JPH01125549A - Exhaust gas reflux controlling valve for internal combustion engine - Google Patents

Abstract

PURPOSE:To dispense with a temperature sensing valve and shorten a negative pressure pipe by providing a shape memorizing element for urging an elastic member in the opposite direction to the valve closing direction in warming up an internal combustion engine to forcibly close a valve body with said element in cooling down said engine. CONSTITUTION:A cooling water path 3 is additionally provided in an intake pipe 2 provided with a throttle valve 1, while an EGR path 4 communicating to an exhaust pipe is connected to the intake pipe. In the EGR path 4 is provided with an EGR valve 5. Then, the EGR valve 5 is provided with an elastic member 8 for normally pressing a valve body 6 in the direction of a valve seat 10, a diaphragm device 70 for urging the valve body 6 in the opposite direction to a valve seat 8 by negative pressure introduced from a port 2a opening to the intake pipe 2 through a path 15 and a shape memorizing element 11 for urging the elastic member 8 in the opposite direction to the pressing direction in warming up an internal combustion engine. In cooling said engine, the valve body 6 is forcibly closed by said element 11.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides an exhaust gas recirculation device that suppresses the generation of nitrogen oxides by recirculating the exhaust gas of an internal combustion engine to the intake system of the engine; In particular, the present invention relates to an exhaust gas recirculation control valve that takes into account the recirculation of exhaust gas during low-temperature engine operation.

[Prior Art] Figure 4 is a sectional view showing a conventional exhaust gas recirculation control valve installed in an internal combustion engine. In the figure, (1) is a throttle valve, (2) is an intake pipe, and (3) is a throttle valve. is the cooling water passage,
(4) is an exhaust gas recirculation passage that communicates with an exhaust pipe (not shown), (5) is an exhaust gas recirculation control valve (hereinafter referred to as EGR pulp) that controls the amount of recirculation of exhaust gas, and (6) is an exhaust gas recirculation passage that communicates with an exhaust pipe (not shown). The valve body is connected to a responsive diaphragm (7) and is pressed in the direction of the valve seat (10) by a spring (8) as an elastic member. (9) is a case that forms a negative pressure chamber together with the diaphragm (7), and the diaphragm assembly W is formed by the diaphragm (7) and the case (9).
(70) - (2a) and (9m) are both negative pressure boats.

In addition, the negative pressure passage (between the negative pressure boat (2m) and (9a)
15) A temperature sensing valve (14) is provided on the cooling water passage (3).
) is sensed to open and close the negative pressure passage (15).

The operation of the normal EGR valve (5) will be explained next.The valve (6) is pressed against the valve seat (10) by the force of the spring (8), and the exhaust gas recirculation passage (4) is closed. Negative pressure is generated in the intake pipe (2) due to certain operating conditions, and the negative pressure is introduced from the ports (2a) and (9a) into the negative pressure chamber formed by the diaphragm (7) and the case (9). , a force is generated in the direction in which the diaphragm (7) is pulled upward in the figure, and the spring (8)
When the pressure exceeds the pressing force, the valve (6) connected to the diaphragm (A) is pulled up and opened.

However, if exhaust gas is recirculated when the engine is cold, startability and drivability will deteriorate.
) and EGR valve (5) negative pressure boat (2m) (9m)
By installing a temperature sensing valve (14) in the normal negative pressure (15) between and installing this temperature sensing valve (14) on the wall of the cooling water passage (3), it is possible to The temperature sensing valve (14) closes the negative pressure passage (15) so that the EGR valve (5) does not open.

[Problems to be solved by the invention] The conventional EGR valve has a separate temperature sensing valve (
14), and as a result, the piping of the negative pressure passage (15) becomes long, and there are problems such as opening work and installation work for installing the temperature sensing valve (14).

This invention was made in order to solve the problems of the conventional device described above, and it is an E
The purpose is to obtain GR pulp.

[Means for Solving the Problems] The EGR valve according to the present invention includes a valve body and a valve seat provided so as to be able to open and close a passage used as a recirculation path of exhaust gas to an engine, and the valve body is connected to the valve body. an elastic member that constantly presses in the direction of the seat; a diaphragm device that biases the valve body in the opening direction by the negative pressure generated by the engine; Equipped with a shape memory element that biases the member, when the engine is at low temperature,
The valve body is configured to close regardless of the negative pressure generated by the engine.

[Function] The shape memory element of the present invention maintains a softened state when the engine is cold, does not cause the valve body to open, and when the engine is warm, the shape memory element returns to its shape by the force that causes it to move in the opposite direction to the direction in which the elastic member is pressed. When the elastic member is pressed in the direction and negative pressure is applied to the diaphragm, the valve body is opened in response to the negative pressure.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
In the figures and FIG. 2, the valve body (6) integrally connects the diaphragm (7) and the holders (12a) (IZb) installed on both sides of the diaphragm (7) at one end thereof. ) and the case (9).
) is sandwiched between the springs (8) as elastic members.

Further, a shape memory coil (11) as a shape memory element is installed on the side opposite the spring (8) and the diaphragm (7) via a holder (12b). This shape memory coil (11) softens at low temperatures and does not exhibit elasticity, but at temperatures above a certain transformation point it works as an elastic body to return to its original shape, and the force is applied in the opposite direction to the pressing direction of the spring (8>). is generated, and the spring (8) pushes the valve body (6) against the valve seat (10
) acts to reduce the pressing force in the direction. In addition,
(13) is a bearing that receives the sliding portion of the valve body (6).

The force of the spring (8) that presses the valve body (6) is applied to the diaphragm (A) even when negative pressure in the intake pipe is applied to the diaphragm (A) under any operating conditions when the engine is at a low temperature, so that the valve does not open. By setting as follows, EGR when cold
Shape memory coil (11) when the valve atmosphere temperature is low
Because it is softened, it does not exhibit any force contrary to the pressing force of the spring (8), and even if negative pressure in the intake pipe is applied to the diaphragm (7) under any operating conditions, the valve will open and the exhaust gas will recirculate. After warm-up, where exhaust gas recirculation does not affect driveability, the ambient temperature is high, and the transformation point of the shape memory coil (11) should be set at that temperature. The shape memory coil (11
) exhibits elasticity due to the force of returning to its shape, and the spring (8
A force is applied in the opposite direction to the pressing force of
By applying this voltage, normal opening/closing valve operation is performed.

In the above embodiment, the shape memory coil (11) is caused to return to its shape depending on the ambient temperature of the EGR valve (5). (5) In an EGR valve in which an engine cooling water passage is formed in the main body, it is also possible to cause the shape memory coil to return to its shape depending on the engine cooling water temperature.

FIG. 3 shows another embodiment of the present invention in which the shape memory coil (11) is activated depending on the temperature of the cooling water. The water passage (3) is provided close to the shape memory coil (11). Therefore, this embodiment has the advantage that the thermal response of the shape memory element (11) can be made faster.

It should be noted that the present invention is of course not limited to the embodiments described above, and various modifications and changes are possible.

[Effects of the Invention] As described above, according to the present invention, a valve body and a valve seat are provided to open and close a passage used as a recirculation path for exhaust gas to the engine, and the valve body is connected to the valve seat. a diaphragm device that biases the valve body in the valve opening direction by negative pressure generated by the engine; and a diaphragm device that biases the valve body in the valve opening direction by negative pressure generated by the engine; The valve element is equipped with an energizing shape memory element, and is configured to close the valve element when the engine is at low temperature, regardless of the negative pressure generated by the engine.Therefore, there is no need to provide a separate temperature range sensing valve, and the negative pressure is reduced. This has significant effects, such as requiring shorter piping to obtain the same.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram showing a state in which an exhaust gas recirculation control valve (EGR valve) according to an embodiment of the present invention is installed in an internal combustion engine, and FIG. 2 is a cross-sectional diagram showing the above-mentioned EGR valve.
FIG. 3 is a sectional view showing an EGR valve according to another embodiment of the present invention, and FIG. 4 is a sectional view showing a conventional device.
In the figure, (4) is the exhaust gas recirculation path, (5) is the exhaust gas recirculation control valve (EGR valve), (6) is the valve body, and (1) is the exhaust gas recirculation control valve (EGR valve).
0) is a valve seat, (70) is a diaphragm device, (8) is an elastic member (spring), and (11) is a shape memory element. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. 1st Figure 5 Heel tip force, 11 circles, EαR 6 19863 March 1st

Claims (1)

[Claims] A valve body and a valve seat provided to open and close a passage used as a recirculation path of exhaust gas to the engine, an elastic member that constantly presses the valve body in the direction of the valve seat, and a negative pressure generated by the engine. Therefore, the valve body is provided with a diaphragm device that biases the valve body in the valve opening direction, a shape memory element that biases the elastic member in a direction opposite to the pressing direction of the elastic member when the engine is warm, and a shape memory element that biases the elastic member in a direction opposite to the pressing direction of the elastic member when the engine is cold. An exhaust gas recirculation control valve for an internal combustion engine, characterized in that the valve body is closed regardless of the negative pressure generated by the engine.