JP2001123890A - Exhaust gas recirculating valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of noise without having to reduce the moving speed of a valve element during a closing stroke. SOLUTION: Upper and lower throttle parts 32 and 33 are protruded from a first cylinder chamber 18, to reciprocate a valve stem 7 coupled to a valve element 6 to open and close the valve port 4 of an EGR valve 1 and a first piston 21, and a second cylinder chamber 24 and a second piston 28. The upper throttle part 32 is formed in a manner to be inserted in the opening part 15a of a first port 15, to feed air to the upper side of the first piston 21 of the first cylinder chamber 18, and the lower throttle part 33 is formed in a manner to be inserted in the opening part 31a of the communication passage 29 of the second piston 28. Thus, the throttle part reduces the speed of a piston, by throttling a flow of fluid in the vicinity of the terminal point of a closing stroke by the valve spring of the piston and prevents the generation of strike noise as a result of the piston colliding with a cylinder chamber. Since the stroke speed of the piston is set to a high value, the generation of black smoke during pedaling of an accelerator is prevented from occurring through prevention of the increase of a closing stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation valve (Exhaust Gas Recirculation).
n Valve. Hereinafter, it is called an EGR valve. In particular, the present invention relates to a technique for reducing abnormal noise, and for example, to a technique effective for use in an EGR valve of a diesel engine for an automobile.

[0002]

2. Description of the Related Art One of the methods for reducing exhaust gas components, particularly NOx, of an automotive diesel engine is EGR.
There is a law. This means that a part of the engine exhaust gas is returned to the intake system, mixed with fresh air (intake air) and sent into the combustion chamber, thereby reducing the excess oxygen concentration of the unburnt exhaust gas and taking away combustion heat. This is a method in which the combustion temperature is reduced by an amount to suppress the generation of NOx.

[0003] The EGR method reduces the pumping loss of the engine (the work of sucking intake air by the piston), so that the mechanical efficiency of the engine can be improved accordingly. On the other hand, the thermal efficiency is reduced by the amount that the non-combustible gas deprives the combustion heat. Therefore, in order to appropriately reduce NOx without reducing the efficiency of the engine, the EGR valve is configured to be controlled by a computer, and the amount of the EGR gas is automatically adjusted according to the operating conditions (output, rotation speed) of the engine. Control is being done.

In the EGR valve, if the moving speed of the valve body when returning from the open state to the closed state is low,
It is known that, since black smoke is generated when the accelerator is depressed, the moving speed of the return stroke of the valve body should be high.

[0005]

SUMMARY OF THE INVENTION However, EGR
If the moving speed of the valve body when returning from the open state to the closed state in the valve is high, a collision sound between the valve body and the valve seat and a collision sound between the piston that operates the valve body and the cylinder chamber are generated.
In addition, since the EGR valve is automatically controlled by the computer without regard to the driver's intention, if the collision sound is loud, it may be felt as an abnormal sound.

An object of the present invention is to provide an EGR valve capable of reducing abnormal noise without significantly lowering a moving speed of a valve body from an open state to a closed state.

[0007]

A first means for solving the above-mentioned problem is to provide a valve port formed in a valve passage provided in the exhaust gas circulation path, and a valve port formed in the valve port. A valve seat formed around the valve seat, a valve body that is detachably seated on the valve seat to open and close the valve port, a valve stem connected to the valve body, and a valve spring that biases the valve stem in a seating direction. A cylinder chamber formed on an extension of the valve stem, a piston slidably fitted into the cylinder chamber and linked to the valve stem, and a side of the cylinder chamber opposite to the valve spring of the piston. And a pressure port connected to the exhaust gas recirculation valve, wherein a throttle means for restricting the flow of fluid in the pressure port is provided near an end point of a return stroke of the piston by the valve spring. Features

The second means is characterized in that the throttling means is a throttling portion provided on the opposed surface of the cylinder chamber and the piston.

A third means is that a cylinder chamber formed on an extension of the valve stem is formed in a body, and the cylinder chamber is formed with a first cylinder chamber formed inside the body and a first cylinder chamber formed inside the body. It comprises a first piston inserted into one cylinder chamber and a second cylinder formed inside the first piston, and a second piston is inserted into the second cylinder chamber. It is characterized by having been done.

According to the first and second means,
In the vicinity of the end point of the stroke in which the piston returns from the open state to the closed state due to the elastic force of the valve spring, the throttle means or the throttle section throttles the flow of the fluid in the pressure port, so that the moving speed of the piston in the cylinder chamber is reduced, As a result, it is possible to prevent the piston from colliding with the cylinder chamber and generating an impact sound. In addition, since the piston is decelerated near the stroke end point, the stroke speed of the piston during the valve closing operation can be set to a large value. As a result, the overall period of the valve closing operation of the EGR valve is shortened, and Generation of black smoke at the time of stepping can be prevented. That is, according to the above-described first and second means, abnormal noise can be reduced without significantly decreasing the closing speed of the EGR valve.

According to the third means, even when the cylinder and the piston are doubled, abnormal noise can be reduced without reducing the closing speed of the EGR valve.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

The EGR valve according to the present embodiment is provided in the middle of an exhaust gas recirculation passage (not shown) for connecting an intake passage and an exhaust passage of a diesel engine (not shown). That is, as shown in FIG. 1, the EGR valve 1 includes a valve box 2 in which a valve passage 3 is opened, and the valve passage 3 is provided in the middle of the exhaust gas circulation passage. I have. A valve port 4 is formed in the middle of the valve passage 3, and a valve holder 5 a fitted into the valve box 2 is provided around the valve port 4.
The valve seat 5 is attached via the. The valve body 6 is mounted on the valve seat 5 so as to be detached and seated.
The opening / closing degree of the valve port 4 can be increased or decreased by moving forward and backward along the axial direction (hereinafter referred to as the vertical direction) of the valve. A valve rod 7 is formed integrally with the valve body 6, and the valve rod 7 is slidably supported by a guide 8 fixed to the valve box 2.

A spring chamber 9 is formed on the opposite side of the valve box 2 from the valve port 4 (hereinafter referred to as an upper side). The spring chamber 9 accommodates a main valve spring 10 and a sub-valve spring 11. I have. The main valve spring 10 and the sub-valve spring 11 are interposed between the spring seat 12 mounted on the upper end of the valve stem 7 and the bottom surface of the spring chamber 9 in a state of energy accumulation. It is constantly biased in the direction in which it is seated on the valve seat 5. The spring seat 12 is attached to a groove provided at the tip of the valve rod 7 via a cotter 12a.

The EGR valve 1 has an actuator 13 for operating the valve body 6.
The third body 14 is assembled on the valve box 2 via a stopper 2a. A first port 15 and a second port 16 as pressure ports are respectively opened at an upper end portion and an intermediate portion of the body 14.
Compressed air (hereinafter, referred to as air) as a pressurized fluid is supplied to the 5 and the second port 16 by an electromagnetic valve (not shown) controlled by a computer. A suction / discharge port 17 is opened at the lower end of the body 14. Inside the body 14 is a first cylinder chamber 18.
The first cylinder chamber 18 communicates with a suction / discharge port 17 at a lower end thereof, which is opened concentrically with an extension of the center line of the valve stem 7.

The first cylinder chamber 18 comprises a large-diameter chamber 19 disposed on the lower side and a small-diameter chamber 20 disposed on the upper side. The first cylinder chamber 18 has a first piston formed in a cylindrical shape. 21 is slidably fitted in the vertical direction. The first piston 21 has a large diameter portion 22 and a small diameter portion 23.
The large diameter portion 22 is fitted in the large diameter chamber 19, and the small diameter portion 23 is fitted in the small diameter chamber 20.

A second cylinder chamber 24 is formed by the hollow portion of the first piston 21, and a communication port 25 is provided at an intermediate portion of the cylinder wall of the first piston 21.
The small-diameter chamber 20 and the second cylinder chamber 24 communicate with each other. At the lower end of the second cylinder chamber 24, a stopper portion 26 is provided so as to protrude radially inward on an extension of the large-diameter portion 22, and at the upper end of the second cylinder chamber 24, a cap portion 27 is provided. Is closed so as to close the upper end opening of the base plate, and is fixed by caulking.

The second cylinder chamber 24 has a second piston 28
Is fitted slidably in the up and down direction, and the lower end of the valve rod 7
It is struck by the resilience of 0,11. The horizontal passage 30 and the vertical passage 31 are provided inside the second piston 28.
Is established. Access passage 29
The horizontal passage 30 of the second piston 28 is
Contact port 25 in the state of being located at the upper limit
The vertical passage 31 is arranged at the center of the upper end surface of the second piston 28.

An upper throttle portion 32 and a lower throttle portion 33 are provided at the upper and lower end surfaces of the center of the cap portion 27 of the second cylinder chamber 24.
Are projected in the vertical direction, respectively. Upper throttle section 32
Can be inserted into an opening 15a opened downward in the vertical direction at the end of the first port 15, and the lower throttle portion 33 is inserted into the upper end opening 31a of the vertical passage 31 of the second piston 28. It is possible to do.

Next, the operation will be described.

When air is supplied to the first port 15 in the state shown in FIG.
As shown in FIG. 2, the first piston 21 is lowered together with the internal second piston 28 against the resilience of the valve springs 10 and 11, as shown in FIG. The first piston 21 stops descending by hitting a stopper 2a interposed on the upper surface of the valve box 2 which is the lower end surface of the first cylinder chamber 18.

The second piston 28 has a valve spring 1
The valve stem 7 abutted by 0 and 11 is lowered, and the valve body 6 is separated from the valve seat 5 by the stroke of the first piston 21 to open the valve port 4. In the EGR valve 1, the exhaust gas flows through the valve passage 3 as shown by the arrow A and is recirculated in accordance with the opening degree.

Next, in the state shown in FIG.
When the air is supplied to the second port 16, the air is supplied to the lower surface of the cap portion 27, which is the upper surface of the second piston 28, via the communication port 25 and the communication passage 29, and is shown in FIG. Thus, the second piston 28 is lowered against the resiliency of the valve springs 10 and 11. The second piston 28 stops descending by hitting the upper surface of the stopper portion 26.

As a result, the valve stem 7 is lowered by the stroke of the first piston 21 and the stroke of the second piston 28, and the valve body 6 is separated from the valve seat 5 by that stroke to open the valve port 4. In the EGR valve 1, the exhaust gas flows through the valve passage 3 as shown by the arrow A in accordance with the opening degree, and more exhaust gas is recirculated.

Thereafter, when the supply of air to the second port 16 is released, the second piston 28 is turned on by the valve spring 1.
It is raised by the resilience of 0,11. At this time, the air in the second cylinder chamber 24 is pushed out to the second port 16 as the second piston 28 rises. The second piston 28 contacts the lower surface of the cap portion 27 of the second cylinder chamber 24 at the upper limit position.

Here, when the second piston 28 collides with the lower surface of the cap portion 27 of the second cylinder chamber 24, an impact sound is generated. Since the blow sound is generated regardless of the driver's intention, if the blow sound is loud, the driver may feel an abnormal sound.

However, in the present embodiment, the lower throttle portion 33 is provided on the lower surface of the cap portion 27 of the second cylinder chamber 24 so as to project into the opening portion 31a of the vertical passage 31 of the second piston 28. By doing so, it is possible to prevent the second piston 28 from colliding with the lower surface of the cap portion 27 of the second cylinder chamber 24, so that it is possible to prevent the generation of an impact sound. That is, when the second piston 28 rises and reaches near the upper limit position, the lower throttle 3
3 is inserted into the opening 31a of the vertical passage 31, the amount of air pushed out from the second cylinder chamber 24 to the second port 16 is reduced, so that the rising speed of the second piston 28 is reduced. Thus, the second piston 28 is prevented from colliding with the cap portion 27 of the second cylinder chamber 24, and the impact sound is prevented from being generated.

When the supply of air to the first port 15 is released, the first piston 21 moves to the valve spring 1.
It is raised by the resilience of 0,11. At this time, the air in the first cylinder chamber 18 is pushed out to the first port 15 as the first piston 21 rises. Then, the first piston 21 contacts the lower surface of the first cylinder chamber 18 at the upper limit position.

Here, when the first piston 21 collides with the lower surface of the first cylinder chamber 18, a striking sound is generated. Because this blow sound is also generated regardless of the driver ’s will,
If the impact sound is loud, the driver may feel an abnormal sound.

In this embodiment, the first piston 21
The upper piston 32 is provided on the upper surface of the cap portion 27 which is the upper surface of the first port chamber 15 so as to be inserted into the opening 15a of the first port 15, so that the first piston 21 is provided on the lower surface of the first cylinder chamber 18. Since collision can be prevented, it is possible to prevent the generation of a blow sound. That is, when the first piston 21 rises and reaches the vicinity of the upper limit position, the upper throttle portion 32 is moved to the opening 15 a of the first port 15.
, The amount of air pushed out from the first cylinder chamber 18 to the first port 15 is reduced, so that the rising speed of the first piston 21 is reduced,
This prevents the first piston 21 from colliding with the lower surface of the first cylinder chamber 18, thereby preventing the impact sound from being generated by the collision.

When both the first piston 21 and the second piston 28 rise to the upper limit position, the valve rod 6 reaches the upper limit position as shown in FIG. Sit down and close the valve port 4. Thereby, EG
The recirculation of the exhaust gas by the R valve 1 is stopped.

When air is supplied to the second port 16 in the state shown in FIG.
Is lowered with respect to the second cylinder chamber 24, and the valve body 6 separates from the valve seat 5 by the amount corresponding to the lowering stroke to open the valve port 4. That is, in the EGR valve 1 according to the above-described configuration, four stages of operating states including the closed state are created.

As described above, according to the present embodiment, it is possible to prevent the generation of a striking sound when the EGR valve 1 is closed, thereby preventing the driver from feeling uncomfortable during the braking operation. be able to.

By the way, if the time required for the valve body 6 to separate from the valve seat 5 and open the valve port 4 until the valve body 6 is seated on the valve seat 5 to be closed is long, when the accelerator pedal is depressed. Since black smoke is generated, the speed at which the valve element 6 is seated on the valve seat 5 is preferably high. However, when the speed at which the valve element 6 is seated on the valve seat 5 is high, as described above, the collision sound of the first piston 21 with the first cylinder chamber 18 and the second cylinder chamber 24 of the second piston 28 And the sound of the collision between the valve element 6 and the valve seat 5 increases.

In this embodiment, the first piston 21
Since the second piston 28 is decelerated near the upper limit position, the rising speed of the first piston 21 and the second piston 28 during the valve closing operation can be set to be large. By increasing the moving speeds of the first piston 21 and the second piston 28 during the valve closing stroke, it is possible to prevent the overall responsiveness of the valve closing operation of the EGR valve 1 from lowering. Of black smoke can be prevented. That is, according to the present embodiment, it is possible to prevent the impact sound from being generated without significantly reducing the closing speed of the EGR valve 1.

FIG. 4 is a vibration waveform diagram obtained by measuring the vibration near the valve holder indicated by arrow B in FIG. (A) shows the case of the present embodiment, and (b) shows the case of the conventional example.
Comparing FIGS. 4A and 4B, in the case of the present embodiment, both the amplitude (magnitude of the vibration) and the duration of the vibration waveform are compared with those of the conventional example. It has been greatly reduced.

FIGS. 5A and 5B are diagrams showing the response of the EGR valve closing operation. FIG. 5A shows the case of the present embodiment, and FIG.
Indicates the case of the conventional example. According to the comparison between FIGS. 5A and 5B, it is understood that the responsiveness of the present embodiment is equivalent to that of the conventional example.

That is, according to FIGS. 4 and 5, it is understood that the EGR valve 1 according to the present embodiment can suppress or suppress the generation of an impact sound without deteriorating the responsiveness of the valve closing operation. You.

Note that the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the gist of the present invention.

For example, the EGR valve is not limited to a configuration in which four stages of operating states are created, but may be configured to create two or more stages of operating states, a closed state and an open state. Good.

The pressure fluid is not limited to the use of compressed air (air), but may be hydraulic pressure.

[0042]

According to the present invention described above, it is possible to prevent the generation of an impact sound at the time of the valve closing operation, so that the driver does not feel uncomfortable.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an EGR valve according to an embodiment of the present invention.

FIG. 2 is a partially omitted front cross-sectional view for explaining the operation.

FIG. 3 is a front cross-sectional view partially omitted.

FIGS. 4A and 4B are vibration waveform diagrams in which vibration of an EGR valve is measured as a substitute characteristic of sound, and FIG.
(B) shows the case of the conventional example.

5A and 5B are diagrams showing the response of the EGR valve closing operation, wherein FIG. 5A shows the case of the present embodiment, and FIG. 5B shows the case of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... EGR valve, 2 ... valve box, 2a ... stopper, 3 ... valve passage, 4 ... valve port, 5 ... valve seat, 5a ... valve holder, 6 ...
Valve element, 7: Valve stem, 8: Guide, 9: Spring chamber, 10
... Main valve spring, 11 ... Sub valve spring, 12 ... Spring seat, 12a ... Cotta, 13 ...
Actuator, 14 body, 14a oil seal, 14b wear ring, 15 first port (pressure port), 15a opening, 16 second port (pressure port), 17 suction / discharge port, 18 first Cylinder chamber, 19
… Large diameter chamber, 20… Small diameter chamber, 21… First piston, 22…
Large diameter part, 23 ... Small diameter part, 24 ... Second cylinder chamber, 25 ...
Communication port, 26: stopper, 27: cap, 2
Reference numeral 8 denotes a second piston, 28a an oil seal, 29 a communication passage, 30 a horizontal passage, 30a an introduction passage, 31 a vertical passage, 31a an opening, 32 an upper throttle portion, and 33 a lower throttle portion.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G062 AA01 EA04 GA23 3H052 AA01 BA33 CC03 CD09 EA01 EA16 3H056 AA01 BB49 CA03 CB02 CD04 DD03 DD10 GG03 GG11

Claims (3)

[Claims] A valve opening formed in a valve passage provided in the exhaust gas circulation path; a valve seat formed around the valve opening; A valve body that opens and closes a valve port, a valve stem formed integrally with the valve body, a valve spring that biases the valve stem in a seating direction, and a cylinder chamber formed on an extension of the valve stem, An exhaust gas recirculation valve including a piston slidably fitted into the cylinder chamber and linked to the valve rod, and a pressure port connected to the piston of the cylinder chamber on a side opposite to the valve spring; 3. An exhaust gas recirculation valve according to claim 1, further comprising a throttle means for restricting a flow of fluid in said pressure port near an end point of a return stroke of said piston by said valve spring. 2. The exhaust gas recirculation valve according to claim 1, wherein said throttle means is a throttle portion provided on a surface of said cylinder chamber and said piston facing each other in a sliding direction. 3. A cylinder chamber formed on an extension of the valve stem is formed in a body, wherein the cylinder chamber includes a first cylinder chamber formed inside the body and the first cylinder chamber. And a second cylinder chamber formed inside the first piston, and a second piston is inserted into the second cylinder chamber. The exhaust gas recirculation valve according to claim 1 or 2, wherein: