JPS6138343B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a negative pressure regulating device for an exhaust recirculation control valve that operates with negative pressure in an internal combustion engine, particularly in an intake system.

Generally, in exhaust gas recirculation (hereinafter referred to as EGR) equipment, as the EGR rate increases,
Although the NOx reduction effect increases, drivability and fuel efficiency also deteriorate, so EGR control that is well-balanced depending on the engine operating status is required.

Normal EGR control is performed depending on the operating state by an EGR valve that operates using negative pressure generated in the intake system as a signal pressure.

By the way, it is generally preferable not to perform EGR when the engine is at low temperature or extremely high temperature from the viewpoint of promoting warm-up and engine output characteristics. Conventionally, in such cases, EGR is performed by diluting the operating negative pressure with the atmosphere or cutting it off. (References, Japanese Unexamined Patent Application Publication No. 1989-1999)
Publication No. 88416).

In order to control the operating negative pressure of the EGR valve in this way, conventionally, a negative pressure regulator having a solenoid valve or diaphragm valve that is activated via an engine temperature detection means is inserted in the EGR valve operating negative pressure passage. However, these had complicated structures, poor valve sealing, and lacked reliability, so there was a desire for a negative pressure regulator with a simpler structure and reliable operation.

The present invention has been proposed in view of these points, and uses a thermowax that responds to the engine cooling water temperature to reliably control the operating negative pressure by diluting it with outside air at the appropriate time. The purpose is to provide a pressure regulating device.

Embodiments of the present invention will be described below based on the drawings.

In Fig. 1, 1 is the engine body, 2 is the carburetor body, 3 is the throttle valve, 4 is the intake pipe, 5 is the exhaust pipe, and 6
is an exhaust gas recirculation passage (EGR passage), 7 is an exhaust recirculation control valve (EGR valve), and 8 is an EGR valve operation negative pressure passage,
A negative pressure regulating device 10 is attached to the negative pressure passage 8 to control the operating negative pressure of the EGR valve 7 by introducing outside air at an appropriate time depending on the engine temperature.

As shown in FIGS. 2 and 3, the negative pressure regulating device 10 includes a case 11 that protrudes into the jacket 9 and has a wax pellet built therein to detect the temperature of the cooling water in the jacket 9, which is a parameter of the engine temperature. On the axis of the rod 13, which moves forward and backward as the wax pellets in the outer casing 12 expand and contract, two valves, a first valve 14 and a second valve 15, which control the introduction and cutoff of outside air, are spaced at appropriate intervals. A valve seat portion 16 integrally formed with the casing 12 is interposed between the two valves 14 and 15.

The first valve 14 is slidably fitted into the rod 13, and is normally pressed against a stopper 18 at the tip of the rod 13 by a set spring 17.
However, after the rod 13 comes into contact with the valve seat 16 during operation on the extension side, the valve is maintained in the closed state as it is, and only the rod 13 thereafter extends while contracting the spring 17. It's getting old.

The second valve 15 is opened from the valve seat portion 1 from the cover body 21 side having the outside air inlet 20 via the filter 19.
6 by a set spring 22. Then, an adjusting screw 23 for adjusting the contact timing is inserted through the center of the second valve 15 in the axial direction, and the rod 13 extends and the adjusting screw 23
By contacting and further pressing down, the second valve 15 is separated from the valve seat portion 16.

The valve seat portion 16 has an insertion hole 24 for the rod 13 in the center, and negative pressure leak passages 25 are provided on both sides of the valve seat portion 16 at positions corresponding to the valve seat portions 14a and 15a of the valves 14 and 15, respectively, passing through the valve seat portion 16 in the axial direction. and an outside air passage 26 are formed.

The negative pressure leak passage 25 communicates with the aforementioned negative pressure passage 8 via a nipple 27, and the outside air passage 26 has a notch 28 formed in the valve seat 16, which is connected to the outside air passage 26 regardless of whether the second valve 15 is opened or closed. outside air inlet 20
Outside air is flowing in.

Therefore, when outside air is introduced into the negative pressure leak passage 25, the second valve 15 is closed and the first valve 14 is closed.
is open, or when the first valve 14 is closed and the second valve 15 is open, and when both the first valve 14 and the second valve 15 are closed, the negative pressure leak passage 25 is filled with outside air. is no longer being introduced.

In addition, 29 in the figure is a return spring of the rod 13.

Next, the operation of the present invention will be explained.

In FIG. 1, a part of the exhaust gas is recirculated to the intake pipe 4 via an EGR passage 6 communicating with the exhaust pipe 5, depending on the opening degree of the EGR valve 7 which is activated by a negative pressure signal. During warm-up operation when the cooling water temperature is low, for example, when the water temperature is less than 60° C., the negative pressure regulator 10 is in the state shown in FIG. It communicates with the negative pressure leak passage 25 and the negative pressure passage 8 to dilute the operating negative pressure of the EGR valve 7 with the atmosphere.
EGR amount is reduced or cut.

After warming up, when the water temperature reaches 60°C or more, the wax pellet expands and the rod 13 moves to the extension side against the return spring 29, as shown in FIG. and the first valve seat 16a of the valve seat portion 16 are in contact with each other,
Since the negative pressure leak passage 25 is closed (the second valve 15 is still closed in this state), the amount of leak air is blocked, and the EGR valve 7 is operated by the negative pressure according to the opening degree of the carburetor throttle valve 3. (However, if the operation of EGR valve 7 is controlled by VC negative pressure).

Furthermore, as the high-load operation continues and the cooling water temperature rises, only the rod 13 descends through the insertion hole 24 of the valve seat 16, as shown in FIG.
When the adjustment screw 23 of the valve 15 is contacted and pushed down, the valve seat portion 15a of the second valve 15 is separated from the second valve seat 16b of the valve seat portion 16, and the negative pressure leak passage 25 is opened again. Air leaks out and the EGR valve 7 operates to reduce or cut the EGR amount.

In this way, the EGR negative pressure control signal is derived from between the first valve seat 16a that engages with the first valve 14 and the second valve seat 16b that engages with the second valve 15. When one side is open,
Since we reduced or cut the amount of EGR,
The passage within the device 10 can be shortened and simplified, and durability is improved.

In addition, the negative pressure leak passage 25 is branched from the negative pressure passage 8 of the EGR valve 7, and the device 10 is built into it, so that there is no leakage in the engine room.
The arrangement of the entire EGR device becomes easy.

Furthermore, if you want to control two or more EGR valves 7 simultaneously and independently, you can easily and accurately control two or more EGR valves 7 by adding a negative pressure leak passage 25' to the valve seat 16 as shown in FIG. It is possible to control it well.

As explained above, the present invention derives a control signal for controlling EGR negative pressure from between the first valve seat that engages the first valve and the second valve seat that engages the second valve, and When one of the two valves is open,
By reducing or cutting the amount of EGR, the passage inside the negative pressure regulator can be shortened and simplified, further improving reliability and durability. Also,
Its operation becomes reliable and stable, and it has the effect of controlling the negative pressure of the EGR valve with high precision.

Furthermore, since the structure is relatively simple, costs can be reduced and the reliability of the device can also be increased.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of the present invention, Fig. 2 is a cross-sectional view of the main parts of the present invention, Fig. 3 is a cross-sectional view taken along the - line in Fig. 2, and Figs. 4 and 5 are each main part showing the operating state. FIG. 6 is a sectional view showing another embodiment. 7... EGR valve, 8... Negative pressure passage, 10... Negative pressure regulator, 11... Wax pellet built-in case, 13... Rod, 14... First valve, 15
...Second valve, 25...Negative pressure leak passage, 26
...Outside air passage, 16... Valve seat portion, 24... Rod insertion hole, 25'... Negative pressure leak passage.

Claims (1)

[Claims] 1. In the negative pressure adjustment device that is installed in the negative pressure passage that supplies operating negative pressure to the exhaust recirculation control valve and dilutes the operating negative pressure with the atmosphere depending on the engine temperature, a rod that responds to the thermowax that senses the engine cooling water temperature. and,
Two valves are arranged at intervals in the axial direction of the rod and open and close in stages as the rod expands and contracts. a valve seat that communicates the negative pressure passage with the atmosphere at high temperatures when only the valve opens; the valve seat is connected to a negative pressure leak passage that communicates with the negative pressure passage; an outside air passage that communicates with the atmosphere; The exhaust gas is provided so as to extend through the exhaust passage in the axial direction, and is configured such that one end of the leak passage and the outside air passage are simultaneously closed by the first valve, and only the other end of the leak passage is closed by the second valve. Negative pressure adjustment device for reflux mechanism.