JP3124406B2 - Intake flow control valve for warm-up operation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air flow control valve disposed in a passage that bypasses a throttle valve in a main intake passage to warm up an engine by increasing the idling speed when the engine is cold. It is.

[0002]

2. Description of the Related Art During the warm-up operation of an engine, even if the throttle valve is closed in an idling state, it is necessary to increase the idling speed by increasing the intake air amount, for example, by increasing the actual opening rate 1-1.
As disclosed in Japanese Patent No. 73434, a passage bypassing a throttle valve and an intake flow control valve for warm-up operation for opening / closing the passage are provided. The intake flow control valve is shown in FIG.
As shown in the figure, the main intake passage 22 of the throttle body 21
24a communicating with the upstream side of the throttle valve 23 disposed at
And a space 24b communicating with the downstream side, a valve seat 25 is provided, and a valve body 28 that opens and closes a valve port is provided at a tip end of a driven member 27 that is moved toward the valve seat 25 by a thermally responsive actuator 26. Is provided. The valve element 28 is engaged with the distal end flange 29 so as not to come off from the distal end of the driven member 27, and is urged by the pressing spring 30 to
The valve spring 31 is removably held at the distal end of the valve spring 31.
Is always urged toward the operating shaft 32 of the thermally responsive actuator 26. Then, the thermally responsive actuator 26
A cooling water passage 33 for circulating the cooling water of the engine is provided in the heat sensing portion 26a.

[0003] With the above configuration, when the engine is cold, the operating shaft 32 of the thermally responsive actuator 26 is retracted by the urging force of the valve spring 31, and from the upstream side of the throttle valve 23 to the space 24.
a, the intake air is bypass-supplied to the downstream side of the throttle valve 23 through a passage between the valve seat 25 and the valve body 28 and the space 24b,
The idling speed increases and the engine enters a warm-up operation state.

Thereafter, when the engine temperature rises, the operating shaft 32 of the thermally responsive actuator 26 protrudes against the urging force of the valve spring 31, and the valve body 28 moves toward the valve seat 25 via the driven member 27. The valve opening closes and the engine enters a normal idling state. When the engine temperature further rises and the operating shaft 32 of the thermally responsive actuator 26 further projects, the valve body 28 retreats against the urging force of the pressing spring 30, so that
It will not be damaged by excessive force.

As shown in FIG. 6, a valve seat 43 is screwed and fixed to the inner periphery of a case 42 as an intake flow control valve 41 for warming-up operation, and spaces 44a and 44b on both sides thereof are formed in a main intake passage ( (Not shown) communicates with the upstream portion and the downstream portion of the throttle valve through communication passages (not shown), respectively, to form a bypass passage of the throttle valve in the main intake passage, and an operating shaft 47 of the thermally responsive actuator 46. There is also known a device provided with a valve body 45 that moves between a state where the valve is closed by the movement of the valve and a state where the spaces 44a and 44b communicate with each other. In the example of FIG. 6, a tubular portion 48a provided at the base of a driven member 48 is slidably fitted on a tubular shaft portion 46b protruding toward the valve seat 43 side of the thermally responsive actuator 46. The operating shaft 47 is brought into contact with the bottom surface 48b, the receiving member 49 is engaged with a step formed on the outer periphery of the cylindrical portion 48a, and the driven member 48 is interposed between the receiving member 49 and the valve seat 43 via the driven member 48. A valve spring 50 for separating the valve body 45 from the valve seat 43 is interposed, and a driven member 48 is provided.
The valve body 45 is slidably fitted to the shaft portion 48c on the distal end side of the shaft member 48, the end plate 51 for preventing the valve body 45 from coming off is fixed to the distal end of the shaft portion 48c, and the seat member 49 and the valve body 4 are fixed.
A pressure spring 52 is interposed between the valve body 5 and the valve body 5 to constantly bias the valve body 45 toward the end plate 51.

The characteristic of the intake flow control valve 41 is that the bypass passage is gradually closed as the water temperature rises, and between the end plate 51 at the tip of the shaft portion 48c and the tip of the valve body 45 after the valve is closed. The gap is opened in the shaft hole 45 of the valve body 45.
The point is that intake air for idling flows through a gap between the shaft member 48a and the shaft portion 48c of the driven member 48.

[0007]

By the way, in the configuration of the intake air flow control valve for warm-up operation shown in FIG. 5, the engine is warmed up and the main valve is closed immediately before the valve port of the valve seat 25 is closed by the valve body 28. Due to the pressure difference between the upstream side and the downstream side of the throttle valve 23 in the intake passage 22, the valve body 28 is rapidly closed against the valve spring 31 and a sharp drop occurs in the intake air flow rate, thereby causing the engine speed to decrease. There is a problem that the engine stall may be caused.

Further, in the configuration of the intake air flow control valve for warming-up operation shown in FIG.
7, the intake air flow rate does not decrease smoothly as shown by the imaginary line in FIG. 7, and not only does the intake air flow rate drop sharply, but also the tip end face of the valve body 45 and the end plate 51 Due to the close contact, the shaft hole 45a of the valve body 45 and the driven member 4
As shown by the solid line in FIG. 7, the intake air flow for idling supplied through the gap between the shaft portions 48c of FIG. Further, this state continues until the cooling water temperature further rises, the operating shaft 47 of the thermally responsive actuator 46 projects, and the end plate 51 at the tip of the driven member 48 separates from the tip face of the valve body 45. During the temperature range A shown in FIG. 7, there is a problem that the intake air flow rate is significantly reduced, and as a result, engine stall may occur.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a warm-up operation intake flow control valve which can eliminate a sudden decrease in flow immediately before valve closing and does not cause engine stall. And

[0010]

The intake air flow control valve for warm-up operation of the present invention is disposed in a passage that bypasses a throttle valve provided in a main intake passage, and is controlled to be opened and closed by a thermally responsive actuator. In the machine-operated intake flow control valve, the operating shaft of the thermally responsive actuator is brought into contact with the base of a driven member that is movable in the axial direction of the valve seat and has a valve body disposed at the tip, and the driven member is A valve spring biasing in a direction away from the valve seat is provided, and the valve body is slidably fitted to the distal end shaft portion of the driven member, and is brought into contact with an end plate fixed to the distal end of the driven member by a pressing spring. In addition, a ventilation groove communicating with the outer periphery from the shaft hole of the valve body is formed on a contact surface of the valve body with the end plate.

[0011]

According to the present invention, even if the force for pressing the valve body toward the valve seat against the valve spring acts due to the pressure difference between the upstream side and the downstream side of the throttle valve immediately before closing the valve. Since the valve body is slidably fitted to the distal end shaft portion of the driven member, the intake air passes through the gap between the shaft hole of the valve body and the distal end shaft portion, and further comes into contact with the valve body and the end plate. Flow through the ventilation groove formed on the surface prevents the valve from closing suddenly, and also prevents a sudden decrease in the flow rate of intake air when the valve closes, preventing a drop in idling speed. Then, the fear of stalling can be eliminated.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An intake air flow control valve for warm-up operation according to an embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is an intake flow control valve, 2 is a case thereof, and 3 is a valve seat screwed and fixed to an inner periphery thereof. Reference numerals 4a and 4b denote spaces on both sides of the valve seat 3, which are respectively communicated with upstream and downstream portions of a throttle valve in a main intake passage (not shown) via communication passages (not shown) as appropriate. The throttle valve constitutes a bypass passage.

Reference numeral 5 denotes a valve body, which is in a state where the valve is brought into contact with the valve seat 3 and closed by the movement of the operating shaft 7 of the thermally responsive actuator 6 and a state where the spaces 4a and 4b are separated from the valve seat 3 and communicate with each other. Moved between.

A cylindrical portion 8a provided at the base of a driven member 8 is slidably fitted to the outside of a tubular shaft portion 6b projecting from the main body 6a of the thermally responsive actuator 6 toward the valve seat 3. The operating shaft 7 is in contact with the bottom surface 8b. A receiving member 9 is engaged with a step formed on the outer periphery of the cylindrical portion 8a, and the valve 5 separates the valve body 5 from the valve seat 3 via the driven member 8 between the receiving member 9 and the valve seat 3. A spring 10 is interposed. The valve element 5 is slidably fitted to the shaft portion 8c on the distal end side of the driven member 8. End plate 1 for preventing the valve body 5 from coming off
1 is fixed to the tip of the shaft portion 8c, and a pressing spring 12 is interposed between the seat member 9 and the valve body 5, and the valve body 5 is constantly biased toward the end plate 11.

As shown in detail in FIG. 2, a ventilation groove 13 communicating from the shaft hole 5a of the valve element 5 to the outer periphery is formed radially on the contact surface of the tip of the valve element 5 with the end plate 11. Have been.

In FIG. 1, reference numeral 6c denotes a heat-sensitive portion of the thermally responsive actuator 6, which is configured so that cooling water for an engine (not shown) is circulated and supplied therearound.

In the above configuration, when the engine is cold, since the cooling water flows through the heat-sensitive portion 6c of the thermally responsive actuator 6, the operating shaft 7 of the thermally responsive actuator 6 retreats as shown in FIG. The valve element 5 is separated from the valve seat 3 via the driven member 8 urged by the valve spring 10, and the spaces 4a and 4b on both sides communicate with each other to bypass a throttle valve (not shown) in the main intake passage. The passage is open.
Therefore, intake air flows through the bypass passage from the upstream portion to the downstream portion of the throttle valve in the main intake passage, the idling speed increases, and the warm-up operation is performed.

When the temperature of the engine coolant rises,
The operating shaft 7 of the thermally responsive actuator 6 gradually projects, the driven member 8 moves toward the valve seat 3 against the urging force of the valve spring 10, the valve body 5 approaches the valve seat 3, and the bypass passage is gradually formed. As shown in FIG. 4, the flow rate of intake air passing through the bypass passage decreases as the coolant temperature rises, and the idling speed decreases.

When the temperature of the cooling water rises to about 70 ° C., the operating shaft 7 of the thermally responsive actuator 6 projects until the valve element 5 approaches the valve seat 3 as shown in FIG.
In this state, the valve body 5 is pressed toward the valve seat 3 by the pressure difference between the upstream side and the downstream side of the throttle valve in the main intake passage, and the valve is rapidly closed against the urging force of the valve spring 10. Force acts. Therefore, the ventilation groove 1 is provided at the tip of the valve body 5.
3 is not formed, even if a gap exists between the shaft hole 5a of the valve body 5 and the shaft portion 8b of the driven member 8,
4, the intake air supplied through the bypass passage is sharply reduced, as shown by a broken line in FIG. 4, which may cause engine stall. This state continues until the temperature of the cooling water further rises, the operating shaft 7 of the thermally responsive actuator 6 projects, and the end plate 11 at the tip of the driven member 8 separates from the tip end surface of the valve element 5. However, in this embodiment, since the ventilation groove 13 is provided on the distal end surface of the valve element 5, the shaft hole 5 of the valve element 5 is removed from the space 4a.
a between the shaft portion 8a of the driven member 8 and the ventilation groove 13
An intake passage is formed to reach the space 4b through the valve body 5. As a result, the valve body 5 can be prevented from being rapidly closed, and even if the valve body 5 is closed, the axial hole of the valve body 5 extends from the space 4a. Since a certain amount of intake air flows into the space 4b through the gap between the shaft member 5a and the shaft portion 8b of the driven member 8 and the ventilation groove 13, as shown by the solid line in FIG. At the end of the warm-up operation, the intake air amount is sharply reduced, so that there is no danger that the idling speed decreases or engine stall occurs.

Thereafter, when the temperature of the cooling water further rises and enters a steady operation state of, for example, about 80 ° C., the amount of protrusion of the operating shaft 7 of the thermally responsive actuator 6 increases, and FIG.
As shown in (b), the driven member 8 moves toward the valve seat 3 against the urging force of the valve spring and the pressing spring, and the end plate 11 at the tip of the driven member 8 is separated from the tip surface of the valve element 5. I do. In this state, the idle ring operation is performed by the intake air passing through the gap between the shaft hole of the valve element 5 and the distal end shaft portion 8b of the driven member 8. The intake air amount is, for example, about 1 m ³ / H.

[0022]

According to the intake air flow control valve for warm-up operation of the present invention, the force for pushing the valve body toward the valve seat by the pressure difference between the upstream side and the downstream side of the throttle valve immediately before closing the valve acts. Even
Since the valve body is slidably fitted to the distal end shaft portion of the driven member, and further, a ventilation groove is formed on the contact surface between the valve body and the end plate,
The intake air flows through the gap between the shaft hole of the valve body and the tip shaft portion and the ventilation groove, so that the valve can be prevented from suddenly closing, and the rapid flow rate of the intake air when the valve closes The decrease can be suppressed, the decrease in the idling rotational speed can be prevented, and the possibility of engine stall can be eliminated.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional front view of a warm-up intake air flow control valve according to an embodiment of the present invention.

FIGS. 2A and 2B are enlarged views of a valve body and a leading end of a driven member in the embodiment, wherein FIG. 2A is a side view and FIG.

3A and 3B show an operation state of the embodiment, in which FIG. 3A is a cross-sectional view in a temperature state in which a valve body contacts a valve seat, and FIG. 3B is a cross-sectional view in a higher temperature state.

FIG. 4 is a characteristic diagram of a cooling water temperature of an engine and an intake air amount flowing through an intake air flow control valve.

FIG. 5 is a sectional front view of a conventional intake air flow control valve for warming-up.

FIG. 6 is a cross-sectional front view of a main portion of another conventional intake air flow control valve for warm-up.

FIG. 7 is a characteristic diagram of a cooling water temperature and an intake air flow rate showing a problem of the warm-up intake air flow control valve of FIG. 6;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 intake air flow control valve 3 valve seat 5 valve body 6 thermally responsive actuator 7 operating shaft 8 driven member 10 valve spring 11 end plate 12 pressing spring 13 ventilation groove

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-323222 (JP, A) JP-A-3-229080 (JP, A) JP-A-64-12041 (JP, A) 173434 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 33/00

Claims (1)

(57) [Claims] An intake air flow control valve for warm-up operation, which is disposed in a passage that bypasses a throttle valve provided in a main intake passage and that is opened and closed by a thermally responsive actuator, moves in an axial direction of a valve seat. A valve spring that freely and abuts the operating shaft of the thermally responsive actuator against the base of the driven member having the valve element disposed at the distal end thereof, and biases the driven member in a direction away from the valve seat; Is slidably fitted to the distal end shaft portion of the driven member, is brought into contact with an end plate fixed to the distal end of the driven member by a pressing spring, and the valve body is brought into contact with the end plate of the valve body. An intake flow control valve for warm-up operation, wherein a ventilation groove communicating from a shaft hole to an outer periphery is formed.