JPS6347330Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is applicable to diesel engines, for example.
This invention relates to a negative pressure control valve that controls the negative pressure of an EGR valve.

Diesel engines require various exhaust gas countermeasures. For example, an EGR passage is formed between the exhaust system and intake system of a diesel engine, and this EGR passage is controlled by the load condition using an EGR valve. The idea is to control the situation accordingly.

However, unlike gasoline engines, diesel engines do not have a negative pressure source that changes depending on the load;
In order to control the EGR valve, a negative pressure control valve that can change the amount of negative pressure depending on the load condition is used.
It has been considered to control the opening and closing of the EGR valve using this negative pressure control valve.

This idea was developed in consideration of the above points, and for example, the negative pressure is controlled according to the operating condition and load condition of the diesel engine, and the EGR valve is driven and controlled, making it possible to effectively implement exhaust gas countermeasures. The present invention aims to provide a negative pressure control valve that does the following.

That is, the negative pressure control valve according to this invention supports a valve holding member on a diaphragm that partitions a diaphragm chamber having a negative pressure intake port and a negative pressure outlet port and an atmospheric release chamber, and also has a valve holding member that is integrated with the valve holding member. A moving rod is installed in which an attraction force is applied by excitation control, and the excitation action is controlled depending on the load condition, etc., to maintain an equilibrium relationship between the negative pressure in the diaphragm chamber and the attraction force, and to selectively hold the valve. The member is configured so that the diaphragm chamber and the atmosphere open chamber are communicated with each other.

An embodiment of this invention will be described below with reference to the drawings. Figure 1 shows its configuration.
is an EGR-controlled diesel engine,
This diesel engine 11 has a fuel injection nozzle 1
2 is provided toward the inside of the cylinder, and this cylinder is communicated with an exhaust system 14 and an intake system 13 via a valve. The exhaust system 14 and the intake system 13 are connected to the EGR passage 1 via an exhaust gas control valve 15.
They are connected by 6a and 16b. Exhaust gas control valve 1
5 includes a diaphragm chamber 18 partitioned by a diaphragm 17, and a valve body 1 that opens and closes the EGR passage 16b according to the negative pressure within the diaphragm chamber 18.
9 and performs EGR control of the diesel engine 11. Then, the negative pressure control of the diaphragm chamber 18 of the exhaust gas control valve 15 is performed by the negative pressure control valve 20.

This negative pressure control valve 20 has an outer wall constituted by a housing 21, a cover 22, a yoke 23, and a magnetic plate 24. A diaphragm 25 is sandwiched between the housing 21 and the cover 22, and Two chambers are formed corresponding to the housing 21 part and the cover 22 part, respectively. That is, the diaphragm 25 and the cover 22 form a diaphragm chamber 26, and the diaphragm chamber 26 is provided with a negative pressure intake port 27 and a negative pressure outlet port 28. The negative pressure outlet port 28 communicates with the diaphragm chamber 18 of the exhaust gas control valve 15 via a passage 29. Also, negative pressure intake port 2
7 is connected to a vacuum pump 31 via a passage 30, and is configured to supply negative pressure to the diaphragm chamber 26.

The diaphragm 25 carries a valve holding member 32 in its central portion. This valve holding member 32 is formed with a passage that passes through both sides of the diaphragm 25, and this passage is connected to the diaphragm chamber 2.
It is constructed by making steps in the middle so that the diameter is smaller in six directions. The stepped portion acts as a valve seat 32a, and a movable valve body 33 installed in the large diameter portion of the passage is brought into contact with the valve seat 32a, so as to close the passage. In this case, the movable valve body 33 is in pressure contact with the valve seat by the spring 34. Further, the tip of the negative pressure intake port 27 is extended and introduced into the small diameter portion of the passage of the valve holding member 32, and the tip opening functions as a valve seat 27a.

That is, when the valve holding member 32 is positioned downward as shown in the figure, the elasticity of the spring 34 causes the movable valve body 33 to close the passage passing through both sides of the diaphragm 25. On the other hand, when the negative pressure in the diaphragm chamber 26 increases and the valve holding member 32 rises in the figure together with the diaphragm 25, the movable valve body 33 hits the valve seat 27a of the negative pressure intake port 27, and this negative pressure intake When the port 27 is closed and the valve holding member 32 is further raised, the movable valve body 33 is separated from the valve seat 32a of the stepped portion in the valve holding member 32 and opens its passage, allowing both sides of the diaphragm 25 to communicate with each other. It becomes like this. Further, the valve holding member 32 is provided with an opening 44 that communicates with the atmosphere open chamber 35, and the movable valve body 33 communicates with the open atmosphere chamber 35 that is opened away from the valve seat 32a.

The portion of the diaphragm 25 surrounded by the housing 21 is an atmosphere open chamber 35, and the housing 21 has an opening 36 that opens the inside thereof to the atmosphere. That is, the diaphragm chamber 26 and the atmosphere opening chamber 35 are selectively communicated with each other in response to the vertical movement of the valve holding member 32 supported by the diaphragm 25.

A moving rod 37 is integrally provided on the valve holding member 32 so as to extend in the direction of the atmosphere opening chamber 35. This moving rod 37 is
A status core 38 is provided on the outer periphery of the moving rod 37 with a small gap therebetween. An excitation coil 39 is wound around the outer periphery of the status core 38. A magnetic plate 24 is set above the excitation coil 39 so as to be integrated with the yoke 23, and a moving core 40 is provided on the outer periphery of the moving rod 37 in accordance with the position of the magnetic plate 24. are integrally provided. And this moving core 40 and status core 3
A gap 41 is set between the excitation coil 3 and the excitation coil 3.
The magnetic attraction force according to the excitation current supplied to 9,
A suction force is applied to the gap 41 to suck the moving rod 37 downward and increase the negative pressure in the diaphragm chamber 26 on the valve holding member 32, that is, on the diaphragm 25. so that This suction force and the negative pressure within the diaphragm chamber 26 are balanced.

42 is a load sensor, and a signal corresponding to the load state detected by this sensor 42 is supplied to a processing circuit 43 such as a computer, and this processing circuit 43 controls the excitation current to the excitation coil 39.

That is, in the negative pressure control valve 20 configured as described above, when the load increases, for example, the load sensor 42 generates a detection signal corresponding to the amount of load. This detection signal is processed by the processing circuit 43, and as the load increases, the excitation current to the excitation coil 39 is controlled to be reduced, thereby controlling the attraction force to the moving core 40.

This suction force to the moving core 40, that is, the valve holding member 3 is applied via the moving rod 37.
Due to the suction force acting on the diaphragm 2, the negative pressure within the diaphragm chamber shifts to a level that is in balance with this suction force. When the negative pressure in the diaphragm chamber 26 is small, the valve holding member 32 is in the state shown in the figure, and the passage of the valve holding member 32 is closed by the movable valve body 33. The diaphragm chamber 26 is connected to the vacuum pump 3.
1, the negative pressure rises, and in a state where the negative pressure overcomes the magnetic attraction force, the valve holding member 32 rises. That is, the movable valve body 33 is opened, the valve seat 33a of the negative pressure intake port 27 is closed, the diaphragm chamber 26 is communicated with the atmosphere opening chamber 35, and the negative pressure in the diaphragm chamber 26 is reduced. .

That is, the magnetic attraction force to the moving core 40 is set according to the state of the load, and the negative pressure state of the diaphragm chamber 26 is variably set in a state that is balanced with the attraction force. Therefore, the valve body 19 of the exhaust gas control valve 15 is controlled according to the load condition, and the passage 16b is controlled to open and close to connect the exhaust system of the diesel engine 11 to the intake system.
Control will be automatic.

Here, in the negative pressure control valve 20, the tip of the moving core 40 that is magnetically controlled to attract
If the gap is straight as shown in the figure, the attraction characteristic of the gap 41 with respect to the excitation current will be as shown in FIG. That is, gap 41
When is narrow as indicated by A, the increase in attractive force per unit current becomes large. In the figure, a is the current value
The characteristics are shown when 0.1A, b is 0.2A, and c is 0.3A.

Therefore, in the case where the set value of the gap 41 is A in FIG. 2 and in the case where it is wider than B, the relationship between the negative pressure in the diaphragm chamber 26 and the current value is as shown in A and B in FIG. 3, respectively. The characteristic is shown by B, and when the gap 41 is narrow, the negative pressure changes with a large slope with respect to the current. That is, by adjusting the position of the moving core 40 with respect to the status core 38 and setting the gap 41, the negative pressure change control characteristic of the diaphragm chamber 26 with respect to the excitation current supplied to the excitation coil 39 can be adjusted to a desired value. .

Further, the tip of the moving core 40 is formed into a tapered shape as shown by a broken line 40a in FIG.
If the moving core 40 is shaped so that the distance from the magnetic plate 24 increases in the direction of its distal end, the suction characteristics for the moving core 40 will be as shown in FIG. That is, gap 41
Even if the lengths of A and B are different, the increase in attractive force per unit current remains the same. Therefore, the negative pressure change characteristic of the diaphragm chamber 26 with respect to the current value has a constant slope as shown in FIG. 5, and the control characteristics of the negative pressure control valve 20 can be easily made uniform.

Here, the load detection signal from the load sensor 42 is controlled by a processing circuit 43 having an arithmetic mechanism such as a computer so that the excitation current to the excitation coil 39 is increased as the engine load becomes smaller. Therefore, when the engine load is small, the relatively high negative pressure in the diaphragm chamber 26 acts on the diaphragm chamber 18 of the exhaust gas control valve 15, opening the valve body 19 and allowing a large amount of exhaust gas to return to the intake system 13. and then subjected to reburning.

As described above, according to this invention, EGR control, which is one of the exhaust gas countermeasures for diesel engines, can be performed by controlling the magnetic attraction force according to the operating load condition of the engine. This can be effectively implemented by a control valve, and its practical effects are significant.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional configuration diagram showing a negative pressure control valve according to an embodiment of this invention in relation to EGR control of a diesel engine, and Figure 2 shows the first shape of the moving core in the negative pressure control valve. Figure 3 is a diagram showing the relationship between the gap length and attraction force, Figure 3 is a diagram showing the relationship between current output and load in the state of Figure 2,
This figure is a diagram showing the attraction force characteristics in the second shape of the moving core, and FIG. 5 is a diagram showing the current and output load characteristics in the state of FIG. 4. 11... Diesel engine, 15... Exhaust gas control valve, 20... Negative pressure control valve, 21... Housing, 22... Cover, 25... Diaphragm,
26... Diaphragm chamber, 27... Negative pressure intake port, 28... Negative pressure outlet port, 31... Vacuum pump, 32... Valve holding member, 33... Movable valve body, 35... Atmospheric release chamber, 37... Moving rod, 38... Status core, 39... Excitation coil, 40... Moving core, 41... Gap, 42... Load sensor.

Claims (1)

[Claims for Utility Model Registration] A diaphragm chamber composed of a diaphragm and a cover and equipped with a negative pressure intake port and a negative pressure outlet port, and a diaphragm chamber adjacent to the diaphragm chamber via the diaphragm, and the diaphragm and the housing. a pressure chamber formed by a pressure chamber; a valve holding member supported by the diaphragm; and a valve holding member provided integrally with the valve holding member, which is attracted to the diaphragm through the valve holding member by an excitation suction operation by a moving core and a coil. a moving rod that applies a force; and a moving rod that is held by the valve holding member and operates as the valve holding member moves due to an increase in negative pressure in the diaphragm chamber, thereby communicating the diaphragm chamber and the pressure chamber. a movable valve body, the position of the valve holding member is set in a balanced relationship between the suction force by the moving rod and the force acting on the diaphragm due to negative pressure of the diaphragm, and the movable valve body is actuated. A negative pressure control valve characterized in that it is configured to