JPH0828321A - Warming-up control device for diesel engine - Google Patents

Abstract

PURPOSE:To increase an engine output while keeping an idling engine speed constant. CONSTITUTION:A diesel engine has a common rail 14 and a control valve 10 of a fuel injection pressure P. Also provided are an engine speed sensor 5, an accelerator sensor 3, a cooling water temperature sensor 6 and a pressure sensor 7. When a cooling water temperature T is not higher than a preset value T at the time of idling operation, an injection nozzle 11 and the fuel injection pressure P are so controlled that a set fuel pressure P higher than a normal value is obtained and a set idling engine speed N is kept.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine warm-up operation control device, and more particularly, to a diesel engine warm-up operation control capable of preventing a decrease in cooling water temperature when heating is performed during idling. It relates to the device.

[0002]

2. Description of the Related Art It is well known that a diesel engine has a warm-up promoting function for promoting a rise in engine temperature. For example, when the idling control means disclosed in Japanese Patent Laid-Open No. 4-66742 is detected to be in an idling state, the injection pulse width is adjusted to adjust the fuel pressure so that the set idling rotation speed is achieved. When the low temperature startability is important, the fuel pressure is kept as high as possible and the pressure is kept constant, and the injection pulse width is changed by changing the injection end time or the injection start time. That is recommended.

Further, in order to stabilize the idling rotation speed, the means disclosed in Japanese Patent Laid-Open No. 63-71542 sets a predetermined dead zone in the target idling rotation speed and averages the detected engine rotation speed. If the engine speed is within the dead zone, the fuel injection amount is not changed. By the way, in an internal combustion engine installed in an automobile, cooling water is used as a heat source for heating the interior of the vehicle, but when heating is performed while idling for a long time in the cold season, the cooling water temperature decreases and heating efficiency decreases. In some cases, electronic control has been conventionally performed to increase the fuel injection amount, advance the injection timing, and increase the engine rotation speed. However, when the engine rotation speed is increased and the cooling water temperature is increased in this way, there is a problem that the operating noise of the engine is increased and the noise is deteriorated.

[0004]

SUMMARY OF THE INVENTION According to the present invention, the fuel pressure can be arbitrarily set without being restricted by the operating conditions of the common rail (accumulator) attached to the diesel engine. When the fuel pressure is increased, the load of the high pressure pump increases. It is possible to increase the engine output while maintaining the idling speed, increase the engine output without increasing the engine operating noise, and raise the cooling water temperature during idling operation. It is intended to provide an operation control device.

[0005]

In order to achieve the above object, the structure of a diesel engine warm-up operation control device of the present invention is a common rail fuel pressure control means provided between a high pressure pump and a fuel injection nozzle. And a diesel engine equipped with fuel injection control means for controlling the fuel injection timing and the injection period of the fuel injection nozzle, an idling detection means for detecting an idling operation state of the engine is attached, and the engine is in an idling operation state, and When the cooling water temperature is equal to or lower than the set temperature, the set fuel pressure in the common rail is increased, the fuel injection timing and the injection period are adjusted, and a control device for maintaining the set idling rotation speed is provided.

The fuel pressure control means for the common rail is not particularly limited, but for example, a relief valve for adjusting the discharge pressure of the high pressure pump can be used. Also, the fuel injection control means is not particularly limited, but a leak valve of a fuel injection nozzle can be used. The means for switching the normal operation mode of the diesel engine to the control mode (hereinafter referred to as warm-up mode) operation may be started when the heating switch is turned on, for example, and the cooling water temperature during idling operation is equal to or lower than the set value. In this case, the control device may be formed in advance so as to switch to the warm-up mode control.

Although the idling state detecting means is not particularly limited, for example, a rotation speed sensor and an accelerator sensor are provided to detect that the engine rotation speed is below a certain rotation speed and the accelerator opening is below a certain opening. It can be a means to do. The means for controlling the fuel injection timing and the fuel injection period to keep the idling rotation speed constant is a conventional means, that is, an electromagnetic three-way switching valve (leak valve) for lifting the needle valve of the fuel injection nozzle. ) Switching timing with the engine rotation speed, the top dead center of the piston, the accelerator opening, etc. as parameters, and preferably by controlling the injection nozzle by three operation control of proportional, differential and integral (PID). it can. In determining the control condition at that time, for example, a control map may be stored in advance in a storage device of the control device, and a set value may be read by an output signal from each sensor. A calculation formula is stored and calculation is performed each time. You may do it.

[0008]

[Function] The fuel injection system of the diesel engine is provided with a common rail and a high-pressure pump, and the means for controlling the fuel injection pressure by increasing the fuel injection pressure without changing the idling speed increases the engine friction by the high-pressure pump to increase the set fuel pressure of the common rail. By doing so, the heat generation of the engine can be increased and the temperature of the cooling water can be raised. Therefore, it is possible to increase the temperature of the cooling water when the engine is started in an extremely low temperature condition or when the vehicle interior is heated for a long time during idling operation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the accompanying drawings with reference to the accompanying drawings. As shown in FIG. 1, the control system of the control device 1 of the present embodiment includes an accelerator sensor 3 for detecting a depression angle of an accelerator 2 of a diesel engine (not shown), and a top dead center of a piston (not shown) of the engine. A high-pressure fuel pump by inputting detection signals from a sensor 4, a rotation sensor 5 for detecting the rotation speed of the engine, a water temperature sensor 6 for detecting the cooling water temperature, a pressure sensor 7 for detecting the fuel injection pressure, and a heating switch 8. The electromagnetic leak valve 12 including the electromagnetic relief valve 10 of 9 and the three-way valve of the fuel injection nozzle 11 is controlled.

Further, the control device 1 may be an electronic control means such as a normal microcomputer, may be formed exclusively for the main control, or may be a common control device for other controls such as various controls during normal operation. You may use. The high-pressure pump 9 uses a piston 9c that reciprocates by a cam 9b attached to a drive shaft 9a to increase the pressure of fuel sent from the fuel pump 13 to a high pressure, and a common rail 14 via a check valve 9d.
The electromagnetic relief valve 10 is attached to a bypass passage 9g for returning the high pressure side passage 9e to the low pressure side passage 9f. Reference numeral 15 shown in FIG. 1 is a fuel tank.

The common rail 14 is of a normal specification in which a part of the fuel passage 16 is enlarged to make a vacant chamber, and its internal pressure (fuel pressure) P is detected by the pressure sensor 7. The fuel injection nozzle 11 is a conventional one that lifts the needle valve 11b by the electromagnetic leak valve 12 and injects the fuel sent to the fuel reservoir 11a through the fuel passage 17 from the injection hole 11c into the combustion chamber (not shown). It was used. Reference numeral 17 shown in FIG. 1 is a fuel leak passage, and the fuel tank 15 is the same as the suction side fuel tank 15 of the fuel pump 9.

Next, the operation of the control device 1 of the first embodiment will be described with reference to the flow chart shown in FIG. When the warm-up mode control is started by turning on the heating switch 8 or the like, it is determined in step 1 whether the engine rotation speed N is lower than the set rotation speed N ₀ (for example, normal idle rotation speed + α rpm, α is, for example, 50 to 100 rpm). If it is determined that a negative result is obtained, step 1 is executed again, and if a positive result is obtained, at step 2, whether or not the accelerator opening V is less than the set accelerator opening V ₀ (for example, 5%). If it is determined that a negative result is obtained, step 1 is executed again, and if a positive result is obtained, in step 3, the cooling water temperature T is set to the set cooling water temperature T ₀ (for example, 50 to 60 ° C.).
It is determined whether or not the value is less than a suitable value of the range), and if a negative result is obtained, step 1 is executed again, and if a positive result is obtained, step 4 is executed.

In step 4, it is first determined whether or not the elapsed time τ is zero, and if it is zero, counting of the elapsed time since the execution of step 4 is started, and the elapsed time τ is set to the set elapsed time τ. It is determined whether or not it is ₀ (for example, an appropriate value in the range of 2 to 3 minutes), and if a negative result is obtained, step 1 is executed again, and if a positive result is obtained, the above elapsed time is set. Returning to zero, in step 5, the injected fuel pressure, that is, the set pressure P ₀ in the common rail 14
And the set injection timing t ₀ are read from the map previously input to the control device 1, and the set injection period θ ₀ by the PID operation
Is calculated by the following formula.

[0014] Note that k _1, k _2, k ₃ , and k ₄ are constants, respectively, and d / d
θ represents a derivative with respect to time. Then, the control device 1 counts time based on the output signal of the top dead center sensor 4 based on the newly set set injection period θ ₀ , and when the set injection timing t ₀ is reached, the set injection period θ is set. _{During 0,} a signal for switching the electromagnetic leak valve 12 to lift the needle valve 11b is output. While the signal is being output, the fuel pressure overcomes the elastic force of the return spring 11d to inject the fuel for a predetermined time. Then, the program returns to the start and step 1 is executed again.

In step 4, the control operation is provided with a hysteresis so that the control does not become an excessive control, and it is not essential to the present invention, and if necessary, any control can be performed as long as the excessive control can be prevented. Means can be used. Next, the engine speed N-fuel injection amount Q of the present embodiment
(NQ) characteristics will be described. In FIG. 3, the curve a
Shows an NQ curve when the accelerator opening is 100%, a curve b shows an NQ curve when the accelerator opening is 0%, a curve c shows an NQ curve in the warm-up mode, and d The curve shows an NQ curve under no load, that is, an engine load curve, and the e curve shows an engine load curve during a warm-up mode.

At the time of idling in the normal mode, at a coordinate position of point A (injection amount Q ₀ , engine speed N ₀ ) where the curve b at 0% accelerator opening and the engine load curve d at no load intersect. Operate. When the warm-up mode is entered, the pressure of the common rail is increased, the work of the high-pressure pump 9 is increased, the load of the engine is increased, and the d-curve shifts to the e-curve, but as described above, the engine rotation speed N is N _0. Therefore, the b curve moves to the position where the e curve intersects with the B point (that is, the c curve). That is, the injection amount Q can be increased from Q _{0 to} Q _B while the rotational speed N remains the set value N ₀ .

When only the engine load is increased (that is, the fuel pressure P is increased) without performing the PID control for maintaining the rotation speed N at N ₀ , the engine load curve changes from the d curve to the e curve. , N-Q curve remains b curve,
The engine output Q _T and the rotation speed N are determined at point C, the rotation speed N decreases to N _0-n , and the rotation becomes unstable. Further, if the conventional general engine is idled up, that is, only the injection amount is increased without increasing the engine load, the engine load curve remains the d line and the NQ curve shifts from the b curve to the c curve. , The engine output is at the intersection (point D) of both curves, the rotational speed N increases to N _{0 + n} , and noise increases.

As described above, the first embodiment has explained the control operation when the warm-up mode control is selected, for example, heating is performed during the idling operation. However, the cooling water temperature T is kept constant during the idling operation in the normal operation control mode. When the temperature decreases, the control device automatically switches to the warm-up mode control, and a flowchart can be formed so that each set value is changed to the warm-up mode. In this case, in order to stabilize the rotation in the state where the set idling rotation speed is slightly increased and the engine friction is increased, the set values of the necessary control elements such as the idling rotation speed and the fuel pressure are automatically changed. The control device can be set in advance.

[0019]

As described above, the warm-up operation control device for the diesel engine of the present invention is provided with the common rail for keeping the fuel injection pressure constant, and the cooling water temperature is equal to or lower than the predetermined value during the idling operation. Since the fuel pressure of the common rail is increased to increase the load of the high pressure pump,
The engine output can be increased by increasing the engine friction while maintaining the idling rotation speed.
Therefore, the effect of facilitating the rise of the cooling water temperature during the warm-up operation at the time of starting at a very low temperature and preventing the cooling water temperature from decreasing during the idling operation while heating for a long time can be achieved. can get.

[Brief description of drawings]

FIG. 1 is a control system diagram of a warm-up operation control device for a diesel engine according to an embodiment of the present invention.

FIG. 2 is a flow chart for explaining a control operation of the control device shown in FIG.

FIG. 3 is a graph showing engine speed-engine output characteristics for explaining the operation of the control operation shown in FIG.

[Explanation of symbols]

1 Control Device 3 Accelerator Sensor 4 Top Dead Center Sensor 5 Rotation Sensor 6 Water Temperature Sensor 7 Pressure Sensor 8 Heating Switch 9 High Pressure Pump 10 Electromagnetic Relief Valve (Control Valve) 11 Fuel Injection Nozzle 12 Electromagnetic Leak Valve 13 Fuel Pump 14 Common Rail N Engine rotation speed N ₀ Set rotation speed P Fuel pressure t ₀ Set injection timing θ ₀ Set injection engine V ₀ Set accelerator opening

Claims (3)

[Claims] 1. A diesel engine comprising a common rail fuel pressure control means provided between a high-pressure pump and a material injection nozzle, and a fuel injection control means for controlling a fuel injection timing and an injection period of the fuel injection nozzle, When the idling detection means for detecting the idling operation state of the engine is attached and the engine is in the idling operation state and the cooling water temperature is equal to or lower than the set temperature, the set fuel pressure in the common rail is increased and the fuel injection timing and A warm-up control device for a diesel engine equipped with a control device that adjusts the injection period and maintains a set idling rotation speed. 2. The fuel pressure control means for the common rail comprises:
The warm-up operation control device for a diesel engine according to claim 1, which is a relief valve for adjusting a discharge pressure of the high-pressure pump. 3. The warm-up operation control device for a diesel engine according to claim 1, wherein the fuel injection control means is a leak valve of a fuel injection nozzle including a three-way switching valve.