JPH06294327A - White smoke reducing method and device for diesel engine with supercharger - Google Patents

Abstract

PURPOSE:To reduce exhaust of white smoke by shutting off a bypass passage by a signal which detects the low load condition of engine output and detection of cold condition of an engine, putting a supercharger in the full load condition and performing warming up operation of the engine rapidly. CONSTITUTION:The injection condition of fuel is detected by a no-load sensor switch at a moving position of a control rack 24 of an injection pump 18, and the cold condition of an engine 22 is detected by a cooling water temperature sensor switch 46. When both of these sensor switches are being turned on, it is the cold start condition. In this condition, as a valve open driving circuit 54 of a bypass valve 16 is shut off, a bypass passage 14 is forcedly shut off even if bypass air charging from another system is attempted to save fuel, a supercharger 10 is in the full load condition, and drive output increases. Consequently, the warming up operation is carried out rapidly, and exhaust of white smoke ends in a short period of time. Thus, it is possible to reduce the exhaust of white smoke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for reducing white smoke emitted from a diesel engine equipped with a supercharger.

[0002]

2. Description of the Related Art In a diesel engine, a supercharger is provided for the purpose of improving output so as to secure a necessary air amount at full load. However, since the positive displacement supercharger is a mechanical drive type driven by an engine or the like, it significantly deteriorates fuel efficiency when no load is applied. That is, the supercharger provided in the intake passage is rotationally driven by the power transmission means such as a belt driven by the engine. For this reason, a diesel engine having such a supercharger structure drives the supercharger even in a no-load state where supercharging is not required, and supplies excess air to the engine, resulting in an excessive amount of air. I will work. Therefore, the engine-driven supercharger has a drawback that the fuel efficiency is deteriorated.

In order to reduce such deterioration of fuel efficiency under no load, a bypass passage bypassing the turbocharger is provided in the intake passage, and a bypass valve capable of opening and closing this passage is attached so that the supercharger is under no load. It is suggested not to. This is provided with a supercharger in the main intake passage and a bypass passage that bypasses the front and rear of the supercharger. An opening / closing valve capable of opening and closing the passage is provided in the bypass passage. The opening / closing operation of this bypass valve is performed by the opening / closing mechanism that works in conjunction with the control lever of the fuel injection pump driven by the engine, so that the bypass passage is opened to prevent supercharging when there is no load. I try to avoid doing different jobs.

[0004]

However, in the conventional structure in which the bypass passage with the built-in bypass valve is used to bypass air supply to the supercharger, the bypass passage is opened in a no-load state when the engine is started. The following problems occurred. That is, in the diesel engine, since the periphery of the combustion chamber is cooled immediately after the low temperature start, the fuel is included in the exhaust gas in the unburned state and is discharged. The exhaust gas in the unburned state becomes white smoke emission, which may continue for about 5 to 10 minutes until the engine is warmed up. This white smoke emission not only brings down the appearance of the product image, but also has a great effect on the work environment such as bleeding in the eyes and odor, especially when using a forklift equipped with this type of engine for indoor work. It's a problem.

The present invention pays attention to the above-mentioned conventional problems, and in particular, it is possible to rapidly shift the unburned fuel state at the time of engine start up to a complete combustion state, thereby eliminating white smoke emission as quickly as possible. An object of the present invention is to provide a white smoke reduction method and device for a diesel engine with a supercharger.

[0006]

In order to achieve the above object, a method for reducing white smoke in a diesel engine with a supercharger according to the present invention is to install the supercharger in the intake passage of the diesel engine and A method for reducing white smoke in a diesel engine in which a bypass path is provided and a valve is provided in the bypass path, in which the bypass path is shut off by a detection signal of a low load state of an engine output and a detection signal of an engine cooling state. With the turbocharger at full load, the engine is rapidly warmed up to reduce white smoke emissions.

Further, the white smoke reducing device for a diesel engine with a supercharger according to the present invention has a supercharger attached to an intake passage of a diesel engine and a bypass passage of the supercharger provided with a valve provided in the bypass passage. A device for reducing white smoke in a mounted diesel engine, comprising means for detecting a low load state of engine output and means for detecting an engine cold state, and the bypass valve driven by an AND signal from these detecting means. The valve opening drive circuit is provided with a cutoff switch circuit. In this case, the engine output low load detection means may be constituted by a sensor switch for detecting a decrease in the injection amount of the fuel injection pump of the fuel injection pump, and the engine cold state detection means may be constituted by a cooling water temperature sensor switch. Good. Then, these may be connected in series, and a cutoff relay switch that is actuated by the closed circuit drive may be interposed in the valve opening drive circuit of the bypass valve.

[0008]

According to the above construction, the fuel injection state is detected at the moving position of, for example, the control rack of the injection pump, and the cold state of the engine is detected by the cooling water temperature sensor switch. It is confirmed that both of these sensor switches are in the ON state because the engine is not in the warm-up state and the fuel injection amount is low, and therefore the engine is in the low load operation state. This state is the cold start state.In this state, the valve opening drive circuit of the bypass valve is cut off, so even if you try to supply bypass air from another system to reduce fuel consumption, the bypass path is forcibly cut off. , The supercharger becomes full load and the drive output increases. As a result, the warm-up operation is rapidly performed, and the white smoke discharge is completed in a short time. When the temperature of the cooling water rises due to warming up, the cutoff switch circuit inserted in the valve opening drive circuit becomes inoperative, and the bypass valve opening drive circuit is normally controlled.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of a method and apparatus for reducing white smoke in a diesel engine with a supercharger according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory view of a white smoke reducing device for a diesel engine with a supercharger according to an embodiment. As shown in this figure, the supercharger 10 is provided in the main intake passage 12, and the bypass passage 14 that bypasses the front and rear of the supercharger 10 is provided. Open a passage in this bypass passage 14,
An on-off valve 16 that can be shut off is provided. Also,
A fuel injection pump 18 for supplying fuel is used for the diesel engine 2 via a power transmission mechanism 20 such as a gear device.
2 can be driven. The fuel injection pump 18 includes a control rack 24 that controls the fuel injection amount.
However, it is provided so as to project from a well-known pump case, and moves forward and backward with respect to the pump case by a governor (not shown) to adjust the fuel injection amount. Further, a rack sensor 26 for detecting the no-load position (idle position) of the control rack 24 is attached to the pump case. The rack sensor 26 operates the switch circuit 28 by detecting the unloaded position.

As shown in FIG. 2, the rack sensor 26 has a bottomed cylindrical case 30, and the fuel injection pump 18 is provided with the front end of the control rack 24 inserted into the opening side of the case 30. It is screwed on. Further, a stopper 32 made of a ring-shaped insulating material is provided so as to project at a central portion in the longitudinal direction inside the case 30, and an electrode 34 is fixed to the case bottom side of the stopper 32,
The spring seat 36 that contacts the electrode 34 is locked. A spring 38 is interposed between the bottom of the case 30 and the spring seat 36 to urge the spring seat 36 toward the stopper 32. In addition, an electrode 40 is arranged on the bottom of the case 30 at a portion in contact with the spring 38, and the spring 38 is grounded via the electrode 40.

The electrode 34 provided on the stopper 32 is connected to one terminal of the relay coil 42 of the relay switch which constitutes the switch circuit 28. The other end of the relay coil 42 is connected to the power supply 44, and when the spring seat 36 contacts the electrode 34, the relay coil 42 is excited to close the switch circuit 28.

A cooling water temperature detection switch circuit 46 is provided which is connected in series with the no-load detection switch circuit 28 and operates when the engine cooling water temperature is low. As shown in FIG. 1, this is configured by a bimetal switch that operates by the temperature of the cooling water flowing through the radiator 48 attached to the engine 22, and the bimetal 50 contacts the contact point when the temperature of the cooling water is in a predetermined high temperature state. 52
It makes contact with and closes the circuit. As a result, the no-load detection switch circuit 28 and the cooling water temperature detection switch circuit 46 form an AND circuit in series.

On the other hand, the bypass valve 16 provided in the bypass passage 14 is opened and closed by an electromagnetically operated valve operating device 54. The valve operating device 54 is
A solenoid 56 connected to a power source 44 that is shared with the operating power source of the no-load detection switch circuit 28 and the cooling water temperature detection switch circuit 46, a drive rod 58 that advances and retreats by the solenoid 56, and connects the drive rod 58 and the bypass valve 16. The operating member 60 and a return spring (not shown) are included. The valve operating device 54 constitutes a valve opening drive circuit, and the bypass valve 16 opens the flow path by energization from the power source 44, so that the air bypassing the supercharger 10 is sucked into the engine 22. A circuit cutoff switch 62 is provided in the middle of such a valve opening drive circuit. This constitutes a normally-closed switch by a relay switch, so that the power supply circuit from the power source 44 to the valve operating device 54 is normally closed.
The relay coil 64 of the circuit breaking switch 62 is connected to the series circuit of the no-load detection switch circuit 28 and the cooling water temperature detection switch circuit 46, and the opening / closing contact 66 is connected to the power supply circuit to the valve operating device 54.

The operation of the white smoke reducing device of the diesel engine with a supercharger configured as described above is as follows. When the engine 22 is in an unloaded state, the fuel injection pump 18
The control rack 24 has a small amount of protrusion from the pump casing, and its tip is not in contact with the spring seat 36 of the rack sensor 26, as shown in FIG. For this reason,
The spring seat 36 is pressed against the electrode 34 provided on the stopper 32 by the spring 38, and electrically connects the electrode 34 and the electrode 40 via the spring seat 36 and the spring 38. Therefore, the switch circuit 28 is turned on by the current flowing through the relay coil 42. On the other hand, the cooling water temperature detection switch circuit 46 connected in series with this detects the cooling water temperature,
When the temperature is high, the bimetal 50 comes into contact with the contact 52 and turns on to close the circuit. When both of these switch circuits 28 and 46 are turned on, the solenoid 64 of the circuit breaker switch 62 connected to the power supply circuit to the valve operating device 54 is connected to the power source 44 to be excited and the valve operating device 54 is connected. Cut off the power supply. As a result, the valve operating device 40 operates in the bypass valve 1
Open 6 to prevent supercharging and avoid the supercharger doing extra work. Close the valve when the temperature is low. As a result, the supercharger 10 is in the full load state, and the engine 22 is all supercharged. Therefore, the engine 2
The driving horsepower of No. 2 becomes large, and the driving horsepower of 7 to 8 times is generated as compared with the case where the bypass 14 is opened. Therefore, when the engine 22 is in the cooling state and the engine 22 is in the no-load state from the fuel supply state, that is, immediately after the engine 22 is started, the work amount of the engine 22 is maximized and the engine is rapidly warmed up. Of.

ON / OFF states of the no-load detection switch circuit 28 and the cooling water temperature detection switch circuit 46,
FIG. 3 shows the operating state of the circuit breaker switch 62 resulting from this. In this figure (2), the no-load detection switch circuit 2
8 indicates A, the cooling water temperature detection switch circuit 46 indicates B, and the circuit cutoff switch 62 indicates C. In the characteristic diagram of the engine output and the engine rotation speed ((1) in the figure), the switch circuits 28 and 46 are in the high load state.
Neither of them is in the ON state (positions 1, 2, 3), and in the low load state (positions 5, 6), the circuit breaker switch 62 is not turned on and the bypass 16 is closed only when the engine is cold. . As a result, when the engine is started, the supercharger 10 performs its maximum work and rapidly shifts to the warm-up state, and as a result, the white smoke discharge time due to unburned fuel can be significantly shortened.

FIG. 4 shows the relationship between white smoke emission and changes in the driving horsepower of the engine 22. This figure is the change in white smoke disappearance time with increasing engine load, and it can be seen that the increase in load significantly reduces the white smoke disappearance time. Therefore, as in the above-described embodiment, the engine start start state is grasped by detecting the load and the temperature of the cooling water, and in such a case, the full output is applied to the supercharger 10 to increase the drive output, so that the white smoke disappears. It turns out that the time can be shortened.

In the above embodiment, the no-load detection switch circuit and the cooling water temperature detection switch circuit are connected in series to form an AND circuit, but this is digitally processed by the binarized signal. It is also possible.

[0019]

As described above, according to the present invention,
The bypass signal is cut off by the detection signal of the low load state of the engine output and the detection signal of the cold state of the engine to make the supercharger full load state to rapidly warm up the engine. Since the state detection means and the engine cold state detection means are provided, and configured to be realized by a cut-off switch circuit that is driven by an AND signal from these detection means and is interposed in the valve opening drive circuit of the bypass valve, , In particular, the state immediately after the engine is started can be surely detected, and at this time the bypass path is cut off so as to give the full load to the supercharger, so even if an attempt is made to bypass air supply from another system to reduce fuel consumption, Drive output increases. As a result, warm-up operation is performed rapidly,
An excellent effect is obtained that the white smoke discharge can be completed in a short time.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a white smoke reduction device for a diesel engine with a supercharger according to an embodiment.

FIG. 2 is a configuration diagram before and after an operating state of a no-load detection switch circuit of the same device.

FIG. 3 is an explanatory diagram of a switch on / off state of the device.

FIG. 4 is a relationship diagram between engine load and white smoke disappearance time.

[Explanation of symbols]

 10 supercharger 12 main intake passage 14 bypass passage 16 bypass valve 18 fuel injection pump 20 power transmission mechanism 22 engine 24 control rack 26 rack sensor 28 no-load detection switch circuit 30 case 32 stopper 34 electrode 36 spring seat 38 spring 40 electrode 42 Relay coil 44 Power supply 46 Cooling water temperature detection switch circuit 48 Radiator 50 Bimetal 52 Contact 54 Valve operating device 56 Solenoid 58 Drive rod 60 Operating member 62 Circuit break switch 64 Relay coil 66 Open / close contact

Claims (5)

[Claims] 1. A method for reducing white smoke in a diesel engine, wherein a turbocharger is attached to an intake passage of a diesel engine, a bypass passage of the supercharger is provided, and a valve is provided in the bypass passage. The low-load state detection signal and the engine cold state detection signal are used to cut off the bypass passage to bring the turbocharger into a full-load state and rapidly warm up the engine to reduce white smoke emission. White smoke reduction method for diesel engine with supercharger. 2. A white smoke reducing device for a diesel engine, comprising a turbocharger attached to an intake passage of a diesel engine, a bypass passage of the supercharger provided, and a valve interposed in the bypass passage, the engine output comprising: And a means for detecting the engine cold state are provided, and a cutoff switch circuit is provided which is driven by an AND signal from these detection means and is interposed in the valve opening drive circuit of the bypass valve. A white smoke reduction device for diesel engines with a supercharger. 3. The white smoke reducing device for a diesel engine with a supercharger according to claim 2, wherein the engine output low load detecting means is a sensor switch for detecting a decrease in the injection amount of the fuel injection pump. . 4. A cooling water temperature sensor switch is used as the means for detecting the engine cold state.
White smoke reduction device for diesel engine with supercharger described in. 5. A white smoke reducing device for a diesel engine, comprising: attaching a supercharger to an intake passage of a diesel engine, providing a bypass passage of the supercharger, and providing a valve in the bypass passage. Sensor switch for detecting the low load state of the fuel injection pump from the decrease in the injection amount of the fuel injection pump and a cooling water temperature sensor switch for detecting the engine cold state are connected in series and driven by these ON signals to open the bypass valve. A white smoke reduction device for a diesel engine with a supercharger, characterized in that a cutoff switch circuit provided in a drive circuit is provided.