JP3740913B2 - Internal combustion engine start assist device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a start assist device for an internal combustion engine in which startability is improved by heating intake air to the internal combustion engine.
[0002]
[Prior art]
In an internal combustion engine, when the engine temperature at the time of starting the engine is low, the fuel is difficult to atomize or vaporize and is difficult to ignite, so that the starting stability of the internal combustion engine is reduced. Therefore, conventionally, as shown in Japanese Utility Model Publication No. 2-47256, for example, an electric heater is provided in the intake passage of the internal combustion engine, and the intake air is heated when the internal combustion engine is started to promote the atomization or vaporization of the fuel. An energization control device for a fuel atomization heater for a vehicle has been proposed. In this energization control device, the electric heater is energized during a period in which the cooling water temperature of the internal combustion engine is lower than a predetermined temperature lower than the warm-up completion water temperature.
[0003]
[Problems to be solved by the invention]
However, in the conventional energization control device for a fuel atomizing heater for a vehicle, the electric heater is energized during a period when the coolant temperature is lower than a predetermined temperature. Even when the fuel cannot be injected due to a failure of the apparatus, the electric heater is energized. Therefore, the power consumption is wasted, and the power consumption of the electric heater is large, which is a factor that reduces the life of the battery. Further, when the energization time to the electric heater is increased as described above, a large relay having high durability is required as a heater relay for driving the heater, and such a relay becomes expensive.
[0004]
The present invention has been made in view of such circumstances, and an object of the present invention is to start an internal combustion engine that can reduce wasteful power consumption of an electric heater and can be a small and inexpensive heater relay. It is to provide an auxiliary device.
[0005]
[Means for Solving the Problems]
In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, there is provided an electric heater for heating the intake air to the internal combustion engine, water temperature detecting means for detecting the cooling water temperature of the internal combustion engine, and a period until the cooling water temperature reaches a predetermined heating end temperature. In the start assist device for an internal combustion engine provided with an energization control means for driving the electric heater in the above, the predetermined heating end temperature is set to a lower value as the cooling water temperature at the start of the internal combustion engine is lower. To do.
[0008]
According to the above configuration, when the internal combustion engine is started, the electric heater is driven by the energization control unit for a period of time during which the coolant temperature of the internal combustion engine reaches the predetermined heating end temperature. Since the lower the coolant temperature at the start of the internal combustion engine, the lower the value, the lower the power consumption of the electric heater can be reduced, and the energization time of the heater relay that drives the electric heater is shortened. The heater relay can be small and inexpensive.
[0009]
According to a second aspect of the invention, large in a starting aid for an internal combustion engine according to claim 1, increase the amount of up to the completion of the heating temperature for the cooling water temperature at the start of the internal combustion engine the lower the cooling water temperature at the start The gist is that the value is set.
[0010]
According to the above configuration, when the internal combustion engine is started, the electric heater is driven by the energization control means for a period of time during which the cooling water temperature of the internal combustion engine reaches a predetermined heating end temperature. Since the amount of increase from the water temperature to the heating end temperature is set to a larger value as the cooling water temperature at the start is lower, it is possible to reduce wasteful power consumption in the electric heater, and for the heater that drives the electric heater. The energization time of the relay can be shortened, and the heater relay can be made small and inexpensive.
[0011]
According to a third aspect of the present invention, in the internal combustion engine start assist device according to any one of the first and second aspects, an abnormality detection means for detecting an abnormality of the fuel supply device, and the fuel supply by the abnormality detection means. The gist of the present invention is to include stop means for stopping the driving of the electric heater when an abnormality of the apparatus is detected.
[0012]
According to the above configuration, when the abnormality of the fuel supply device is detected by the abnormality detection means regardless of the coolant temperature of the internal combustion engine, the driving of the electric heater is stopped by the stop means. Therefore, wasteful power consumption in the electric heater can be reduced, the energization time of the heater relay for driving the electric heater can be shortened, and the heater relay can be made small and inexpensive. .
[0013]
According to a fourth aspect of the present invention, there is provided a starting assist device for an internal combustion engine according to the third aspect , wherein the fuel supply device is a fuel injection device that injects fuel based on a control signal.
[0014]
According to the above configuration, since the fuel supply device is a fuel injection device that injects fuel based on the control signal, abnormality of the fuel injection device can be directly detected using a signal from the fuel injection device.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in a diesel engine as an internal combustion engine will be described with reference to the drawings.
[0016]
As shown in FIG. 1, the diesel engine E includes a cylinder head 11 and a cylinder block 13 in which a plurality of cylinders 12 (only one of which is shown in FIG. 1) is formed. A piston 14 is provided in each cylinder 12 so as to be able to reciprocate. A combustion chamber 15 is formed by the piston 14 and the inner wall of the cylinder 12 and the cylinder head 11.
[0017]
Intake air is supplied to the combustion chamber 15 via an intake passage 16, and an intake heater 17 as an electric heater for heating the intake air sucked into the combustion chamber 15 is supplied to the intake passage 16. Is provided. The intake heater 17 is a heater that utilizes the self-temperature control characteristic of a positive characteristic (PTC) thermistor, and has a property that its resistance value increases rapidly when the temperature exceeds a predetermined temperature. It is controlled, and self-temperature control can be performed at a predetermined temperature without red heat like a nichrome wire heater. In the present embodiment, the intake heater 17 is energized and driven by a heater relay 18 controlled by the electronic control unit 30. The heater relay 18 outputs a drive voltage for driving the intake heater 17 based on a control signal from the electronic control unit 30 and outputs an energization confirmation signal to the electronic control unit 30. This energization confirmation signal is a signal based on the current value of the intake heater 17 so that a failure of the intake heater 17 can be detected.
[0018]
The cylinder head 11 is provided with a fuel injection valve 20 that directly injects fuel into the combustion chamber 15 corresponding to each cylinder. An amount of fuel corresponding to the operating state of the engine is pumped to the fuel injection valve 20 at appropriate times from the fuel injection pump 21. The fuel injection pump 21 is provided with a known electromagnetic spill valve 22. The electromagnetic spill valve 22 is, for example, a normally open type electromagnetic valve. The electromagnetic spill valve 22 is energized and driven by a drive circuit 23 controlled by an electronic control unit 30. The drive circuit 23 outputs a drive voltage for driving the electromagnetic spill valve 22 based on a control signal from the electronic control device 30, constitutes an abnormality detection means, and outputs an injection confirmation signal to the electronic control device 30. It has become. The injection confirmation signal is a signal based on the current value of the electromagnetic spill valve 22, and can detect a failure of the electromagnetic spill valve 22. When the electromagnetic spill valve 22 is not energized, the fuel pressure from the fuel injection pump 21 to the fuel injection valve 20 is stopped. On the other hand, when the electromagnetic spill valve 22 is energized, fuel pressure feeding to the fuel injection valve 20 is allowed. That is, the electronic control unit 30 energizes the electromagnetic spill valve 22 to allow the fuel to be pumped to the fuel injection valve 20 before starting the injection by the fuel injection pump 21, and appropriately calculates the fuel injection amount based on the pumping. The fuel injection of the diesel engine E is stopped by stopping energization of the electromagnetic spill valve 22 when the period (time) corresponding to the required injection amount is reached.
[0019]
The diesel engine E is provided with various sensors for detecting the engine operating state. The fuel injection pump 21 is provided with a rotational speed sensor 24 for detecting the engine rotational speed of the diesel engine E. Further, the cylinder block 13 is provided with a water temperature sensor 25 as water temperature detecting means for detecting the temperature of the cooling water of the diesel engine E (cooling water temperature THW).
[0020]
The detection signals output from the sensors 24 and 25, the energization confirmation signal of the heater relay 18, and the injection confirmation signal of the drive circuit 23 are all input to the electronic control device 30. This electronic control device 30 constitutes an energization control means, a stop means, and an abnormality detection means, and controls the fuel injection by driving the electromagnetic spill valve 22 based on these signals, and at the time of starting the engine The energization control of the heater 17 is executed. In addition, the electronic control unit 30 includes a memory 31 that stores and holds a program for executing such fuel injection control and energization control, a calculation map, data calculated when the control is executed, and the like.
[0021]
The electronic control device 30 starts control for starting the diesel engine E when the ignition switch 26 is turned on.
Further, the electronic control unit 30 promotes fuel atomization by executing energization control of the intake heater 17 to heat the intake air. The energization control of the intake heater 17 is executed in a period until reaching the heating end temperature set according to the engine temperature at the start, that is, the cooling water temperature at the start. As shown by the solid line in FIG. 3, the heating end temperature is set to a lower value as the starting water temperature is lower, and the amount of increase to the heating end temperature with respect to the starting water temperature is increased as the starting water temperature is lower. Is set. For example, when the water temperature at start-up is −25 ° C., the heating end temperature is set to 0 ° C., and the amount of increase in water temperature is 25 ° C. In addition, when the water temperature at start-up is 0 ° C., the heating end temperature is set to 20 ° C., and the amount of increase in water temperature is 20 ° C. When the temperature of the combustion chamber 15 rises from the starting water temperature to the heating end temperature with the operation of the engine E, the temperature of the wall surface of the combustion chamber 15 is a temperature at which the injected fuel can be atomized. The heating end temperature can be set in accordance with the water temperature at start-up.
[0022]
Further, when the electronic control unit 30 detects an abnormality of the fuel injection pump 21 based on the injection confirmation signal of the drive circuit 23 or detects a failure of the intake heater 17 based on the energization confirmation signal of the heater relay 18. Regardless of the cooling water temperature, the energization control of the intake heater 17 is stopped. This is because when the diesel engine E is started, if the fuel injection pump 21 is abnormal and fuel is not injected, the diesel engine E cannot be started. In such a case, the intake heater 17 is driven. This is to prevent unnecessary power consumption from increasing.
[0023]
Next, the intake heater OFF control in the diesel engine E configured as described above will be described.
FIG. 2 is a flowchart showing a processing procedure of the intake heater OFF control. This OFF control is executed by the electronic control unit 30 as a time interruption process at predetermined intervals.
[0024]
In this process, first, when the ignition switch 26 is turned on, the energization time of the intake heater 17 is set in the energization control counter, and this energization time is subtracted as time elapses.
[0025]
In step 100, it is determined whether the remaining energization time of the intake heater 17 is zero. If the remaining energization time is 0, the routine proceeds to step 180 where the heater relay 18 is turned off, the energization of the intake heater 17 is stopped, and this routine is terminated. If the remaining energization time is not 0 in step 100, the process proceeds to step 110.
[0026]
In step 110, it is determined whether or not the current cooling water temperature is greater than the warm-up completion determination value (40 ° C. in the present embodiment) indicated by a broken line in FIG. If the cooling water temperature is higher than the warm-up completion determination value, it is not necessary to heat the intake air for atomization of the injected fuel, and the routine proceeds to step 180 where the heater relay 18 is turned off and the intake The energization of the heater 17 is stopped. When the cooling water temperature is equal to or lower than the warm-up completion determination value, the process proceeds to step 120.
[0027]
In step 120, it is determined whether or not the electromagnetic spill valve 22 has failed based on the injection control signal of the drive circuit 23. When the electromagnetic spill valve 22 has failed, the routine proceeds to step 160, and when the electromagnetic spill valve 22 has not failed, the routine proceeds to step 130.
[0028]
In step 160, it is determined whether a starter ON signal is output from the ignition switch 26 or not. Even if the starter ON signal is output and the diesel engine E is cranked by a starter (not shown), since the electromagnetic spill valve 22 is broken, fuel injection cannot be performed and the diesel engine E cannot be started. In step 180, the heater relay 18 is turned off, and the energization of the intake heater 17 is stopped.
[0029]
In step 130, it is determined whether or not the rotational speed NE of the engine E is greater than a predetermined value n0. When the rotational speed NE of the engine E is greater than the predetermined value n0, the routine proceeds to step 170, and when the rotational speed NE is less than the predetermined value n0, the routine proceeds to step 140.
[0030]
In step 170, it is determined whether or not the current cooling water temperature is higher than the heating end temperature corresponding to the starting water temperature of the internal combustion engine. When the current cooling water temperature is higher than the heating end temperature, the routine proceeds to step 180 where the heater relay 18 is turned off and the intake heater 17 is de-energized. If the current cooling water temperature is equal to or lower than the heating end temperature, the process proceeds to step 140.
[0031]
In step 140, it is determined whether or not the current battery voltage is equal to or lower than a predetermined value V0. When the battery voltage is less than or equal to the predetermined value V0, power generation by the alternator becomes difficult, so the routine proceeds to step 180 where the heater relay 18 is turned off and the intake heater 17 is de-energized. If the current battery voltage is greater than the predetermined value V0, the process proceeds to step 150.
[0032]
In step 150, it is determined whether the intake heater 17 has failed based on the energization confirmation signal of the heater relay 18. If the intake heater 17 has failed, the routine proceeds to step 180 where the heater relay 18 is turned off. If the intake heater 17 has not failed, this routine is temporarily terminated.
[0033]
According to the start assist device of the present embodiment that performs the energization control of the intake heater at the time of engine start with the aspect described above, the following effects can be obtained.
In this embodiment, the heating end temperature is set according to the water temperature at the start of the engine E, and the heating end temperature is set to a lower value as the cooling water temperature at the start of the engine E is lower. The amount of increase from the water temperature to the heating end temperature was set to a larger value as the water temperature at the start was lower. Then, the intake heater 17 is driven during a period until the cooling water temperature of the engine E reaches the heating end temperature. Therefore, in this embodiment, it is not necessary to energize the intake heater 17 until the coolant temperature reaches the warm-up completion determination value, and wasteful power consumption at the intake heater 17 can be reduced. Further, the energization time of the heater relay 18 that drives the intake heater 17 can be shortened, and the heater relay 18 can be made small and inexpensive.
[0034]
In the present embodiment, when an abnormality of the fuel injection pump 21 (electromagnetic spill valve 22) is detected at the start of the diesel engine E, the drive of the intake heater 17 is stopped regardless of the cooling water temperature of the diesel engine E. I made it. As described above, when the fuel is not injected due to the abnormality of the fuel injection pump 21, the engine E cannot be started. However, by stopping the drive of the intake heater 17, useless power consumption in the intake heater 17 can be eliminated. In addition, the energization time of the heater relay 18 can be shortened, and the heater relay 18 can be made small and inexpensive.
[0035]
In the present embodiment, when an abnormality of the intake heater 17 is detected when the diesel engine E is started, the drive of the intake heater 17 can be stopped regardless of the cooling water temperature of the diesel engine E, and the heater relay 18 The heater relay 18 can be made small and inexpensive.
[0036]
In the present embodiment, since the fuel supply device is the fuel injection pump 21 (electromagnetic spill valve 22) that injects fuel based on the control signal of the electronic control device 30, it is easy and direct using the signal from the drive circuit 23. In addition, the abnormality of the electromagnetic spill valve 22 can be detected.
[0037]
The embodiment may be changed as follows, and even in that case, the same operation and effect can be obtained.
In the above embodiment, the diesel engine E including the intake heater 17 that heats the intake air in the intake passage 16 as an electric heater is embodied, but the diesel engine including the glow heater that heats the intake air in the combustion chamber 15 is used. It may be embodied.
[0038]
In the above embodiment, the invention is embodied in a diesel engine as an internal combustion engine, but may be embodied in a gasoline engine. When implemented in a gasoline engine, the fuel supply device may be a fuel injection type or a carburetor type.
[0040]
-You may be made to change arbitrarily the process order of steps 120-170 in the said embodiment.
Next, other technical ideas that can be grasped from the above embodiments will be described below.
[0041]
In the internal combustion engine start assist device according to any one of claims 1 to 4 ,
The electric heater is an internal combustion engine start assist device provided in either the intake passage or the combustion chamber of the internal combustion engine.
[0042]
The internal combustion engine start assist device according to claim 4 , wherein the fuel injection device includes a fuel injection pump that discharges high-pressure fuel, a fuel injection valve for in-cylinder injection, a fuel injection pump, and a fuel injection valve. A spill valve that is provided on the communicating supply passage and that releases high-pressure fuel discharged from the fuel injection pump based on a control signal, and the abnormality detection means does not operate the spill valve in response to the control signal A start assist device for an internal combustion engine that detects this.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a diesel engine according to an embodiment.
FIG. 2 is a flowchart showing a processing procedure for intake heater OFF control in the same embodiment;
FIG. 3 is a map showing the relationship between the starting water temperature and the heating end temperature in the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Cylinder head, 12 ... Cylinder, 13 ... Cylinder block, 14 ... Piston, 15 ... Combustion chamber, 16 ... Intake passage, 17 ... Intake heater as an electric heater, 18 ... Heater relay, 21 ... Fuel supply device Fuel injection pump, 22 ... electromagnetic spill valve, 23 ... drive circuit constituting abnormality detection means, 24 ... rotational speed sensor, 25 ... water temperature sensor as water temperature detection means, 26 ... ignition switch, 30 ... energization control means, stop means And an electronic control unit as abnormality detecting means, E ... a diesel engine as an internal combustion engine.

Claims (4)

  An electric heater for heating the intake air to the internal combustion engine;
  Water temperature detecting means for detecting the cooling water temperature of the internal combustion engine;
  Energization control means for driving the electric heater in a period until the cooling water temperature reaches a predetermined heating end temperature;
In an internal combustion engine start assist device comprising:
  An internal combustion engine start assist device in which the predetermined heating end temperature is set to a lower value as the cooling water temperature at the start of the internal combustion engine is lower.   The start assist device for an internal combustion engine according to claim 1,
  An internal combustion engine start assist device in which the amount of increase from the cooling water temperature at the start of the internal combustion engine to the heating end temperature is set to a larger value as the cooling water temperature at the start is lower.   The internal combustion engine start assist device according to any one of claims 1 and 2,
  Furthermore, an abnormality detection means for detecting an abnormality of the fuel supply device,
  Stop means for stopping the drive of the electric heater when the abnormality of the fuel supply device is detected by the abnormality detection means;
A start assist device for an internal combustion engine comprising:   The internal combustion engine start assist device according to claim 3,
  The fuel supply device is an internal combustion engine start assist device that is a fuel injection device that injects fuel based on a control signal.

Images