JPH0562208B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air intake device that increases the temperature of intake air through adiabatic compression in order to promote starting of a diesel engine and improve its emission.

(Prior art) Conventionally, as shown in Japanese Utility Model Application Publication No. 59-107936, in order to improve ignitability during starting time in a diesel engine, the intake air supplied to the combustion chamber is adiabatically compressed to increase the intake air temperature. An intake device (starting promotion device) is known. This device is
The intake passage is equipped with an on-off valve that opens during the intake stroke. Specifically, an intake throttle valve is provided in the main intake passage, and an on-off valve is provided in the bypass intake passage that bypasses this intake throttle valve. During low-load operation until warm-up, the main intake passage is throttled by the intake throttle valve, and the on-off valve is opened in the middle of the intake stroke using a valve operating mechanism or a pressure-responsive on-off valve. ing. The operation of the on-off valve restricts the intake air into the combustion chamber until the middle of the intake stroke, and rapidly introduces the intake air into the combustion chamber from the middle of the intake stroke to perform adiabatic compression. According to this device, compared to the case where intake air is heated by an air heater, a large amount of energy is not consumed as electric power, and moreover, the intake air temperature can be efficiently raised in the combustion chamber.
In addition, in the above-mentioned conventional device, the on-off valve is operated during startup and warm-up operation, but if the on-off valve is operated during normal operation, for example in the relatively low rotation and low load operating range, the intake air temperature can be reduced. The rise improves combustibility and prevents the generation of white smoke, HC, etc.

By the way, when operating the on-off valve in a specific operating range like this, it is not possible to simply operate the on-off valve in a preset operating range. During a transition period when the operating state shifts from to the operating range, when the on-off valve is operated, the combustibility increases and the engine speed increases, which may cause hunting of the on-off valve and make the operating state unstable. Ta.

(Object of the Invention) In view of these circumstances, the present invention aims to improve combustibility and emission by adiabatic compression of intake air by operating the on-off valve in operating ranges where misfires and poor combustion are likely to occur. The present invention provides an intake device for a diesel engine that can stabilize the operating state by preventing hunting of an on-off valve when the valve moves from a non-operating region to an operating region.

(Structure of the Invention) The present invention provides an on-off valve in the intake passage, closes the on-off valve until the middle of the intake stroke to restrict the introduction of intake air into the combustion chamber, and opens the on-off valve during the intake stroke. In a diesel engine intake system that rapidly introduces intake air into the combustion chamber to perform adiabatic compression, the on-off valve is activated and the operation function of the on-off valve is stopped so that the intake passage is closed throughout the intake stroke. A drive means that switches between an inoperative state and an open state for a period of time, and a relatively low rotation speed,
A setting means for setting the operating range of the on-off valve on the low load side, and the on-off valve is operated in the operating range set by the setting means, and in the non-operating range on the higher rotation and high load side, the above-mentioned operation is stopped. and a control means for controlling the driving means so as to operate the on-off valve after a predetermined period of time when transitioning from the non-operating region to the operating region.

In other words, after the operating state shifts from the non-operating region to the operating region, until the operating state changes to a certain extent and hunting no longer occurs in the on-off valve.
It is designed to maintain the state in which the working function of the on-off valve is stopped.

(Embodiment) FIGS. 1 and 2 show a first embodiment of the present invention. In these figures, 1 is a cylinder of a diesel engine, and a combustion chamber 3 is formed above a piston 2 inside the cylinder.
An intake port 5 equipped with an intake valve 4 and an exhaust port (not shown) equipped with an exhaust valve are open to the intake port 5 . The intake passage 6 of each cylinder, which communicates with the intake port 5, is provided with an on-off valve 10 that restricts the introduction of intake air into the combustion chamber 3 until the middle of the intake stroke, and then rapidly directs intake air into the combustion chamber 3 from the middle of the intake stroke. An intake air introduction regulating device is provided that introduces air into the engine 3 and performs adiabatic compression. In this embodiment, this intake air introduction regulating device is composed of an automatic valve type on-off valve 10 that responds to pressure changes. It is designed to automatically open when the negative pressure in the passage 6 exceeds a predetermined value. Further, this on-off valve 10 is rotatably attached to the intake passage 6 via the rotating shaft 10a, so that it can be positioned in the intake passage 6 as described above and in the recess 7 provided on the side wall of the intake passage 6. It is possible to switch between the states stored in the

The specific structure of the on-off valve 10 will be explained with reference to FIG. 2. This on-off valve 10 has a valve body 13 provided in a valve chamber 11 and abutting against a valve seat 12 from the upstream side.
A diaphragm 15 is connected to the valve body 13 via a connecting shaft 14, two chambers 16 and 17 are partitioned by the diaphragm 15, and a valve is provided in one of the chambers 16 to open the valve body 13. It is provided with a return spring 18 that biases toward the valve.
The one chamber 16 has a valve body 13 and a connecting shaft 14.
and communicates with the intake passage 6 downstream of the valve body 13 via a communication hole 19 penetrating the diaphragm 15,
The other chamber 17 communicates with the upstream side of the intake passage 6 and is maintained at approximately atmospheric pressure. According to this structure, by setting the pressure receiving area of the diaphragm 15 and the valve body 13 appropriately and keeping the spring force of the return spring 18 relatively small, the intake passage 6
In the state where the valve body 13 is located within the combustion chamber 3, the valve body 13 is opened during the intake stroke when the negative pressure generated in the combustion chamber 3 and the downstream side of the intake passage 6 communicating therewith exceeds a predetermined value, and then the negative pressure becomes sufficiently small. At this point, the valve body 13 is closed.

The rotating shaft 10a of the on-off valve 10 is connected to an actuator 21. This actuator 2
1 is formed by, for example, a diaphragm device, and is connected to a vacuum pump 23 via a passage 22, and into the passage 22 there are two states: one for introducing negative pressure from the vacuum pump 23 into the actuator 21, and the other for introducing atmospheric air. A switching valve 24 is provided for switching to. These actuator 21, passage 22,
The vacuum pump 23 and the switching valve 24 constitute a driving means for switching the on-off valve 10 between an operating state and an inactive state. In other words, when atmospheric pressure is introduced into the actuator 21, the on-off valve 10 is switched to the intake passage 6. When the vacuum pump 23 introduces negative pressure into the actuator 21, the on-off valve 10 is rotated to the retracted position and the intake passage 6 is opened to the inactive state. There is.

Reference numeral 25 denotes a control circuit for controlling the driving means, which is composed of a microcomputer, etc., and receives signals for detecting the operating state from the rotational speed detecting means 26 and load detecting means 27, etc., installed in the fuel injection pump, etc. , outputs a control signal to the switching valve 24. This control circuit 25 constitutes a setting means for setting the operating range of the on-off valve 10 and a control means for controlling the driving means, and the operating range of the on-off valve 10 is set to a relatively low rotation and low load side. is stored in the memory in this control circuit 25, and the on-off valve 10 is operated in this operating region, and the above-mentioned operation is stopped in the non-operating region, and when a transition from the non-operating region to the operating region is made, a predetermined period of time has elapsed. The driving means is controlled so that the on-off valve 10 is operated later.

Control of the drive means by this control circuit 25 is later performed as shown in FIG. In other words, the operating status (engine speed, load) as shown by the solid line
When transitions from the non-operating region to the operating region, the on-off valve 10 is closed for a certain period of time T set on the timer.
The switching from OFF (stopped) to ON (activated) is delayed. Further, when the operating state shifts from the operating region to the non-operating region as shown by the broken line, the on-off valve 10 is immediately switched from ON to OFF.

FIG. 4 shows a flowchart of the control operation by such a control circuit 25. In this figure, in step _SA1 , it is checked whether the on-off valve 10 is in operation. If the on-off valve 10 is in operation, it is checked in steps SA ₂ and SA ₃ whether or not the operating state has entered the non-operating region based on the detection of the engine speed and load, and if it is not in the non-operating region, it is checked. The above detection is repeated with the on-off valve 10 in the operating state, and when it is in the non-operating region, step SA ₄ is performed.
The operation of the on-off valve 10 is stopped, that is, the on-off valve 1
actuator 2 to rotate 0 to the storage position.
Control 1.

When the operation is stopped in this way, after returning, the determination progress at step _SA1 becomes NO, and the process moves to steps _SA5 and subsequent steps. step
SA ₅ and SA ₆ check whether the operating state is in the operating range based on the detection of the engine speed and load, and repeat the detection if it is not in the operating range. When the operating area is reached, step SA ₇ ,
After a certain delay time has elapsed by operating the timer from the start of counting to the end of counting in SA ₈ , the operating state is still in the operating state based on the detection of engine speed and load in steps SA ₉ and SA ₁₀ . If the judgment result is YES, the on-off valve ₁₀ is opened in step SA11.
In other words, the actuator 21 is controlled to position the on-off valve 10 in the intake passage 6. It should be noted that if the operation falls into the non-operating region during the above-mentioned delay, the process returns from step _SA10 to step _SA5 .

According to the above-mentioned intake system, when the on-off valve 10 is in the operating state located in the intake passage 6, the on-off valve 10 opens in the middle of the intake stroke, that is, until the middle of the intake stroke, the on-off valve 10 is closed to the combustion chamber 3. The intake air intake is restricted and the negative pressure inside the combustion chamber 3 gradually increases.
When this negative pressure exceeds a predetermined value, the on-off valve 10 is opened, and a large amount of intake air is suddenly introduced into the fuel chamber 3 from the auxiliary intake passage 6b. As a result, the intake air is adiabatically compressed, and the temperature inside the combustion chamber 3 increases. The on-off valve 10 is operated as described above in the relatively low-speed, low-load operating region, which is a region where misfires and poor combustion are likely to occur, and the intake air temperature is increased, thereby improving ignition performance. and increased flammability. On the other hand, misfires and poor combustion are inherently less likely to occur in the non-operating region at high speeds and high loads, and if the on-off valve 10 is operated in such a region, there is a possibility of insufficient intake air. 10 is stopped and the intake passage 6 is opened, thereby preventing the generation of black smoke due to insufficient intake air.

Furthermore, especially when transitioning from the non-operating region to the operating region, the operation of the on-off valve 10 is delayed for a certain period of time, so hunting of the on-off valve 10 is prevented.
In other words, the on-off valve 10 immediately moves to the operating region.
When the operation starts, the combustibility improves and the operating state shifts to the non-operating region, causing hunting in which the on-off valve 10 repeatedly operates and stops. After the delay time has elapsed, the engine speed and load have become low to a certain extent, so even if the on-off valve 10 starts operating, the operating state will not deviate to the non-operating region, and hunting will be prevented. . Immediately after this transition, the engine temperature has already risen, so even if the start of operation of the on-off valve 10 is delayed, no misfire or the like will occur. Note that when transitioning from the operating region to the non-operating region, if the start of operation of the on-off valve 10 is delayed, a lack of intake air may occur during that time and black smoke may be generated. It is now possible to switch.

The drive means is controlled by the control circuit 25 in the fifth
It may also be done as shown in FIG. That is, in this example, as shown in FIG. 5, within the operating area A of the on-off valve, the switching area B from the inactive state to the operating state of the on-off valve 10 is narrower than this area.
is set. When the operating state changes in the direction of arrow A from the operating region A to the non-operating region C, the on-off valve 10 is switched from the operating state to the non-operating state at the boundary point a between the two regions A and C. When the operating state changes in the opposite direction of arrow B, the on-off valve 10 is switched from the inactive state to the operating state at point b when the switching region B is reached.

This control will be explained using the flowchart of FIG. 6. First, in step _SB1 , it is checked whether the on-off valve 10 is in operation. And if it is working, step
SB ₂ , step SB ₃ checks whether the operating state has left the operating range A based on the detection of the engine speed and load, and when it has exited the operating range A, steps SB ₄
The on-off valve 10 is brought into a non-operational state. In addition, if the on-off valve 10 is in a non-operating state in step SB ₁ , it is checked in step SB ₅ and step SB ₆ whether or not it has entered the switching region B based on the detection of the engine speed and load, and the switching is performed. When entering region B, the on-off valve 10 is operated in step _SB7 .

Even with this control, the operating state is in the non-operating region C.
When it moves from the operating area A to the operating area A,
The on-off valve 10 is operated after a predetermined period of time required from reaching the switching region B to reaching the switching region B, thereby preventing hunting.

FIG. 7 shows another embodiment of the invention. In this embodiment, the intake passage 6 for each cylinder 1 is composed of a main intake passage 6a and a sub-intake passage 6b, and the main intake passage 6a is provided with an intake throttle valve 30, and the sub-intake passage 6b is provided downstream of the main intake passage 6a. The downstream end is open,
An automatic valve type opening/closing valve 10 that responds to pressure changes is provided in the auxiliary intake passage 6b, thus forming an intake air introduction regulating device. Further, a driving means is constituted by an actuator 31 that opens and closes the intake throttle valve 30, a passage 32 for operating the actuator, a vacuum pump 33, and a switching valve 34. With this structure, when the main intake passage 6a is throttled by the intake throttle valve 30, the on-off valve 10 automatically operates to open in the middle of the intake stroke, and when the intake throttle valve 30 is opened, the main intake passage 6a is Intake air is freely introduced into the combustion chamber 3, and the operation of the on-off valve 10 is stopped. Therefore, the on-off valve 10 is connected to the sub-intake passage 6b.
It can be fixedly placed.

In this case as well, the control circuit 25 controls the intake throttle valve 30 via the drive means to perform control as shown in FIGS. 3 and 4, or as shown in FIGS. 5 and 6. All you need to do is to perform appropriate control.

FIG. 8 shows yet another embodiment of the invention. In this embodiment, an automatic valve type on-off valve 10
Instead, a rotary valve type opening/closing valve 40 that opens and closes in the middle of the intake stroke in conjunction with an engine rotating shaft (not shown) is provided in the auxiliary intake passage 6b, and the other structure is the same as that shown in FIG. It is the same as the example. Also in this structure, when the intake throttle valve 30 provided in the main intake passage 6a is opened, intake air is freely introduced from the main intake passage 6a into the combustion chamber 3,
By lifting the restriction on intake air introduction, the operating function of the on-off valve 40 is substantially stopped. Therefore, the control circuit 25 may be configured to control the opening and closing of the intake throttle valve 30 via the driving means as in the embodiment shown in FIG.

As yet another embodiment, the intake passage configuration is similar to that of the embodiment shown in FIGS. 1 and 2, but instead of the automatic valve type on-off valve 10, a rotary valve that opens the intake stroke midway in conjunction with the engine output shaft is used. A valve-type on-off valve may be provided in the main intake passage. In this case, by incorporating into the interlocking mechanism an interlocking shutoff means that can stop the on-off valve in the open state, or an on-off timing variable means that can change the opening and closing timing so that the on-off valve is open during the entire intake stroke. , it is possible to substantially stop the operating function of the on-off valve, and such means may be controlled by a control circuit.

(Effects of the Invention) As described above, the present invention provides an on-off valve that opens in the middle of the intake stroke in the intake passage so that the intake air temperature can be increased by adiabatic compression of the intake air. The operating range of the on-off valve is set to the rotation and low load side, and the on-off valve is activated after a predetermined period of time when the operating state shifts from the non-operating area to the operating area. It is possible to prevent poor combustion, white smoke, HC, etc. on the side, and black smoke on the high-speed, high-load side, while also preventing hunting of the on-off valve when transitioning to the above operating state. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of an on-off valve, and FIG. 3 is an explanatory diagram showing an example of control of an on-off valve in response to changes in operating conditions.
Fig. 4 is a flowchart of this control, Fig. 5 is an explanatory diagram showing another example of control of the on-off valve, Fig. 6 is a flowchart of this control, and Fig. 7 is another embodiment of the device of the present invention. FIG. 8 is a sectional view showing still another embodiment. 1... Cylinder, 3... Combustion chamber, 4... Intake valve, 6... Intake passage, 10, 40... Open/close valve, 3
0...Intake throttle valve, 21-24, 31-34...
Drive means, 25...control circuit.

Claims (1)

[Claims] 1. An on-off valve is provided in the intake passage, and the on-off valve is closed until the middle of the intake stroke to restrict the introduction of intake air into the combustion chamber, and by opening the on-off valve during the intake stroke, the intake air is suddenly forced into the combustion chamber. In the intake system of a diesel engine which is introduced to perform adiabatic compression, there are two states: a state in which the on-off valve is operated, and an inoperative state in which the operating function of the on-off valve is stopped and the intake passage is opened for the entire intake stroke period. a setting means for setting the operating range of the on-off valve to relatively low rotation and low load, and a setting means for operating the on-off valve in the operating range set by the setting means to operate at higher rotation and higher load. A control means is provided for controlling the drive means so that the operation is stopped in the non-operation area on the side, and the opening/closing valve is operated after a predetermined period of time when the area is shifted from the non-operation area to the operation area. A distinctive feature of the diesel engine intake system.