JPS6148030B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air switching valve for controlling the supply of secondary air to an exhaust system of an engine in a secondary air supply system for an automobile engine.

As is well known, the secondary air supply system introduces secondary air pumped from an air pump into the exhaust system in order to re-react CO and HC that could not be sufficiently purified in the combustion chamber in the exhaust system. It is something to do. The air switching valve, which forms the heart of the system, has the function of supplying secondary air to the exhaust system (usually an exhaust port) or switching it to an air cleaner, etc., depending on the operating state of the engine.

Incidentally, the air pump is a pump for supplying secondary air necessary for re-combustion, and is driven by an engine to draw in fresh air, pressurize it, and discharge it to the exhaust system. For this reason, the air switching valve is generally equipped with a relief valve in order to provide relief to the air cleaner when the engine speed increases, mainly during acceleration, and the air pressure from the air pump increases even if the air is fully supplied to the exhaust system. There is.

However, as shown in Figure 1, conventional air switching valves have separate flow control valves that switch and control air supply to the exhaust system and air cleaner, and a relief valve that releases air to the air cleaner when the air chamber rises. They are arranged so that they each operate independently. Therefore, it is difficult to design the device to be compact, and when it is installed in a system, it requires a large installation space, which is disadvantageous.Also, the opening and closing operations of the control valve and relief valve occur at the same time. There was also the problem that the operating durability was significantly reduced due to the shock load.

Therefore, the technical object of the present invention is to make the flow rate control valve and the relief valve operate in conjunction with each other.

The technical means taken to solve the above technical problem is to provide a pressure chamber in the body that communicates with the input port, output port, and relief port, and respond to a negative pressure signal in the signal chamber to connect the pressure chamber and the output port. The communication between the ports is controlled to open and close by a control valve, the communication between the pressure chamber and the relief port is controlled to open and close by a relief valve, the relief valve is normally biased in the closing direction by a spring means, and furthermore, when the control valve is closed, The control valve and the relief valve are operatively connected by a rod means so that the relief valve is always open.

In the above technical means, when the control valve is closed and the air supply to the exhaust system is cut off, the movement of the control valve is transmitted to the relief valve through the rod means, the relief valve opens, and the secondary air from the air pump is Air is relieved to the air cleaner. When the control valve is open, the relief valve is closed, but when the air pressure in the pressure chamber exceeds a predetermined value, the relief valve itself senses the air pressure and opens regardless of the movement of the rod means. Therefore, only one signal chamber is required to operate the control valve.

Now, as an example of this type of air switching valve, conventionally,
The one described in Japanese Utility Model Application Publication No. 51-28824 is known. However, in the conventional device, a control valve that controls opening and closing of the passage to the exhaust system,
Relief valves that control the opening and closing of passages to the air cleaner are each actuated in response to movement of shafts connected to the diaphragm. Therefore,
Since the two valves are actuated only by the shaft, each of the two valves requires a signal chamber. Therefore, it is difficult to accurately and reliably control the operation of the shaft using the signal pressures supplied to the two signal chambers, making it insufficient to ensure operational reliability. Furthermore, since two signal rooms are required, the configuration of the signal room becomes complicated. In contrast, these problems do not exist in the present invention.

An embodiment according to the present invention will be described below with reference to the accompanying drawings. In the air switching valve 10 shown in FIG.
Body 12 and atmospheric port 13 are output port 1
A second body 15 having an input port 16, a third body 17 having an input port 16, and a fourth body 19 having a relief port 18 are each integrally coupled in an airtight manner. The diaphragm 20 has its outer peripheral portion airtightly clamped between the first and second bodies 12 and 15, and its center portion between the two plates 21 and 2.
2, and its inner peripheral portion is hermetically fixed to the diaphragm piston 23. A signal chamber 2 is provided in the first body 12 with the diaphragm 20 as a border.
4, an atmospheric chamber 25 is formed in the second body 15, respectively. The atmospheric chamber 25 is separated from a chamber 26 by a blocking wall 15a extending from the second body 15. Further, a pressure chamber 27 is provided in the third body 17.
Relief chambers 28 are formed within the body 19, respectively. The signal chamber 24 communicates via the signal port 11 with a signal negative pressure source that generates a negative pressure signal depending on the operating state of the engine, such as an engine intake manifold (not shown). The atmospheric chamber 25 communicates with the atmosphere via the atmospheric port 13.
The pressure chamber 27 communicates with an air pump (not shown) via the input port 16, and the air pump is driven by the engine as described above, sucks fresh air from the air cleaner, pressurizes it, and discharges it to the input port 16. It is something. The chamber 26 communicates via the output port 14 with an engine exhaust system, such as an exhaust port (not shown). The relief chamber 28 communicates with an air cleaner (not shown) via the relief port 18.

A guide member 29 having a low coefficient of friction is inserted and fixed into the inner periphery flange portion 15b of the blocking wall 15a, and the diaphragm piston 23 can slide on the inner periphery of the guide member 29. Signal room 2
A spring 30, one end of which is secured to the first body 12, is tensioned within the diaphragm piston 4, and the other end of the spring 30 constantly urges the diaphragm piston 23 downward in the drawing. The control valve 31 formed integrally with the diaphragm piston 23 is connected to the input port 16.
It controls opening and closing of communication between the output port 14 and the output port 14. In other words, the control valve 31 normally has a spring 3
The diaphragm contacts the valve seat 17a formed in the third body 17 and is held in the closed position by the urging force of 0, and when the negative pressure introduced into the signal chamber 24 increases and reaches a predetermined value, it overcomes the force of the spring 24 and closes the diaphragm. Since the piston 23 moves upward in the drawing, it is separated from the valve seat 17a and held in the open position. On the other hand, the relief valve 32 accommodated in the relief chamber 28
, which controls the opening and closing of communication between the pressure chamber 27 and the relief chamber 28, and is always urged upward in the figure to the closed position by the urging force of a spring 34 stretched between the fourth body 19 and the retainer 33. In the closed position, a valve portion 32a made of a rubber material of the relief valve 32 comes into contact with a valve seat 17b formed on the third body 17. In other words, the relief valve 32 is normally closed by the biasing force of the spring 34 when the control valve 31 is held in the open position, but when the air pressure discharged into the pressure chamber 27 exceeds a predetermined value, the biasing force of the spring 34 When the control valve 31 is held in the closed position, the relief valve 32 is urged downward in the drawing by the rod 35 integrated with the control valve 31 and is always held in the open position. In other words, the rod 35 constitutes interlocking means for operatively interlocking the control valve 31 and the relief valve 32.

In the embodiment of the above configuration, the operation thereof will be explained next. First, during normal engine operation, the intake manifold negative pressure is in the signal chamber 24.
The negative pressure causes the diaphragm piston 23 to overcome the biasing force of the spring 30 and move upward in the figure, so that the control valve 31 opens. As a result, the secondary air pumped from the air pump is supplied to the exhaust port of the engine via the input port 16, the pressure chamber 27, and the output port 14.
Now, in this state, for example during acceleration, the engine speed increases and even if air is completely supplied to the exhaust port, the air pressure from the air pump still increases, and if the air pressure in the pressure chamber 27 exceeds a predetermined value, the relief will occur. The valve 32 opens and the air is relieved through the relief chamber 28 and the relief port 18 to the air cleaner.

Next, when the engine is operated under high load, the negative pressure in the intake manifold becomes low, so the control valve 31 is closed by the biasing force of the spring 30. At this time, the relief valve 32 overcomes the urging force of the spring 34 and opens by the rod 35 integrated with the control valve 31. As a result, the secondary air pumped from the air pump flows into the pressure chamber 27 and the relief chamber 28.
and is relieved to the air cleaner via the relief port 18.

As described in detail above, in the air switching valve according to the present invention, when the control valve 31 is closed and the supply to the exhaust port is cut off, the rod that operatively interlocks the control valve 31 and the relief valve 32 is used. 35 opens the relief valve 32, and the secondary air from the air pump is relieved to the air cleaner. In other words, the relief valve 32 also functions as a flow rate control valve for the air cleaner. Therefore, it is possible to reduce the size of the air switching valve device, and the space required for the secondary air supply system is also reduced, greatly improving the ease of assembly. Also,
If both the control valve 31 and the relief valve 32 are supported only by the loads of the springs 30 and 34 as in this embodiment, the impact load when the valves 31 and 32 are opened and closed can be greatly reduced. The durability of can be significantly improved.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional air switching valve, Figure 2 is a sectional view showing a conventional air switching valve.
The figure is a sectional view showing an embodiment of the air switching valve according to the present invention. Note that the same reference numerals in the figures indicate the same or equivalent parts. 10: Air switching valve, 14: Output port, 16:
Input port, 18: Relief port, 20: Diaphragm, 24: Signal chamber, 27: Pressure chamber, 28:
relief chamber, 31: control valve, 32: relief valve,
34: Spring, 35: Rod.

Claims (1)

[Claims] 1 A body having a signal port communicating with the intake system of the engine, an input port communicating with the air pump, an output port communicating with the exhaust system of the engine, and a relief port communicating with the air cleaner; A pressure chamber that communicates with the output port and the relief port, a signal chamber that communicates with the signal port and is partitioned by a diaphragm, and a signal chamber that senses a negative pressure signal introduced into the signal chamber and operates in conjunction with the diaphragm to communicate with the pressure chamber. A control valve that controls opening and closing of communication with the output port, a relief valve that controls opening and closing of communication between the pressure chamber and the relief port, and when the air pressure in the pressure chamber is below a predetermined value when the control valve is opened. a spring means that always biases the relief valve in the closing direction so as to close the relief valve and open the relief valve when the air pressure is equal to or higher than a predetermined value; An air switching valve in a secondary air supply system having rod means operatively connecting a control valve and a relief valve so that the control valve and the relief valve are always open.