JPH048265Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to an intake throttle control device for a diesel engine, and more particularly to an intake throttle control device in which an intake throttle valve is provided in an intake passage and the intake throttle valve is opened and closed by an actuator operated by negative pressure. The present invention relates to an aperture control device. [Conventional technology] Conventionally, vibrations in diesel engines,
As a noise countermeasure, it is known that it is effective to throttle the amount of intake air depending on the operating state of the engine (for example, Japanese Patent Application Laid-Open No. 58-35241). Conventional intake throttle control basically relies on a system as shown in FIG. That is, an intake throttle valve 72 is provided in the intake passage 71, and the intake throttle valve 72 is provided in the intake passage 71.
2 is connected to a diaphragm device 73 as an actuator operated by negative pressure. pressure is introduced. The negative pressure introduction passage 76 is equipped with a vacuum switching valve (hereinafter referred to as VSV) as a switching valve.
77 is provided, and communication from the VSV 77 to the diaphragm device 73 is switched to the vacuum tank side port 79 and the atmospheric air introduction port 80 according to engine operating conditions based on signals from the CPU 78 and the like. The pressure introduced into the diaphragm device 73 is
The intake throttle valve 72 is closed when negative pressure is applied from the vacuum tank 75 side, and opened when the air is released to the atmosphere. In addition to the above-mentioned vibration countermeasures, the intake throttle valve 72 is throttled in the idling or light load range from the viewpoint of exhaust gas countermeasures and fuel efficiency. [Problems to be solved by the invention] In the conventional system as described above, by turning on and off the negative pressure introduced into the diaphragm device 73, the intake throttle valve 72 is turned on and off according to various operating conditions.
However, when the negative pressure introduced is off, the negative pressure introduction passage to the diaphragm device 73 and the diaphragm chamber are completely opened to the atmosphere, so this area is at or near atmospheric pressure. Negative pressure decreases. Therefore, when the introduction negative pressure is turned on next and the diaphragm device 73 and the vacuum tank 75 side are communicated, atmospheric pressure remains in the above part, so the negative pressure on the vacuum tank 75 side is affected by the atmospheric pressure. will drop significantly. When such ON/OFF control of the VSV 77 is repeated, the negative pressure in the vacuum tank 75 drops sharply, so to compensate for this, the vacuum pump 74 has to be operated more frequently, causing the problem of increased electrical load. be. An increase in electrical load leads to a decrease in fuel efficiency. Further, it takes time to increase the negative pressure in the vacuum tank 75 to a certain value or higher, that is, to a negative pressure sufficient to open the intake throttle valve 72, and therefore the operation of the intake throttle valve 72 may be delayed. This invention focuses on the above-mentioned problems, and aims to suppress as much as possible the negative pressure led to the intake throttle valve actuator from dropping more than necessary, improve the intake throttle valve actuation response, and reduce the frequency of vacuum pump operation. The purpose is to reduce the electrical load by reducing the electrical load, thereby improving fuel efficiency. [Means for Solving the Problems] The intake throttle control device for a diesel engine according to the present invention, which meets this objective, provides an intake throttle valve in the intake passage of the diesel engine, and controls the intake throttle valve by introducing negative pressure. An actuator that operates in the closing direction is connected to the intake throttle valve, a negative pressure introduction passage from a vacuum tank in which negative pressure is accumulated by a vacuum pump is connected to the actuator, and the actuator is connected to the negative pressure introduction passage. In a diesel engine intake throttle control device that is equipped with a switching valve that switches the pressure introduced into the vacuum pump between negative pressure on the vacuum pump side and atmospheric pressure, the pressure in the passage is connected to the negative pressure introduction passage from the switching valve to the actuator. A detectable pressure detection means is provided, and the negative pressure in the negative pressure introduction passage from the switching valve to the actuator is set to be equal to or lower than the intake throttle valve opening negative pressure based on the signal from the pressure detection means at the atmosphere introduction port of the switching valve. It is equipped with a shutoff valve that shuts off the switching valve from communicating with the atmosphere when the temperature drops to a certain value. Here, the pressure detection means consists of, for example, a pressure switch that outputs an output when the negative pressure exceeds a certain set value, and the cutoff valve consists of a simple on-off valve operated by VSV or an electric signal. [Function] In such a device, when opening the intake throttle valve, the switching valve is switched to the atmosphere introduction port side, and atmospheric pressure is introduced into the actuator and the negative pressure introduction passage to the actuator. but,
When the pressure in this negative pressure introduction passage decreases to a negative pressure set value low enough to open the intake throttle valve, that pressure is detected by the pressure detection means, and the shutoff valve is actuated based on the pressure, and the switching valve is opened. The introduction port is closed. Therefore, no more atmospheric pressure is introduced into the negative pressure introduction passage, and a drop in negative pressure below the set pressure is suppressed. Even if the switching valve is switched to the vacuum tank side in order to close the intake throttle valve from this state, the negative pressure of the above set pressure will remain in the negative pressure introduction passage from the switching valve to the actuator and in the actuator. Since it remains, a large drop in negative pressure on the vacuum tank side can be suppressed. As a result, the frequency of operation of the vacuum pump is reduced, and the electrical load is reduced. Further, since negative pressure remains in the negative pressure introduction passage and the actuator, it takes only a short time to increase the negative pressure to the level required to close the intake throttle valve, and the responsiveness of the valve opening/closing operation is improved. [Embodiments] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 1 and 2 show an intake throttle control device for a diesel engine according to a first embodiment of the present invention. In the figure, 1 is an engine, 1a is its intake manifold, 1b is an exhaust manifold, and 1c is a fuel injection valve. An idler thrust screw 3 is provided in the intake manifold 1a, and in the intake passage,
An intake throttle valve 2 is provided. A diaphragm device 5 serving as an actuator for opening and closing the intake throttle valve 2 is connected to the intake throttle valve 2 via a throttle valve link 4 . This diaphragm device 5 operates in the direction of closing the intake throttle valve 2 by the negative pressure introduced from the vacuum pump 6 and the vacuum tank 7 that accumulates its negative pressure. The vacuum pump 6 and the vacuum tank 7 are
connected by a conduit 25 to the vacuum tank 7
A vacuum switch 8 is provided, and a battery 10 is connected via a relay 9 to the vacuum switch 8 and the vacuum pump 6 by conductive wires 16 and 15. The conduit 25 is connected to the conduit 22 as a negative pressure introduction passage,
It is connected to the diaphragm device 5 via 21, and a switching valve 11 is interposed between the conduit 22 and the conduit 21. The switching valve 11 is composed of a VSV, and based on the signal 11b from the ECU 50, communicates with the conduit 21 (that is, the pressure introduced into the diaphragm device 5) between the conduit 22 side (that is, the vacuum tank 7 side) and the atmospheric pressure side. It is now possible to switch to Another VSV 12 serving as a cutoff valve is connected to this atmospheric air introduction port 11a via a conduit 24. The cutoff valve 12 is also provided with an atmospheric air introduction port 12a equipped with a filter. A pressure switch 13 as a pressure detection means is provided in a conduit 21, which is a negative pressure introduction passage from the switching valve 11 to the diaphragm device 5, via a branch conduit 23. The pressure switch 13 is designed to output an output when the negative pressure in the negative pressure introduction passage 21 becomes other than the set value, and the output is connected to the conductor 14.
is inputted to the cutoff valve 12 by. The ECU 50 includes a rotational speed sensor 40, an intake air temperature sensor 41, a water temperature sensor 42, a pressure sensor 43 connected to a conduit 26 for sensing the intake pressure of the intake manifold 1a, and an accelerator position sensor 45 that interlocks with the accelerator pedal 44. The signal of
Conductive wires 40a, 41a, 42a, 43a, 45 respectively
It is input via a.

[Table] Next, when even one of the above operating conditions is not satisfied, the switching valve 11 is turned off, atmospheric air is introduced from the atmospheric air introduction port 11a, and the negative pressure in the conduit 21 gradually decreases. However, a vacuum switch 13 is provided at the other end of the conduit 23 branched from the conduit 21, and when the negative pressure in the conduit 21 decreases and the vacuum switch 13 reaches the set pressure, the vacuum switch 13 turns on and switches. The electric charge of the valve 11 is output. As a result, the shutoff valve 12 is turned on, stopping the introduction of air from the air introduction port 12a, and as a result, stopping the introduction of air into the air introduction port 11a of the switching valve 11. Even if the introduction of atmospheric air is stopped, the negative pressure introduced into the diaphragm device 5 is low enough to open the valve 2, so the intake throttle valve 2 is opened. The above conditions can be summarized as shown in Table 2, for example.

[Table] Next, the operation of the above control will be explained. In the conventional method, the switching valve is turned off, the inside of the conduit 21 is opened to the atmosphere, and the negative pressure inside the conduit 21 and the diaphragm device 5 becomes approximately atmospheric pressure. Therefore, when the switching valve is turned on and the conduit 21 and the conduit 22 communicate with each other, the negative pressure inside the vacuum tank is reduced to the conduit 21.
Then, the volume of the diaphragm chamber is greatly reduced, and the vacuum switch 8 is turned on, activating the relay 9, and applying an electric charge to the vacuum pump 6 to turn it. Since the vacuum pump 6 is operated every time such a state is repeated, the electrical load increases and fuel efficiency deteriorates. However, in the present invention, as shown in Table 2, a certain amount of negative pressure remains in the conduit 21 and the diaphragm chamber (however, the residual pressure is less than the set pressure sufficient to open the intake throttle valve). ), even when the switching valve 11 is turned on and the conduits 21 and 22 communicate with each other, the drop in negative pressure in the vacuum tank 7 is suppressed to a small level, and the frequency with which the vacuum pump 6 is operated is reduced. As a result, deterioration in fuel efficiency is suppressed. In addition, since residual negative pressure exists in the conduit 21 and the diaphragm chamber, it takes a short time to reach the set negative pressure for throttling the intake throttle valve 2 after the switching valve 11 is turned on, and the intake throttle valve 2 closes. Valve responsiveness is improved. Therefore, vibration can be reliably reduced. Next, FIGS. 3 and 4 show a second embodiment of the present invention. In this embodiment, the pressure switch 1
3 is input directly to the ECU 60 via the conduit 13a, and based on the signal from the ECU 60, the shutoff valve 61 connected to the atmospheric air introduction port 11a of the switching valve 11 is closed. The cutoff valve 61 is provided with an atmospheric air introduction port 61a. In this way, the opening/closing control of the shutoff valve 61 itself only needs to be controlled so that the negative pressure in the negative pressure introduction passage 21 does not fall below the set pressure. Note that 62 and 63 indicate amplifiers within the ECU 60. Other configurations and effects are the first
According to the example. [Effects of the invention] As explained above, when using the intake throttle control device for a diesel engine of the present invention, the operating negative pressure to the actuator for operating the intake throttle valve is always prevented from decreasing to atmospheric pressure, so that the switching Even when the valve is switched, the drop in negative pressure in the entire negative pressure circuit including the vacuum tank can be suppressed to a small level, and the frequency of operation of the vacuum pump can be reduced. Therefore, electrical load can be reduced and fuel efficiency can be improved. In addition, since a certain level of negative pressure can remain in the negative pressure circuit, the response time for opening and closing the intake throttle valve can be shortened, improving the response of the intake throttle and further reducing vibration. This can be done reliably and quickly. Furthermore, although the noise generated when the vacuum pump is operated is large, by reducing the frequency of operation, the noise can be reduced, thereby improving the product value of the entire vehicle, and by reducing the frequency of operation. It is also possible to improve the durability of the vacuum pump itself.

[Brief explanation of the drawing]

FIG. 1 is an equipment system diagram of an intake throttle control device for a diesel engine according to a first embodiment of the present invention;
The figure is a partial block diagram inside the ECU of the device shown in Figure 1.
FIG. 3 is an equipment system diagram of an intake throttle control device for a diesel engine according to a second embodiment of the present invention, FIG. 4 is a partial block diagram inside the ECU of the device shown in FIG.
FIG. 5 is a schematic equipment system diagram of a conventional diesel engine intake throttle control device. DESCRIPTION OF SYMBOLS 1...Engine, 1a...Intake manifold, 2...Intake throttle valve, 5...Diaphragm device as an actuator, 6...Vacuyume pump, 7...Vacuyume tank, 8...Vacuyume switch, 11... ...Switching valve, 11a...Atmospheric introduction port, 12,61...Shutoff valve, 13...Pressure switch as pressure detection means, 50,60...
E.C.U.

Claims (1)

[Scope of utility model registration request] An intake throttle valve is provided in the intake passage of a diesel engine, and an actuator that operates the intake throttle valve in the closing direction when negative pressure is introduced is connected to the intake throttle valve, and a vacuum pump applies negative pressure to the actuator. A negative pressure introduction passage from a vacuum tank in which pressure is accumulated is connected, and a switching valve is provided in the negative pressure introduction passage for switching the introduction pressure to the actuator between the negative pressure on the vacuum pump side and the atmospheric side. In the intake throttle control device for a diesel engine, a pressure detection means capable of detecting the pressure in the passage is provided in a negative pressure introduction passage from the switching valve to the actuator, and the pressure detection means is provided in the atmospheric air introduction port of the switching valve. Based on a signal from the means, a cutoff valve is operated to cut off communication of the switching valve to the atmosphere when the negative pressure in the negative pressure introduction passage from the switching valve to the actuator decreases to a set value below the intake throttle valve opening negative pressure. An air intake throttle control device for a diesel engine, which is characterized by the following: