JPH09158816A - Idle speed control device for internal combustion engine - Google Patents

Abstract

(57) Abstract: In an idle speed control device for an internal combustion engine, manufacturing cost and product variation are suppressed, and responsiveness characteristics to temperature change of engine cooling water are improved. SOLUTION: In a bypass passage 13 connected to an intake passage 12 so as to bypass a throttle valve 11 of an internal combustion engine,
The control valve 14 opened and closed by the step motor 16 and the auxiliary valve 19 opened and closed according to the engine temperature are arranged in series. The auxiliary valve 19 is driven by a bimetal 31 that is displaced by the engine temperature. One end of the bimetal 31 is connected to the auxiliary valve 19, and the other end is fixed to a metal holder 32 having good thermal conductivity by caulking without using an adhesive. The holder 32 is disposed adjacent to the engine temperature detecting unit 17 heated by the engine cooling water, the heat of the engine temperature detecting unit 17 is transferred to the holder 32, and is transferred to the bimetal 31 via the caulking part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device provided in a bypass passage provided in the vicinity of a throttle valve of an intake passage in an internal combustion engine, and more particularly to a bimetal fixing structure for driving an auxiliary valve provided in the bypass passage. Regarding

[0002]

2. Description of the Related Art Conventionally, an internal combustion engine (hereinafter abbreviated as engine)
The idle speed control device of the engine is configured such that a bypass passage provided in the vicinity of the throttle valve is connected to the intake passage so as to bypass the throttle valve, and the idle speed of the engine is controlled to a predetermined value by controlling the amount of air passing through the bypass passage. What is controlled to the target value of is known from Japanese Patent Application Laid-Open No. 7-63143, for example.

In this case, in order to control the amount of air passing through the bypass passage, a control valve and an auxiliary valve are provided in series in the bypass passage, and the amount of bypass air passing through the bypass passage controlled by the control valve is set to the engine temperature. Is regulated by an auxiliary valve that operates in response to.

Since the auxiliary valve is controlled only by the engine temperature, a bimetal which expands and contracts according to changes in the engine temperature is used as its driving means. This bimetal is
It is housed in a bimetal housing chamber in the housing provided on one side of the intake pipe near the throttle valve, and one end of the bimetal is connected to the valve shaft of an auxiliary valve that is openably and closably arranged in a bypass passage formed in the housing. The other end is fitted into the bimetal storage chamber so as to close the open end of the bimetal storage chamber, and is held by a holder to which heat is transferred from the engine. That is, the other end of the bimetal is arranged in a slit formed in the holder, an adhesive is injected around the slit, and the adhesive is fixed to the holder by the adhesive.

When the engine temperature is low (below a predetermined value) when the engine is started, the bimetal is reduced and the auxiliary valve is kept fully open, and the amount of air passing through the bypass passage is controlled only by the control valve. The control valve opening is feedback-controlled based on the engine temperature, engine load variation, etc. to control the engine speed to a substantially target value.

When the engine temperature rises when the engine is warming up, the engine temperature is transmitted to the bimetal through the holder, and the bimetal expands according to the rise of the engine temperature to drive the auxiliary valve in the closing direction. When the engine temperature reaches a predetermined value, the opening degree of the auxiliary valve becomes the minimum, and even if the engine temperature further rises, the auxiliary valve is kept at the minimum opening degree.

[0007]

By the way, conventionally, the bimetal is fixed to the holder by adhering and fixing one end of the bimetal to the bottom of the slit of the holder with an adhesive. However, if an adhesive is used for fixing the bimetal in this way, not only the cost of applying the adhesive and the curing step are required in the manufacturing process, but also the bimetal fixing strength varies depending on the applied state of the adhesive. Occur.

Further, conventionally, the holder is formed with a spiral guide portion matching the winding pitch of the bimetal so that the bimetal can be held in a predetermined state.
The applied adhesive may travel along the interface between one end of the bimetal and the bottom of the slit, reach the effective bending portion and the guide portion of the bimetal, and adhere the effective bending portion to the guide portion. Therefore, there is a problem that the bimetal angle changing characteristic also varies, the temperature characteristic of the bimetal changes from a predetermined characteristic, and the operation characteristic of the auxiliary valve changes.

On the other hand, since an adhesive of epoxy type has been conventionally used and is located at the interface between the holder and the bimetal, heat transfer from the holder to the bimetal is alienated and the temperature of the cooling water of the engine is changed. However, there is a problem that the gonility response of the bimetal is deteriorated.

The present invention has been made in order to solve the above-mentioned problems. By not using an adhesive, the assembling work can be facilitated and the manufacturing cost can be reduced.
It is another object of the present invention to provide an idle speed control device for an internal combustion engine, which can suppress variations in the fixed strength of the bimetal and variations in the gonio characteristics, and can also improve the gonometric response of the bimetal.

[0011]

An idle speed control device for an internal combustion engine according to a first aspect of the present invention is provided with a bypass passage connected to an intake passage so as to bypass a throttle valve of the internal combustion engine, and the bypass passage. A control valve that adjusts the amount of air passing through the bypass passage, a driving unit that drives the control valve, and a control valve that is provided in the bypass passage in series with the control valve and that controls the amount of air passing through the bypass passage together with the control valve. An auxiliary valve for control, a holder having good thermal conductivity which is arranged adjacent to the engine temperature detecting section and transmits the engine temperature, one end of which is connected to the auxiliary valve, and the other end of which is connected to the holder to detect the engine temperature. It is composed of a bimetal that opens and closes the auxiliary valve according to changes, and the other end of the bimetal is fixed to the holder by caulking.

According to a second aspect of the present invention, there is provided an idle speed control device for an internal combustion engine, wherein in the crimp fixing portion between the other end of the bimetal and the holder, the other end of the bimetal is fitted into a slit provided in the holder, The bimetal and the opposing surface of the holder are in close contact with each other.

According to a third aspect of the present invention, in the idle speed control device for an internal combustion engine, when the other end of the bimetal is fixed to the holder by crimping, a clearance is provided between the effective bending portion of the bimetal and the holder. Configured to be formed.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 1 to 3 show an embodiment of an idle speed control device according to the present invention. FIG. 1 is a sectional view of a main part thereof, FIG. 2 is a sectional view taken along line II-II thereof, and FIG. 4 side view of the device of FIG.
4 is a sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is an enlarged view of a portion A in FIG.

In FIG. 1, reference numeral 15 is a throttle body inserted in the middle of an intake pipe (not shown) of the internal combustion engine,
The intake passage 12 formed in the throttle body 15
Is provided with a throttle valve 11 for adjusting the amount of air passing therethrough, and the throttle valve 11 is attached to a rotary shaft 10 rotatably supported by a throttle body 15. At one side of the throttle body 15, an inlet passage 13a and an outlet passage 13e branched from the intake passage 12 are provided.
Is formed, and the idle rotation control device body 17 is formed.
(Hereinafter, abbreviated as a device body) is attached.

The device body 17 includes a throttle body 15
A substantially U-shaped passage communicating with the inlet passage 13a and the outlet passage 13e is formed, and the inlet passage 13a, the U-shaped passage, and the outlet passage 13e form a bypass passage 13 that bypasses the throttle valve 11. The U-shaped passage formed in the apparatus body 17 includes a first passage 13b communicating with the inlet passage 13a, an intermediate second passage 13c, and an outlet passage 13e.
A third passage 13d that communicates with each other, and these first to third passages 13b-13d communicate with each other. The air flow path to the engine in the bypass passage 13 is as shown by the arrow in FIG.

The first passage 13b and the second passage in the apparatus body 17
A control valve 14 is arranged at the connecting portion of the passage 13c, and the control valve 14 is driven by a step motor 16 attached to the apparatus main body 17 to form an annular opening 18 formed upstream of the second passage 13c. It reciprocates oppositely to change the flow passage area.

Further, an auxiliary valve 19 is provided in the second passage 13c, and the auxiliary valve 19 is driven by a temperature detecting mechanism 34 provided in the second passage 13c to rotate to bypass the bypass passage 13. Open and close. The details of the temperature detection mechanism 34 will be described later.

A cooling water passage 25 through which engine cooling water is introduced is formed in the apparatus body 17 and the throttle body 15, and the cooling water flows in from an inlet portion 25a formed on the temperature detecting mechanism 34 side of the apparatus body 17. Bypass passage 13
Outlet 25b formed on the opposite side of the inlet 25a across the
Spill out of. In this way, the apparatus body 17 is heated to a temperature substantially equal to the engine temperature by the engine cooling water flowing through the cooling water passage 25, and constitutes an engine temperature detecting portion.

The constructions of the auxiliary valve 19 and the temperature detecting mechanism 34 will be described with reference to FIG.

The auxiliary valve 19 comprises a thin elliptical valve body (butterfly valve) 20, shaft portions 21 and 22 projecting from both ends of the valve body 20, and a guide portion 23. The valve body 20 and the shaft portions 21 and 22 are integrally molded of synthetic resin. A protrusion 24 is formed on the outer peripheral surface of the guide portion 23, and the protrusion 24 is configured to be engageable with a stopper (not shown) provided in the apparatus body 17. Therefore, the auxiliary valve 19 is rotatable within the range in which the protrusion 24 is engaged with the stopper. The auxiliary valve 19
Even when the passage 13c is closed, a predetermined clearance is formed between the valve body 20 and the inner wall surface of the second passage 13c, and a predetermined flow passage area is secured.

One shaft portion 21 is inserted into a recess 26 provided in the apparatus body 17, and the other shaft portion 22 is provided in the apparatus body 17.
It is fitted in a bearing 28 provided in the bearing hole 27 of the. Therefore, in the opening / closing operation of the valve body 20, the shaft portion 21,
22 slides relative to the recess 26 and the bearing 28, respectively.

The bearing 28 is an annular member formed of synthetic resin, and is divided by a plane including the shaft center and is composed of two half bearings.

The guide portion 23 has a bimetal 31 which will be described later.
It has a slit 29 extending in the axial direction for inserting the one end 31a of the first end 31a, and is accommodated in a bimetal accommodation chamber 30 formed in the apparatus main body 17. A coil-shaped bimetal 31 is housed in the bimetal storage chamber 30, and an appropriate clearance is provided between the inner wall of the bimetal storage chamber 30 and the outer periphery of the bimetal 31 so as not to interfere with the rotation of the bimetal 31. Is provided. The bimetal accommodating chamber 30 is closed by a holder 32 made of a material having good thermal conductivity such as aluminum alloy, and the flange 35 of the holder 32 abuts on the outer wall surface of the apparatus main body 17.
In the slot 36 (see FIG. 3) formed in the holder 5, the holder 32
A screw 37 for fixing the
The holder 32 is fixed to the apparatus main body 17 by tightening the screw 37.

As shown in detail in FIGS. 3 and 4, the holder 32 has a slit 33 into which the other end 31b of the bimetal 31 is inserted, like the guide portion 23. A flat portion 32a having a step-like shape is provided for fixing the other end 31b of the stake by crimping. One end 31a of the bimetal 31 is inserted into the slit 29 of the guide portion 23, the other end 31b is inserted into the slit 33 of the holder 32, and the flat surface portion 32a of the holder 32 is attached to both side surfaces of the other end 31b of the bimetal 31 (see FIG. Middle upper and lower side)
By caulking, the other end 31b of the bimetal 31
Are fixed to the holder 32.

Here, the opposing surfaces of the one end 31a of the bimetal 31 and the bottom portion 32b of the slit 33 are in close contact with each other, and the effective angle changing portion 31c of the bimetal 31 and the spiral guide portion 32c of the holder 32 are suitable. Clearance δ
The shape of the holder 32 is set so as to have. In this way, the bimetal 31, the holder 32, and the guide portion 23 constitute the temperature detection mechanism 34.

The cooling water passage 25 is formed in the apparatus main body 17 in the vicinity of the temperature detecting mechanism 34. Therefore, the heat of the cooling water of the engine flowing in the cooling water passage 25 is passed from the apparatus main body 17 through the holder 32. It is transmitted to the bimetal 31. That is, the bimetal 31 deforms according to the temperature of the engine, and the other end 31b of the bimetal 31 rotates.
As a result, the guide portion 23 and the valve body 20 are rotationally displaced,
The flow passage area of the bypass passage 13 is controlled.

According to this structure, the bimetal 31 is held in the holder 32 without using an adhesive as in the conventional case.
Since it can be fixed to the adhesive, it is possible to reduce the steps of application and curing treatment when using an adhesive, and the effective bending portion 31c of the bimetal 31 and the spiral guide portion 32c of the holder 32 due to the outflow of the adhesive. No worries about sticking. If the caulking force and the caulking depth are controlled when the one end 31b of the bimetal 31 is caulked, the variation in the fixing strength of the bimetal 31 can be suppressed more easily than the fixing by the adhesive.

Further, since the other end 31b of the bimetal 31 and the facing surface of the slit bottom portion 32b of the holder 32 are in close contact with each other, heat transfer from the holder 32 to the bimetal 31 is improved, and the bimetal against the temperature change of the engine cooling water. Bending responsiveness of is improved.

The effective angle changing portion 31 of the bimetal 31
Since the c and the spiral guide portion 32c of the holder 32 have an appropriate clearance, there is no friction loss due to contact with the spiral guide portion 32c when the bimetal 31 makes a rotational movement, and the bimetal 31 has a variable angle. The variation in characteristics can be further suppressed.

Next, the operation will be described. The opening degree of the control valve 14 is controlled by a computer (not shown) via the step motor 16, and changes according to the temperature of the engine cooling water and the load variation of the engine (ON / OFF of the air conditioner switch, operating state of the power steering, etc.). The opening degree of the auxiliary valve 19 is controlled by the temperature detection mechanism 34 and changes only by the temperature of the engine cooling water. When cold, both the control valve 14 and the auxiliary valve 19 are fully open. As the engine temperature rises after the engine is started (when the engine temperature exceeds the first predetermined value), the opening degrees of these valves 14 and 19 both decrease. After the warm-up is completed (after the engine temperature reaches the second predetermined value), the auxiliary valve 19 is fixed to a predetermined opening by a stopper, but the control valve 14 sets the engine speed to a predetermined value. Feedback controlled.

FIG. 5 shows the relationship between the opening degrees of the control valve 14 and the auxiliary valve 19 and the air flow rate Q passing through the bypass passage 13. When the opening of the control valve 14 is relatively small, the solid line R
As shown by, the air amount Q is substantially determined only by the opening degree of the control valve 14, and the opening degree of the auxiliary valve 19 does not affect the control of the air amount Q. When the opening degree of the control valve 14 further increases, the effect of the auxiliary valve 19 appears, as indicated by the symbol S, and the air amount Q depends on the opening degrees of both the control valve 14 and the auxiliary valve 19.

Bimetal 3 as the temperature of the cooling water rises
Since the opening degree of the auxiliary valve 19 is reduced by the operation of 1, the air amount Q decreases as the temperature of the cooling water rises, as indicated by the symbol T, for example, when the control valve 14 is fully open. The temperature of the cooling water is a predetermined value (40 ° in the illustrated example).
Ascending to C), the auxiliary valve 19 is closed, after which the air quantity Q becomes substantially controlled by the control valve 14 only, as indicated by the symbol U. When the temperature of the cooling water is lower than the predetermined value, the auxiliary valve 19 operates, so that the air amount Q can be controlled by the control region indicated by the symbol W.

It should be noted that the opening amounts of the control valve 14 and the auxiliary valve 19 in the fully opened state are such that even if both of the control valve 14 and the auxiliary valve 19 are locked in the fully opened state, the air amount Q supplied to the engine is indicated by a solid line. As indicated by V, the value is suppressed to a predetermined value, and the idle speed is controlled so as to be higher than the normal value by at most 2500 rpm.

As described above, according to the present invention, since the bimetal is fixed to the holder by crimping without using the adhesive, the application of the adhesive can be performed as compared with the conventional case where the adhesive is used. It is possible to reduce the number of curing processes and curing processes, suppress variations in manufacturing cost and product quality, and improve the response characteristics of the idle speed control device to changes in engine temperature.

Further, in the caulking fixing portion between the other end of the bimetal and the holder, the other end of the bimetal is fitted into the slit provided in the holder so that the opposing surfaces of the bimetal and the holder are in close contact with each other. The heat transferred from the engine temperature detection unit to the holder is efficiently transferred from the holder to the bimetal through the closely contacted opposing surfaces, and therefore the responsiveness to changes in the engine temperature is further improved.

Further, when the other end of the bimetal is caulked and fixed to the holder, a clearance is formed between the effective angle changing portion of the bimetal and the holder. Since there is no friction loss due to abutting, the variation of the bimetal bending characteristic can be further suppressed.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of an idle speed control device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II.

FIG. 3 is a side view seen from the right direction in FIG.

4 is a sectional view taken along line IV-IV of FIG.

FIG. 5 is an enlarged view of a portion A in FIG. 4;

FIG. 6 is a diagram showing a relationship between changes in the opening amounts of the control valve and the auxiliary valve and changes in the air amount in the bypass passage.

[Explanation of symbols]

11 throttle valve, 12 intake passage, 13 bypass passage, 14 control valve, 16 step motor as driving means, 17 idle speed control device body as engine temperature detector, 19 auxiliary valve, 31 bimetal,
32 holders, 33 slits.

Claims (3)

[Claims] 1. A bypass passage connected to an intake passage so as to bypass a throttle valve of an internal combustion engine, a control valve provided in the bypass passage for adjusting the amount of air passing through the bypass passage, and a drive valve for driving the control valve. Driving means, an auxiliary valve provided in the bypass passage in series with the control valve, for controlling the amount of air passing through the bypass passage together with the control valve, and arranged adjacent to the engine temperature detection unit to transmit the engine temperature. And a bimetal having one end connected to the auxiliary valve and the other end connected to the holder to open and close the auxiliary valve according to a change in engine temperature. An idle speed control device for an internal combustion engine, wherein the other end is fixed to the holder by crimping. 2. In the crimp fixing portion between the other end of the bimetal and the holder, the other end of the bimetal is fitted into a slit provided in the holder, and the opposing surfaces of the bimetal and the holder are in close contact with each other. The idle speed control device for an internal combustion engine according to claim 1, wherein 3. A clearance is formed between the effective bending portion of the bimetal and the holder when the other end of the bimetal is fixed to the holder by crimping. Item 3. An idle speed control device for an internal combustion engine according to item 2.