JPH0816473B2 - Vehicular air conditioning diesel engine glow plug preheat control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a preheating control method for a glow plug of a diesel engine for vehicle air conditioning.

(Prior Art) A large-sized vehicle such as a bus is equipped with a main engine consisting of a diesel engine and a sub-engine, as shown in JP-A-58-22713, and the main engine is mainly used for traveling. The sub engine is used for air conditioning.

Both of the air conditioners have a cooling cycle and a warming cycle. In the air conditioning casing, there is a blower,
An evaporator for a cooling cycle and a heater core for a warming cycle are arranged. The compressor arranged outside the air conditioning casing and connected to the evaporator and the blower are driven by the sub engine. Further, the air conditioner has control means for air conditioning. In this control means, the air conditioning mode is determined based on at least the set temperature, the outside air temperature, and the temperature in the passenger compartment, the sub engine is operated in the cooling mode and the dehumidifying mode, and the sub engine is operated in the heating mode and the air blowing mode. It has been stopped.

By the way, in the diesel engine used for the main engine and the sub engine, if the temperature in the cylinder is low, the engine cannot be started.Therefore, the glow plug installed in the cylinder is preheated before starting the engine. Fuel ignition is ensured and starting performance is ensured.

Normally, the preheating time of the glow plug is set by a timer and is constant, and in order to secure the startability, it is set assuming the worst condition, that is, the case where the cylinder temperature is the lowest. However, if the outside air temperature is high, or if the engine is warm because it has only been running for a short period of time, the preheating may be longer than necessary even though the cylinder temperature is high. Becomes
There was a waste of power and a waste of time waiting for operation to start.

The drawbacks of the method of determining the preheating time by the timer as described above become remarkable especially when the sub engine is started. This is because the sub-engine frequently repeats shutting down and starting every time the air conditioning mode is switched, and when starting after a temporary shutdown, the engine is warm and the glow plug preheat time is short. This is because the preheating is performed for a longer time than necessary in spite of all the above, and the waste of electric power and waste of waiting time described above are repeated many times.

In order to eliminate the above-mentioned inconvenience, Japanese Utility Model Laid-Open Publication No. 54-68038 discloses a preheating control for a glow plug based on an engine cooling water temperature and an outside air temperature by a preheating control means different from the air conditioning control means. Are in control. That is, the higher the outside air temperature and the higher the engine cooling water temperature, the shorter the preheating time of the glow plug is controlled.

Japanese Patent Publication No. 60-53798 also discloses a control method for determining the preheating time of the glow plug based on the temperature of the engine cooling water.

(Problems to be Solved by the Invention) In Japanese Utility Model Application Laid-Open No. 54-68038 and Japanese Patent Publication No. 60-53798, there is no description that the preheating control method for the glow plug is applied to a sub engine for air conditioning. However, it is especially suitable for sub-engines that frequently stop and start. However, since the temperature of the cooling water of the engine is used as important information, a relatively high-precision temperature sensor for detecting the temperature of the cooling water must be prepared, which has a drawback of increasing the cost.

(Means for Solving Problems) The present invention has been made to solve the above problems, and the gist thereof is that, when the outside air temperature is lower than the reference temperature, the outside air temperature sensor and the room A diesel engine for vehicle air-conditioning, characterized in that the preheating control of the glow plug is performed based on the temperature data from the temperature sensor, and the preheating time is shortened as the difference between the outside air temperature and the room temperature increases or the outside air temperature increases. It is in the glow plug preheating control method.

(Function) It is necessary in the cooling mode and the dehumidifying mode to drive the compressor by operating the diesel engine for air conditioning. When the dehumidifying mode is executed when the outside air temperature is lower than the reference temperature, the indoor temperature becomes higher than the outside air temperature. Therefore, the difference between the indoor temperature and the outside air temperature means that the engine is running to execute the dehumidification mode, or the dehumidification mode has been stopped and a short time has not yet elapsed. To do. Therefore, the temperature difference can be used as an index of whether or not the engine is warm, instead of the conventional engine coolant temperature.

The present invention is based on the above principle. When the outside air temperature is lower than the reference temperature, the larger the difference between the outside air temperature and the indoor temperature and the higher the outside air temperature, the shorter the preheating time of the glow plug. By controlling in this way, the preheating time can be optimized.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings from FIG. 1 to FIG. FIG. 3 shows a schematic configuration of the air conditioner 1 used for the bus. The air conditioner 1 has an air conditioning casing 1a. An outside air introducing duct 2 and an indoor air introducing duct 3 are connected to one end of the air conditioning casing 1a. A switching door 4 is rotatably arranged in the vicinity of the connecting portion so that either outside air or room air can be selectively introduced. In addition to the air-conditioning casing 1a, a ceiling-side air outlet duct 5 and a floor-side air outlet duct 6 are connected, and a switching door 7 is rotatably arranged in the vicinity of the connecting portion. Either of the blowouts can be selected.

The air conditioner 1 has a blower 10 arranged in the air conditioning casing 1a. By the rotation of the blower 10, air is sent from the introduction ducts 2, 3 through the air conditioning casing 1a to the blowout ducts 5, 6. The drive shaft 10a of the blower 10 is connected to the output shaft 12a of the blower motor 12 via the pulley 11 with an electromagnetic clutch.
It is connected to.

The air conditioner 1 further has a warming cycle 20 and a cooling cycle 30.

The warm-up cycle 20 has heater cores 21a and 21b arranged apart from each other in the air conditioning casing 1a, and the heater cores 21a and 21b are connected to a main engine 23, which is a diesel engine for traveling, via a pipe 22. There is. The pipe 22 is provided with a heater 24, a pump 25, and a hot water valve 26. Then, the high-temperature water after cooling the main engine 23 is heated by the heater 24 and becomes even higher in temperature.
The heat is exchanged with air passing through the air conditioning casing 1a while being supplied to the heaters 21a and 21b and circulating in the heater cores 21a and 21b, thereby warming the air. The water after the heat exchange is returned to the main engine 23 through the pipe 22.

Mix doors 27a and 27b are provided near the heater cores 21a and 21b.
Are rotatably arranged, and the heater core of the air that has passed through an evaporator 31 to be described later depends on the angle.
The ratio of those that pass 21a and 21b and those that do not pass is determined, and the final temperature of air supply is determined.

The cooling cycle 30 has an evaporator 31 arranged in the air conditioning casing 1a. This evaporator 31
Via the pipe 32, it is connected to the compressors 33a and 33b, the condenser 34, the liquid tank 35, and the expansion valve 36 arranged outside the air conditioning casing 1a. The cooling medium stored in the liquid tank 35 is sent to the evaporator 31 in a gas-liquid mixed state by the expansion valve 36, and in the process of circulating the evaporator 31, deprives the heat of evaporation from the air passing through the air conditioning casing 1a and removes it. Cool the air. The evaporated cooling medium is compressed by the compressors 33a and 33b, liquefied by the condenser 34, and returned to the liquid tank 35.

The compressors 33a, 33b are driven by a sub engine 40 which is a diesel engine dedicated to air conditioning. More specifically, the output shaft 40a of the sub-engine 40 has three pulleys 41a, 41b, 42 with electromagnetic clutches.
Is attached to this pulley with electromagnetic clutch 41a,
41b is connected to each compressor 33a, 33b via endless belts 43a, 43b and pulleys 44a, 44b.

Further, the sub-engine 40 is connected to the drive shaft 10a of the blower 10 via the pulley 42 with an electromagnetic clutch, the endless belt 45, and the pulley 11 with an electromagnetic clutch described above.

A glow plug 49 is installed in each cylinder (not shown) of the sub engine 40.

The air conditioner 1 further has a control unit 50 (control means) shown in FIG. The control unit 50 includes a microcomputer 51, necessary interfaces, an A / D converter and the like (not shown). The control unit 50 includes a set temperature signal from the temperature setter 52, an indoor temperature signal from the indoor temperature sensor 53, an outdoor air temperature signal from the outdoor air temperature sensor 54, a solar radiation intensity signal from the solar radiation sensor 55, and a dehumidifying command dry switch. On from 56,
An off signal is input. In the control unit 50,
Based on these signals, one of the heating mode, blower mode, cooling mode, and dehumidification mode is selected, and the blower motor 12, the pulleys 11 and 41 are used to execute the selected mode.
The electromagnetic clutches 57 of a, 41b and 42, the switching actuators 4 and 7 and the actuators 58 of the mix doors 27a and 27b, the heater 24, the pump 25, and the hot water valve 26 are controlled. Since these general controls are known, detailed description will be omitted. In FIG. 4, the electromagnetic clutch 57,
Regarding the door actuator 58, a plurality of door actuators 58 are collectively shown to simplify the drawing.

The sub-engine 40 is stopped in the heating mode and the blowing mode, and is operated only in the cooling mode and the dehumidifying mode. In the operating state of the sub-engine 40,
When the electromagnetic clutch 57 of the pulleys 11, 41a, 41b is turned on, the power of the sub engine 40 is transmitted to the compressors 33a, 33b of the cooling cycle 30, and the electromagnetic clutter 57 of the pulley 11 operates to drive the pulley 11. By connecting the shaft 10a, the power of the sub engine 40 is transmitted to the blower 10.

In the dehumidifying mode, the air introduced from the indoor air introducing duct 3 is cooled by the evaporator 31, and at this time, moisture in the air is condensed and removed from the air. This condensed water is discharged from a drain pipe (not shown). Then, the air from which the moisture is removed is warmed by the heater cores 21a and 21b when it is determined by the mix doors 27a and 27b, and finally the blowing temperature is determined. Normally, with the temperature setter 52, 20
Since -30 ° C is set, in the dehumidification mode when the outside air temperature is 20 ° C or less, the room temperature becomes equal to or higher than the outside air temperature, and heating is substantially performed. Therefore, this 20 ° C. is used as a reference temperature Tr described later. When the outside air temperature exceeds 20 ° C, the room temperature becomes higher or lower than the outside air temperature depending on the set temperature.

In the case of the cooling mode, the proportion of the cold air that has passed through the evaporator 31 being warmed by the heater cores 21a and 21b is small,
For example, it is zero in the case of strong cooling.

The sub-engine 40 is started at the time of starting the air conditioning from the beginning to the cooling and dehumidifying modes, and when shifting from the air blowing and heating modes to the cooling and dehumidifying modes. On this occasion,
Under the control of the control unit 50, the glow plug 49 is first energized to preheat it. After this, starter 59
When (Fig. 4) is started, since the glow plug 49 is in a high temperature state, the ignition of the fuel is ready and the start of the sub engine 40 is secured.

The preheating time of the glow plug 49 is calculated by the microcomputer 51 based on the outside air temperature Ta and the room temperature Tb. More specifically, first, the total temperature information value T for determining the preheating time is obtained as follows.

(A) When the outside air temperature Ta is below the reference temperature Tr = 20 ° C.,
The total temperature information value T is determined by the following equation based on the outside air temperature Ta and the indoor temperature Tb.

T = α (Tb−Ta) + Ta (1) where α is a constant smaller than 1.

The sub-engine 40 is driven when the outside air temperature Ta is 20 ° C. or lower only in the dehumidifying mode, not the cooling mode.
Since the heating is substantially performed as described above, the larger the difference (Tb-Ta) between the indoor temperature Tb and the outside air temperature Ta, the sub engine 40 stops after executing the dehumidification mode and only a short time elapses. Not meant that the sub-engine 40 is still warm. Therefore, the temperature difference (Tb-Ta) is a factor that can replace the temperature of the engine cooling water in the conventional technique.

(B) When the outside air temperature Ta exceeds the reference temperature Tr = 20 ° C., the outside air temperature Ta alone is determined by the following equation.

T = Ta (2) As described above, when the outside air temperature Ta is higher than the reference temperature Tr, it is unclear which of the indoor temperature Tb and the outside air temperature Ta becomes higher. Therefore, the temperature difference is used as the control factor. However, the control is based only on the outside air temperature Ta. However, as will be described later, when the outside air temperature Ta is relatively high, the preheating time becomes relatively short, and the importance of the information as to whether or not the sub-engine 40 is warm becomes weaker. Therefore, even control based only on the outside air temperature Ta is possible. That's enough.

The microcomputer 51 calculates the preheating time from the total temperature information value T obtained by the above equations (1) and (2) based on FIG. That is, the higher the total temperature information value T, the shorter the preheating time. When the outside air temperature is 20 ° C. or less, the preheating time is shortened as the outside air temperature increases and the difference between the outside air temperature and the room temperature increases. When the outside air temperature exceeds 20 ° C, the higher the outside air temperature, the shorter the preheating time.

When switching from the cooling / dehumidifying mode to the air blowing / heating mode, the control unit 50 sends a stop control signal to the actuator (not shown) of the intake shutter to close the intake shutter and close the sub engine 40.
To stop.

The blower motor 10 is driven in the heating mode and the blowing mode. At this time, the output shaft 12a of the blower motor 12 and the drive shaft 10a of the blower 10 are operated by the operation of the electromagnetic clutch 57 of the pulley 11.
The blower motor 12 serves as a power source instead of the sub-engine 40 to rotate the blower 10 in order to bring the blower 10 into the connected state.

Next, the program processing in the microcomputer 51 will be described with reference to FIGS. First, the second
The air conditioning control program in the figure will be briefly described. Data is input from the temperature setter 52, the indoor temperature sensor 53, the outdoor air temperature sensor 54, and the solar radiation sensor 55 with the switch 100, and in the next step 101, the total temperature information value T for mode determination is based on these input data. ′ Is calculated.

In the next step 102, the dehumidifying command dry switch 56
To determine whether or not is on. Next step if off
Is the overall temperature information value T 'at 103, it determines whether the first set value T ₁ by high. If it is higher, it is determined that the cooling mode should be executed, and in step 104, the start control of the sub engine 40 is performed. General temperature information value T 'is in the case of the first set value T ₁ or less, as should perform the air blowing mode or heating mode, the stop control of the sub-engine 40 at step 105.

In step 102, if it is determined that the dry switch 56 is turned on, overall temperature information value T 'it is determined whether higher than the second set value T ₂ at step 106. Note that T ₂ <T ₁ . The total temperature information value T ′ is the second set value T ₂
If the temperature is higher, it is determined that the dehumidification mode or the cooling mode should be executed, and the sub engine 40 is determined in step 104.
Start control of the sub engine 4 at 105 if low
0 stop control is performed. In this case, the dehumidifying mode is set when the total temperature information T ′ is in the range of T _{2 to} T ₁ , and the cooling mode is set when T ₁ or more. By the way, in the range of T from T _{2 to} T ₁ ,
When the dry switch 56 is off, the air blower or the weak heating mode is set.

As described above, when it is determined that the cooling mode or the dehumidifying mode should be executed, and the start control of the sub engine 40 is executed in step 104, the rotation speed of the sub engine 40 is controlled in the next step 107. For example, when it is necessary to strongly cool the air on the basis of the total temperature information value T ',
The rotation speed of the sub-engine 40 is increased, and the rotation speed of the sub-engine 40 is decreased when cooling is performed weakly. Further, in the next step 108, the number of compressors 33a, 33b to be connected to the sub engine 40 is controlled.
One unit for low air conditioning.

Further, when the heating mode or the air blowing mode should be executed, when the sub engine stop control is performed in step 105, the blower motor 12 is driven in step 109 to rotate the blower 10 instead of the sub engine 40 to blow air. To do.

Further, in order to execute the mode corresponding to the total temperature information T ', switching control of the inlet and the outlet is performed in step 110,
The hot water valve 26 and pump 25 are controlled in step 111, the heater 24 is controlled in step 112, and the mix is performed in step 113.
Controls 27a and 27b.

Next, the start control of the sub-engine 40 in step 104 including the characteristic part of the present invention will be described in detail with reference to FIG. First, in step 200, sub engine 4
Determine if 0 is running. If it is in operation, the rotation speed of the sub-engine 40 is immediately controlled in step 107 described above without performing the start control. It should be noted that this determination is made based on, for example, a rotation detection signal from a rotation detection device (not shown) of the sub engine 40.

If it is determined in step 200 that the sub-engine 40 is not operating, the outside air temperature is set to the reference temperature of 20 ° C in step 201.
Judgment is made. If the total temperature information value T is exceeded, the above equation (2) is executed in step 202.
Is set to a value equal to the outside air temperature. When the temperature is 20 ° C. or lower, in step 203, the total temperature information value T is calculated based on the above equation (1).

In the next step 204, the preheating time is calculated from the total temperature information value T.

In the next step 205, it is determined whether or not the number of starts is less than 4. If it is four times, the start failure of the sub-engine 40 is displayed and the sub-engine 40 is stopped at step 206.

If the number of starts is less than four, in step 207, the actuator of the governor is controlled so that the rotation speed of the sub-engine 40 becomes 950 rpm, that is, the rotation speed becomes low, and the intake is performed. Open the shutter.

In the next loop of steps 208-211, the glow plug 49 is preheated for the time determined in step 104 above. That is, in step 208, it is determined whether or not the measurement time of the timer 1 has become equal to or longer than the determined preheating time. If the determined preheating time has not elapsed, the preheating of the glow plug 49 is started or continued in step 209. In the next step 210, it is determined whether or not the timer 1 has started. If it has, step 208
Return to If not started, step 211
After starting timer 1 with, the process returns to step 208.

When the glow plug 49 is preheated for the determined time,
When this is determined in step 208, the process proceeds to step 220, and preheating of the glow plug 49 is stopped.

In the next loop of steps 221-225, the sub-engine 40
The starter 59 is operated for a maximum of 5 seconds until the engine starts. That is, the starter 59 is started in step 221. In step 222, it is determined whether the timer 2 has passed 5 seconds. If 5 seconds have not passed, step
At 223, it is determined whether or not the timer 2 has started. If it has, it is determined at next step 225 whether or not the sub engine 40 has started. If the timer 2 has not started, the timer 2 is started in step 224, and then step 225 is executed.

When it is determined in step 225 that the sub-engine 40 has started, the starter 59 is stopped in step 226. If the sub-engine 40 has not started yet, the process returns to step 221.

If the sub-engine 40 does not start even after 5 seconds, this is judged in step 222, and the next step 227
Then, the starter 59 is once stopped, the number of times of starting is counted, and the process returns to step 205. In this way, the starter 59 is tried up to four times.

As described above, the sub engine 40 starts and steps
After stopping the starter 59 at 226, low speed operation is performed for 2 seconds, for example. That is, in step 230, it is determined whether or not the measurement time of the timer 3 has become 2 seconds or more, and if it is less than 2 seconds, in the next step 231, it is determined whether or not the timer 3 has started, and it has started. If step 230
If not started, the timer 3 is started in step 232 and then the process returns to step 230. When the measured time of the timer 3 becomes 2 seconds or more, the routine proceeds to step 107, where the rotation speed control of the sub engine 40 is executed. After accustoming the drive system to the low speed operation as described above, the high speed operation is performed if necessary.

In the above embodiment, the control means for controlling the switching between heating, cooling and dehumidifying modes also serves as the control means for preheating the glow plug, but these control means may be provided separately.

Further, the main engine together with the sub engine may be incorporated in the cooling cycle.

The line indicating the relationship between the total temperature information value and the preheating time is not limited to the straight line in FIG. 5, and may be stepwise or curved.

When the outside air temperature is higher than the reference temperature, the preheating time may be constant or zero.

The reference temperature to be compared with the outside air temperature may be variable, for example, equal to the set temperature from the temperature setting machine.

(Effects of the Invention) As described above, in the present invention, the glow plug preheating time of the air-conditioning diesel engine can be optimally controlled based on the outside air temperature and the indoor temperature, whereby the startability of the diesel engine can be secured. It is possible to eliminate waste of electric power. Moreover, since the outside air temperature sensor and the room temperature sensor that are used for normal air conditioning control can be used, it is not necessary to prepare a large number of expensive sensors for special preheating control, and the cost can be reduced. it can.

[Brief description of drawings]

The drawings from FIG. 1 to FIG. 5 show an embodiment of the present invention, FIG. 1 is a flow chart showing a detailed program of start control by a microcomputer of an air conditioner, and FIG. 2 is an air conditioning program. FIG. 3 is a schematic diagram showing the entire air conditioner, FIG. 4 is a block diagram showing the input / output of the control unit, and FIG. 5 is a relation between the total temperature information value and the preheating time of the glow plug. FIG. 1 ... Air conditioner, 1a ... Air conditioning casing, 10 ... Blower, 10 ... Warm-up cycle, 21a, 21b ... Heater core, 30
…… Cooling cycle, 31 …… Evaporator, 33a, 33b ……
Compressor, 40 ... Sub engine (diesel engine for air conditioning), 49 ... Glow plug, 50 ... Control device (control unit), 53 ... Indoor temperature sensor, 54
...... Outside air temperature sensor.

Claims (2)

[Claims] 1. An air conditioner in which a blower, an evaporator, and a heater core are arranged in an air conditioning casing for heating, cooling, and dehumidifying a vehicle, and a compressor connected to the evaporator is driven by a diesel engine. Before, the glow plug arranged in the cylinder of the diesel engine is a method of preheating by the control of the control means, in the control means, when the outside air temperature is lower than the reference temperature, the outside air temperature sensor and the indoor temperature Glow plug preheating control is performed based on the temperature data from the sensor, and the preheating time is shortened as the difference between the outside air temperature and room temperature increases or the outside air temperature increases. Plug preheating control method. 2. The control means calculates the total temperature information value T as follows, and controls so as to shorten the preheating time of the glow plug as the total temperature information value T increases. A glow plug preheating control method for a diesel engine for vehicle air conditioning according to claim 1. When Ta ≦ Tr T = α (Tb−Ta) + Ta where Tr is the reference temperature, Ta is the outside air temperature, Tb is the indoor temperature,
α is a constant.