, which is a feature of the embodiment of the present invention, will be described below.

As shown in FIG. 1, the urging means 30 includes a first return spring 3 for urging the valve shaft 12 in the valve opening direction.
1 and a second return spring 32 that urges the valve shaft 12 in the valve closing direction.

The first return spring 31 includes a winding portion 31a and both ends 31b and 31c.
1b is locked to the wall 11b2 of the valve housing 11, and the other end 31c is connected to the valve shaft 12 with the nut 8 as shown in FIG.
It is locked to a cylindrical portion 33 fixed by a fixing member such as 0. The second return spring 32 includes a winding part 32a and both ends 32b and 32c. One end 32b is locked to the cylindrical part 33, and the other end 32c is
The first and second return springs 31 and 32 are engaged with a cover 34 fixed to the wall 11b2 of the valve housing 11 so as to sandwich the first and second return springs 31 and 32 therebetween. Note that the wall 11b2 that accommodates the first and second return springs 31 and 32 and the cover 3
4, and the cylindrical portion 33, each of the cylindrical outer peripheral surface 11b2C therein, is formed to 33C _1, 33C _2, 34C,
The first and second return springs 31 and 32 are rotatably fitted.

The torque characteristics that can be generated by the urging means 30 urging the valve shaft 12, ie, the torque characteristics that can be generated by the first and second return springs 31 and 32 urging the valve shaft 12, are as follows. It has the torque characteristics shown in FIG.

In the characteristic diagram shown in FIG. 2, the horizontal axis represents the valve shaft opening θ of the valve shaft 12, and the vertical axis represents the first and second return springs 31 and 32 of the urging means 30 when the valve shaft is opened. Represents the torque Tr applied to the valve shaft 12 according to the degree θ. Here, this torque characteristic Tr is indicated by a double line as shown in FIG. 2 and represents the width of hysteresis caused by the return spring structure. In the torque characteristics, the torque for rotating the valve shaft 12 in the valve opening direction is expressed as positive, and the torque for rotating the valve shaft 12 in the valve closing direction is expressed as negative.

As shown in FIG. 2, the torque characteristic T of the first return spring 31 for urging the valve shaft 12 in the valve opening direction is shown.
r1 and the torque characteristic Tr2 of the second return spring 32 biased in the valve opening direction are determined by a predetermined intermediate opening position θN.
The biasing force of each of the first and second return springs 31 and 32 is set so that the torque becomes zero. Also, the spring constant K of the first return spring 31
1 is set to be larger than the spring constant K2 of the second return spring 32. In other words, the spring constant K1 for rotating the valve shaft 12 in the valve closing direction from the predetermined intermediate opening position θN is larger than the spring constant K2 for rotating the valve shaft 12 in the valve closing direction. .

Next, the operation of the intake throttle device of the present invention will be described below. Since the operation of adjusting the intake flow rate of the intake throttle device 1 has been described above, the operation of the urging means 30 having the above-described configuration will be described.

The first and second return springs 31 and 32 which are the urging means 30 have different spring constants. The spring constant K1 of the first return spring 31 is different from the spring constant of the second return spring 32. Since it is set to be larger than K2, the predetermined intermediate opening position θ shown in FIG.
On the side that rotates the valve shaft 12 in the valve closing direction from N, the resolution with respect to the rotation angle of the valve shaft 12 can be improved.

That is, the conventional valve shaft 12 shown in FIG.
The first and second return springs having different spring constants are used as compared with the torque characteristics of the return spring that urges the valve shaft 12 in the valve opening direction, so that the valve shaft 12 rotates in the valve closing direction from the intermediate opening position θN. In this case, the spring constant K1 (in other words, the amount of change in torque with respect to the valve shaft opening θ) is increased. Accordingly, in the present embodiment, as shown in FIG. 2, the rotation angle difference Δθ2 due to the closing torque TmC for rotating the valve shaft 12 of the drive motor 20 in the valve closing direction is compared with the rotation angle difference Δθ1 according to the conventional configuration shown in FIG. (Δθ1
> Δθ2), the variation in the rotation angle of the valve shaft 12 with respect to the closing torque of the drive motor 20 can be reduced. Thereby, when controlling the valve shaft rotation angle θ by feedback control, controllability can be improved. That is, E
In the CU 50, the valve shaft angle of the valve shaft 12 is feedback-controlled in accordance with the valve shaft opening position θ detected by the rotation angle sensor 40. Therefore, the ECU 50 receives the accelerator opening detection signal 91 and the like. Thus, it is possible to determine the operating state of the engine and control the intake air flow according to the operating state of the engine. Therefore, when the engine is stopped, the fuel supply from the fuel injection valve is shut off, and then the intake flow rate of the intake throttle device 1 is reduced to prevent engine vibration.

Further, similarly to the conventional configuration, the intermediate opening position θ
N allows the valve body 13 to be normally opened, and furthermore, by setting the respective urging forces of the first and second return springs 31 and 32, the predetermined intermediate opening position θN that is normally opened can be set to an arbitrary valve. The shaft opening θ can be set. Therefore, it is possible to provide the intake throttle device 1 including the intake throttle valve 10 which is normally opened at the valve shaft opening θ corresponding to the required intake flow rate.

Further, as a means for improving the resolution of the rotation angle of the valve shaft 12, a reduction gear may be mounted on the drive motor 20 for driving the intake throttle valve 10, but if the reduction gear is mounted on the intake throttle 1, However, the physique of the device becomes large. On the other hand, in the present embodiment, the torque characteristic Tr of the urging means 30 is changed to the two-stage characteristic, and
It is possible to improve the resolution of the rotation angle of
Compared to the case where the reduction gear is mounted, the configuration of the intake throttle device 1 is simplified, and the size can be reduced.

(Modification) As an intake throttle device of a modification,
It is preferable to use the intake throttle valve 10 having the relationship between the valve shaft opening θ and the intake flow rate AF as shown in FIG.

That is, the spring constant K2 for rotating the valve shaft 12 in the valve closing direction is smaller than the spring constant K1 for rotating the valve shaft 12 in the valve opening direction from the predetermined intermediate opening position θN. In the present embodiment, which is an intake throttle device provided with the urging means 30, as shown in FIG. 3, on the opening side higher than the intermediate opening position θN, the amount of change of the intake flow rate AF with respect to the valve shaft opening θ becomes smaller. Therefore, it is possible to reduce the variation of the intake flow rate difference ΔAF with respect to the rotation angle difference ΔθAF.

For this reason, if the intake throttle device 1 provided with the intake throttle valve 10 having the relationship between the valve shaft opening θ and the intake flow rate AF as described above is used in a diesel engine employing EGR, Large EG by reducing intake flow
R can be controlled accurately.

In the present embodiment, the first and second return springs 31 and 32 arranged in series in the axial direction of the valve shaft 12 as the urging means 30 have been described. The first and second return springs 31 and 32 having different spring constants may be arranged in the radial direction with respect to the valve shaft 12 as long as it has a two-stage characteristic that is a two-stage characteristic.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating a configuration of an intake throttle device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a torque characteristic that can be generated with respect to a valve shaft opening of a return spring that urges a valve shaft in the intake throttle valve in FIG. 1, and is a balance relationship with a drive torque of a drive motor. FIG.

FIG. 3 is a characteristic diagram illustrating a relationship between a valve shaft opening of an intake throttle valve and an intake flow rate in FIG. 1;

FIG. 4 is a diagram illustrating torque characteristics that can be generated with respect to the valve shaft opening of a return spring that urges a valve shaft in an intake throttle valve used in an intake throttle device having a conventional configuration, and illustrates a drive torque of a drive motor. FIG. 7 is a characteristic diagram illustrating a balance relationship with the graph.

[Explanation of symbols]

Reference Signs List 1 intake throttle device 10 intake throttle valve 11 valve housing 11a intake passage 12 valve shaft 13 valve body 20 drive motor 30 biasing means 31, 32 first and second return springs 33 cylindrical portion 34 cover 40 rotation angle sensor 50 control means (ECU) Tr, (Tr1, Tr2) Torque that can be generated by urging the urging means 30 against the valve shaft 12 (torque of the first return spring, torque of the second return spring) θ Valve shaft opening (rotation) Angle) Δθ Rotation angle difference θN Predetermined intermediate opening position (valve shaft opening position at which the valve body of the intake throttle valve is normally open) ΔAF, ΔθAF Intake flow rate difference, rotation angle difference corresponding to intake flow rate difference

Claims (4)

[Claims] 1. An intake throttle device comprising: an intake throttle valve that opens and closes an intake passage; a drive motor that drives a valve shaft of the intake throttle valve; and control means that controls the drive motor. One end has a different spring constant from each other,
A second return spring is provided, and the first return spring is provided.
Wherein the return spring urges the valve shaft in the valve opening direction, and the second return spring urges the valve shaft in the valve closing direction. 2. A torque characteristic that can be generated by biasing the first and second return springs to the valve shaft is zero at a predetermined intermediate opening position, and the intermediate opening position The spring constant on the side that rotates the valve shaft in the valve closing direction from the intermediate opening position is larger than the spring constant on the side that rotates the valve shaft in the valve opening direction from the intermediate opening position. Item 7. An intake throttle device according to item 1. 3. The intake throttle device according to claim 1, wherein the first and second return springs are arranged in series in an axial direction. 4. The characteristics of the valve shaft opening degree and the intake flow rate of the intake throttle valve are such that when the valve shaft is rotated from a fully closed direction to a fully opened direction,
From the fully closed position to the intermediate opening position, the amount of change in the flow rate with respect to the rotation angle is large, and from the intermediate opening position to the fully open position, the amount of change in the flow rate with respect to the rotation angle is reduced. 4. The intake throttle device according to claim 2, wherein: