JPH0742629A - Structure of EGR valve - Google Patents

Abstract

(57) [Summary] [Object] In an electric type EGR valve, even if the EGR valve is in an open state, the EGR gas to the intake system is shut off to smoothly start the engine. At the same time, the life of the movable mechanism portion of the step motor of the EGR valve is extended. Therefore, the present invention is provided with the EGR gas cutoff control mechanism 42 that cuts off the supply of the EGR gas even when the valve spindle 48 of the electric type EGR valve 40 is in the open operation state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an EGR valve, and more particularly, to an EGR valve which can smoothly start an engine and prolong the life of a movable mechanism portion of a step motor for opening and closing a valve spindle. Regarding the structure.

[0002]

2. Description of the Related Art Some vehicle engines are equipped with an EGR device that recirculates a part of exhaust gas, so-called EGR gas, to the intake system as air as an inactive part.

As shown in FIG. 4, this EGR device uses an EGR gas inlet 206 to supply EGR gas, which is a part of exhaust gas discharged from the engine 202 to an exhaust passage 204, to an EGR gas inlet 206.
It is introduced into the passage 208 and then recirculates from the EGR gas outlet 210 to the intake passage 212 of the intake system. In the middle of the EGR passage 208, an electric EGR valve 214 that controls the supply and disconnection of EGR gas to the intake system is provided.

The EGR valve 214 includes a step motor 220 that operates in a valve case 216 in accordance with a current-carrying state from a control means (ECM) 218, and a valve spindle that is reciprocated in the axial direction while being rotated by the step motor 220. 222 and EGR passage 208
Valve body 22 of the valve spindle 222 for opening and closing
4 and the valve spindle 222.
The position sensor 228 and the like for detecting the position of

A structure of such an EGR valve is disclosed in Japanese Utility Model Laid-Open No. 58-44465. The one disclosed in this publication has a diaphragm that is displaced by a negative pressure of an intake system of an internal combustion engine, an axis that is perpendicular to the diaphragm, is movably held in the axial direction, and has a valve at one end. It has a valve shaft, an exhaust gas intake port that is opened and closed by displacement of the valve element in the valve axis direction, and an exhaust gas discharge port that communicates with the intake system of the engine, and the valve shaft is rotatable about its axis. The end is supported by a diaphragm, and an impeller is attached to the valve shaft in the exhaust suction port.

[0006]

However, the electric E
In the case of the GR valve, when the power to the step motor is cut off during the opening operation of the valve spindle, the opening / closing hole is opened and the EGR gas is introduced into the intake system when the engine is started by turning the ignition key on next. Therefore, there is an inconvenience that it is difficult to start the engine. To eliminate this inconvenience, for example, in a system where the return spring returns the valve spindle to its original position when the power to the step motor is cut off, the valve spindle is returned to the closed operation state after the power is cut off. It is conceivable that the energization of the step motor will be cut off after that, but it is necessary to increase the driving force for the return spring, which causes a problem that the energization of the step motor from the control means (ECM) is always required.

[0007]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention is an electric motor which controls the supply and disconnection of EGR gas to the intake system by opening and closing the valve spindle according to the energization state of the step motor. In the structure of the EGR valve of the type E, the valve spindle is operated to cut off the supply of EGR gas even when the valve spindle is in an open state.
A feature is that a GR gas cutoff control mechanism is provided.

[0008]

According to the structure of the present invention, in controlling the amount of EGR gas during the operation of the engine, the EGR gas cutoff control mechanism is in an open state and the amount of EGR gas is controlled by the valve spindle of the EGR valve. Then, when the ignition key is turned off, the EGR gas cutoff mechanism is in the closing operation state. Therefore, for example, during deceleration operation, EGR
When the valve needs to be closed rapidly, it is not necessary to operate the EGR valve in the fully closed state each time, and the EGR gas can be blocked by the EGR gas blocking mechanism. As a result, the EGR gas to the intake system can be shut off even when the EGR valve is in the open state, so that the engine can be started smoothly and the life of the movable mechanism portion of the step motor of the EGR valve can be extended. EG, and without operating the step motor
The R gas can be suddenly shut off, and the driving force of the step motor can be set to a small value, whereby the size and weight can be reduced and the price can be reduced.

[0009]

Embodiments of the present invention will be described in detail and specifically with reference to the drawings. 1 and 2 show an embodiment of the present invention. 1, 2 is an engine, 4 is a cylinder block, 6 is a cylinder head, 8 is a cylinder head cover, 10 is a piston, 12 is a combustion chamber, 14 is an intake port, 16 is an exhaust port, 18 is an intake manifold, and 20 is two. A speed type carburetor, 22 is an intake passage, 24 is an intake valve, 26 is an exhaust manifold, 28 is an exhaust passage, and 30 is an exhaust pipe.

The engine 2 is provided with an EGR device 32. The EGR device 32 introduces the EGR gas, which is a part of the exhaust gas in the exhaust passage 28, from the EGR gas inlet 34 formed in the exhaust manifold 26 into the EGR passage 36, and then the EGR gas outlet 38 formed in the intake manifold 18.
From the air to the intake passage 22.

An EGR valve 40 for controlling the supply and disconnection of EGR gas to the intake passage 22 side and an EGR gas cutoff control mechanism 42 integrally formed with the EGR valve 40 are provided in the middle of the EGR passage 36. Therefore, the EGR passage 36 includes the first EGR passage 36-1 between the EGR gas inlet 34 and the EGR valve 40, and the second EGR passage 36-2 between the EGR valve 40 and the EGR gas outlet 38.

As shown in FIG. 2, the EGR valve 40 includes a valve spindle 48 which is reciprocally held by a spindle holder 46 in a valve case 44, and an energized state from a control means 86 which will be described later. A step motor 50 for opening and closing while rotating 48, that is, a step motor 50 for axially moving, and a connecting body 54 so that the valve body portion 52 of the valve spindle 48 is brought into contact with and separated from one side.
It has an opening / closing hole 56 formed in the above and a position sensor 58 for detecting the position of the valve spindle 48. In addition, in the valve case 44, on the valve body 52 side of the valve spindle 48, the first EGR is provided on one side of the opening / closing hole 56.
A first gas flow passage 60 communicating with the passage 36-1 and a second gas flow passage 62 communicating with the second EGR passage 36-2 on the other side of the opening / closing hole 56 are formed.

The EGR gas cutoff control mechanism 42 includes a sub-spindle 68 that is reciprocally held by a sub-spindle holder 66 in a sub-valve case 64 that is connected to the valve case 44 of the EGR valve 40, and a sub-spindle. A solenoid 72 held by a holder 66 and a solenoid case 70, and a spring 74 for axially urging the sub-valve spindle 68 in the solenoid case 70. The sub-valve spindle 68 opens and closes the other side of the opening / closing hole 56 by the sub-valve body portion 76 provided at the tip when reciprocating. The end portion of the sub valve case 64 is closed by a cover 78.

The motor side lead wire 80 connected to the step motor 50, the position side lead wire 82 connected to the position sensor 58, and the solenoid lead wire 84 connected to the solenoid 72 are controlled by a control means (E).
CM) 86. A battery 88 communicates with the control means 86.

The control means 86 controls the valve spindle 48 of the EGR valve 40 to open, that is, the opening / closing hole 56.
Even when the EGR gas is opened, the EGR gas cutoff control mechanism 4 is used to cut off the supply of the EGR gas to the intake passage 22 side.
2 is operated, that is, the sub-valve spindle 68 opens and closes the opening 5
6 is closed.

That is, the EGR gas to the intake passage 22 side is
The EGR valve 40 serves as a main, and the EGR gas cutoff control mechanism 42 serves as a sub.

Next, the operation of this embodiment will be described.

To control the amount of EGR gas while the engine 2 is operating, the EGR gas cutoff control mechanism 42 is in an open state,
That is, the sub valve spindle 68 opens the opening / closing hole 56, and the valve spindle 48 of the EGR valve 40
The EGR gas amount is controlled by the operating state of. Then, when the ignition key is turned off, the EGR gas cutoff control mechanism 42 is in a closing operation state, that is, the sub valve spindle 68 closes the opening / closing hole 56. Therefore, for example, when it is necessary to close the EGR valve 40 rapidly during deceleration operation, the valve spindle 4 of the EGR valve 40
EGR does not have to be operated in a fully closed state each time.
The EGR gas can be shut off by the sub valve spindle 68 of the gas shutoff control mechanism 42.

As a result, since the EGR gas to the intake system can be shut off even when the EGR valve 40 is in the opening operation state, the EGR gas is shut off at the time of starting the engine 2 to easily start the engine 2. In addition to the above, the life of the movable mechanism portion of the step motor 50 of the EGR valve 40 can be extended, and the EGR gas can be suddenly shut off without operating the step motor 50. The force can be set to be small, which enables reduction in size and weight as well as cost reduction.

Further, since the EGR valve 40 and the EGR gas cutoff control mechanism 42 are integrally formed, it can be made compact in spite of providing two assemblies.

FIG. 3 shows another embodiment of the present invention.

As shown in FIG. 3, the EGR passage 10 connecting the exhaust passage 104 and the intake passage 106 of the engine 102.
In the middle of 8, the EGR gas cutoff control mechanism 110 and the EGR valve 112 are separately provided from the exhaust passage 104 side. EGR gas cutoff control mechanism 110 and EGR valve 1
Although 12 is a separate body, it has substantially the same structure as that shown in FIG.

The solenoid side lead wire 114 connected to the EGR gas cutoff control mechanism 110, the motor side lead wire 116 and the position side lead wire 118 connected to the EGR valve 112 are connected to the control means 120. Also,
The battery 122 communicates with the control means 120.

According to another embodiment, the EGR valve 1
Since the 12 and the EGR gas cutoff control mechanism 110 can be handled separately, the degree of freedom of the installation location is large, and if one fails, only one can be removed and repaired or replaced. The handling becomes simple.

[0025]

As is apparent from the above detailed description, according to the present invention, the EGR gas shutoff is operated to shut off the EGR gas supply even when the valve spindle of the electric EGR valve is in the open operation state. By providing the control mechanism, the EGR gas to the intake system can be shut off even when the EGR valve is in the opening state, so that the engine can be started smoothly and the movable mechanism of the step motor of the EGR valve can be performed. The life of the part can be extended.

Even if the step motor is not operated,
The EGR gas can be suddenly cut off, and the driving force of the step motor can be set to a small value.
The weight can be reduced and the price can be reduced.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an EGR device.

FIG. 2 is an enlarged cross-sectional view of an EGR valve and an EGR gas cutoff control mechanism that are integrally provided.

FIG. 3 is a system configuration diagram of a separate EGR valve and EGR gas cutoff control mechanism.

FIG. 4 is a system configuration diagram of a conventional EGR device.

[Explanation of symbols]

 2 engine 22 intake passage 28 exhaust passage 32 EGR device 36 EGR passage 40 EGR valve 42 EGR gas cutoff control mechanism 48 valve spindle 50 step motor 68 sub valve spindle 72 solenoid

Claims (3)

[Claims] 1. A structure of an electric type EGR valve for controlling opening / closing of a valve spindle according to an energized state of a step motor to control supply / disconnection of EGR gas to an intake system,
Even when the valve spindle is in the open state, EG
An EGR valve structure comprising an EGR gas cutoff control mechanism which is operated to cut off the supply of R gas. 2. The EGR gas cutoff control mechanism is provided with the E
The structure of the EGR valve according to claim 1, wherein the structure is integrally formed with the GR valve. 3. The EGR gas cutoff control mechanism is provided for the E
An EGR valve structure characterized in that it is provided in the EGR passage separately from the GR valve.