JPH0324848Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention relates to a fast idle device for a carburetor installed in the intake pipe of an on-vehicle engine. This invention relates to an improvement in a fast idle device for a carburetor that opens and closes a throttle valve via an operating lever mounted around a throttle shaft using a cam surface.

(Prior Art) Conventionally, there is a type of throttle lever that opens and closes using a cam that is interlocked with a temperature-responsive member, such as that described in Japanese Utility Model Application No. 55-28856. .

Conventionally, as shown in FIG. 4, an operating lever 6' is attached around the throttle shaft 3 of a throttle valve 4 which is disposed in the intake passage 2 of the carburetor body 1 so as to be openable and closable.
is attached, and an interlocking cam 12' having a cam surface 18' that is in constant contact with the engagement pin 17' of the operating lever 6' is attached to the temperature-responsive member 10 at a predetermined position on the carburetor body 1.
Some devices are arranged to be operated by.

(Problems to be Solved by the Invention) In the above-mentioned conventional system, the cam surface 18' of the interlocking cam 12' comes into contact with the engagement pin 17' of the operating lever 6', with emphasis placed on the startability of the engine. If , that is, if the opening degree of the throttle valve 4 is set to a large value, the idling speed of the engine will become higher than necessary during warm-up operation after starting the engine. Therefore, during warm-up operation, problems arise such as deterioration of fuel efficiency and deterioration of engine braking effectiveness.

On the other hand, if the opening degree of the throttle valve 4 is set to a small value, a problem arises in that the startability of the engine deteriorates.

(Means for Solving the Problems) In order to solve the above-mentioned conventional problems, in this invention, an operating lever attached around the throttle axis engages an interlocking cam that is interlocked by a temperature-responsive member. A starting cam surface and a warming-up cam surface are respectively formed to selectively engage with the mating pin, and at a predetermined position on the carburetor body, the engaging pin of the operating lever engages with the starting cam surface when the engine is started. A diaphragm device is provided with an actuating rod that holds the actuating lever in abutting position and retracts when the engine negative pressure reaches a predetermined value or more, and further, the actuating rod retracts and the throttle valve When the operating lever is rotated in the direction of closing the valve by the biasing force of the return spring, the engagement pin of the lever comes into contact with the warm-up cam surface.

(Function) Therefore, in this invention, when the engine is started, the operating rod of the diaphragm device holds the operating lever at a position where the engaging pin of the operating lever comes into contact with the starting cam surface. The throttle valve is opened at the appropriate opening.

In addition, during warm-up operation when the engine negative pressure reaches a predetermined value or more after the engine is started, the operating rod of the diaphragm device is moved backward, and the operating lever is rotated in the direction of closing the throttle valve. When the engagement pin contacts the warm-up cam surface, the throttle valve is closed to an opening suitable for engine warm-up.

(Example) An example of this invention will be described below with reference to FIGS. 1 to 3.

In FIG. 1, which shows a front view of the fast idle device of a carburetor installed in the intake pipe of an in-vehicle engine, a throttle valve 4 is located within the intake passage 2 of the carburetor body 1 and can be opened and closed around a throttle shaft 3. It is located in

The shaft end of the throttle shaft 3 protrudes from the outer surface of the carburetor body 1 by a predetermined length, and a throttle arm 5 and an operating lever (fast idle lever) 6 are respectively attached around the shaft. .

The throttle arm 5 is integrally fixed to the throttle shaft 3, and the arm 5 and the carburetor main body 1
A return spring 7 is tensioned between the throttle valve 4 and the throttle valve 4 to constantly bias the throttle valve 4 in the closing direction.

The operating lever 6 is fitted to be rotatable around the throttle shaft 3, and one end of the operating lever 6 is fitted with the tip of an idle adjustment bolt 8 that is screwed into the throttle arm 5 so that it can move forward and backward. A contact surface 6a is formed with which the surface is always in contact. A spring 9 for preventing loosening is interposed around the axis of the idle adjustment bolt 8 between its head and the throttle arm 5.

A well-known temperature-responsive member 10 of the ThermoWorks type that utilizes the thermal expansion of wax is disposed at a predetermined position of the vaporizer body 1. This temperature responsive member 10
The temperature-responsive shaft 11 protrudes when the ambient temperature rises due to heat or electric heat of exhaust gas or engine cooling water after starting the engine, and retreats when the ambient temperature drops to a low level.

The carburetor main body 1 has a position operated by the temperature-responsive shaft 11 of the temperature-responsive member 10.
An interlocking cam 12 is rotatably mounted around a support shaft 13. An adjustment bolt 14 is attached to a support piece 12a formed at a predetermined position of this interlocking cam 12.
are screwed together so that they can move forward and backward, and are prevented from turning by a lock nut 15. The tip end surface of the adjustment bolt 14 is connected to the temperature responsive shaft 1 of the temperature responsive member 10.
1, the interlocking cam 12 is urged counterclockwise in FIG. There is. When the ambient temperature is low and the temperature-responsive shaft 11 of the temperature-responsive member 10 is retracted, the interlocking cam 12 is rotated counterclockwise in FIG. 1 by the biasing force of the spring 16. In addition, when the ambient temperature is high, the temperature-responsive shaft 1 of the temperature-responsive member 10
1 is advanced, the motion cam 12
It is rotated clockwise in FIG. 1 against the biasing force 6.

An operating lever 6 is provided at the tip of the interlocking cam 12.
A long groove into which an engaging pin 17 protrudingly provided at the tip is inserted is formed, and a starting cam surface 18 that selectively engages with the engaging pin 17 of the operating lever 6 is formed on both sides of this long groove. and a warm-up cam surface 19 are respectively formed.

A diaphragm device 20 is disposed in the carburetor main body 1 at a position facing the operating lever 6. The proximal end of an actuating rod 22 is fixed to the membrane 21 of the diaphragm device 20, and the distal end surface of the actuating rod 22 faces a rod contact surface 6b formed at a predetermined position of the actuating lever 6 so as to be able to approach and separate from it. are doing. Further, a negative pressure chamber 23 defined within the diaphragm device 20 is connected to the intake pipe of the engine, and an actuating rod 22 is provided within the negative pressure chamber 23.
A spring 24 is interposed to push the rod toward the rod abutment surface 6b of the actuating lever 6. This extrusion spring 2
The spring force of 4 is the return spring 7 of the throttle valve 4.
The spring force is set appropriately larger than the spring force. When the negative pressure in the negative pressure chamber 23 is below a predetermined value, such as when starting the engine, the tip end surface of the actuating rod 22 is pushed out by the urging force of the pushing spring 24, as shown in FIG. is in pressure contact with the rod contact surface 6b of the actuating lever 6, and the engagement pin 1 of the actuating lever 6
7 holds the actuating lever 6 at a position where it comes into contact with the starting cam surface 18.

When the negative pressure in the negative pressure chamber 23 exceeds a predetermined value, such as during warm-up operation after starting the engine, the second
As shown in the figure, the actuating rod 22 is retracted by the negative pressure action. At this time, the operating lever 6 is rotated in the closing direction of the throttle valve 4 via the throttle arm 5 and the idle adjustment bolt 8 by the urging force of the return spring 7, and the engaging pin 17 of the operating lever 6 is rotated. is configured to abut against the warm-up cam surface 19.

Furthermore, the starting cam surface 18 of the interlocking cam 12 that is interlocked by the temperature responsive member 10 is set so as to obtain an opening degree of the throttle valve 4 suitable for starting the engine in accordance with the ambient temperature. . Further, the warm-up cam surface 19 of the interlocking cam 12 is set so as to obtain an opening degree of the throttle valve 4 suitable for the warm-up operation after starting the engine and the ambient temperature.

This embodiment is constructed as described above, and therefore, when the engine is started (just before and after starting), the temperature-responsive shaft 11 of the temperature-responsive member 10 moves back and forth in accordance with the ambient temperature. The actuating lever 6 is connected to the actuating rod 2 of the diaphragm device 20 at a position where the engaging pin 17 of the actuating lever 6 contacts the starting cam surface 18 of the interlocking cam 12 that is interlocked with the actuating lever 6.
2. The operating lever 6 then controls the throttle valve 4 via the idle adjustment bolt 8 and the throttle arm 5 to an opening that corresponds to the ambient temperature and is suitable for starting the engine (as shown by the solid line in Figure 3). (see characteristic line). Therefore, the engine starts smoothly.

After starting the engine, during warm-up operation when the engine negative pressure reaches a predetermined value or higher, the actuating rod 22 of the diaphragm device 20 is retracted, as shown in FIG. Then, the operating lever 6 is rotated in the direction of closing the throttle valve 4 by the biasing force of the return spring 7, and the engagement pin 17 of the operating lever 6 comes into contact with the warm-up cam surface 19. Then, the floattle valve 4 is closed to an opening degree suitable for warming up the engine.

When the ambient temperature gradually increases during engine warm-up, the temperature-responsive shaft 11 of the temperature-responsive member 10 is also sequentially advanced. Along with this, the interlocking cam 12 is rotated clockwise in FIG. 2 against the biasing force of the spring 16. Then, the operating lever 6 is rotated in the closing direction of the throttle valve 4 by the biasing force of the return spring 7, and the interlocking cam 12 is rotated.
Since the contact position of the engaging pin 17 of the actuating lever 6 against the warm-up cam surface 19 of (see line) becomes smaller successively. Therefore, the idle speed of the engine during warm-up operation is prevented from becoming higher than necessary, and is always maintained at an appropriate speed.

In addition, in the above embodiment, the diaphragm device 20
The negative pressure chamber 23 of the engine is connected directly to the intake pipe of the engine, but by interposing a delay device, a timer, etc. between the negative pressure chamber 23 and the intake pipe, the time of negative pressure generation in the engine can be adjusted as appropriate. The negative pressure chamber 23 may be brought into negative pressure with a delay.

(Effects of the invention) As described above, according to this invention, when the engine is started, the actuation rod of the diaphragm device holds the actuation lever at a position where the engagement pin of the actuation lever comes into contact with the starting cam surface. This allows the throttle valve to be opened to an opening degree suitable for starting the engine.

In addition, during warm-up operation when the engine negative pressure reaches a predetermined value or more after the engine is started, the operating rod of the diaphragm device is moved backward, and the operating lever is accordingly rotated in the direction of closing the throttle valve.
By bringing the engagement pin of the lever into contact with the warming-up cam surface, the throttle valve can be closed to an opening degree suitable for warming up the engine.

Therefore, it is possible to improve the startability of the engine, and on the other hand, it is possible to prevent deterioration in fuel consumption during warm-up operation of the engine and deterioration in the effectiveness of the engine brake.

[Brief explanation of the drawing]

Figures 1 to 3 of the drawings show an embodiment of this invention, with Figure 1 being a front view showing the fast idle device during engine startup, and Figure 2 showing the fast idle device during warm-up operation. The front view and FIG. 3 are characteristic diagrams showing the opening degree of the throttle valve at the time of starting the engine and during warm-up operation. FIG. 4 is a front view showing the conventional one. 1... Carburetor body, 3... Throttle shaft, 4...
... Throttle valve, 6... Actuation lever, 7...
Return spring, 10... Temperature responsive member, 12... Interlocking cam, 17... Engagement pin, 18... Cam surface for starting, 19... Cam surface for warming up, 20... Diaphragm device, 22... Operation Rod.

Claims (1)

[Scope of utility model registration request] A fast idle device for a carburetor that opens and closes a throttle valve via an operating lever mounted around a throttle shaft by a cam surface of an interlocking cam that is interlocked by a temperature-responsive member. respectively form a starting cam surface and a warm-up cam surface that selectively engage with the engaging pin of the operating lever, and a predetermined position of the carburetor body is provided with the engaging pin of the operating lever when starting the engine. A diaphragm device is provided with a diaphragm device that holds the operating lever at a position where it contacts the starting cam surface and that moves backward when the engine negative pressure reaches a predetermined value or more, and that the actuating rod moves backward. Further, when the actuating lever is rotated in the valve closing direction by the biasing force of the return spring of the throttle valve, the engagement pin of the lever is configured to come into contact with the warm-up cam surface. A fast idle device for a carburetor, characterized by: