JPH0451743B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas leak detection device for a combustion type heater for a vehicle.

(Prior Art) In order to rapidly start a cold engine, a rapid start device has been developed in which intake air is heated by a rapid heater and then supplied to the engine. This quick start device uses part of the oxygen contained in the intake air drawn into the engine to combust fuel in the rapid heater, and uses the generated heat to raise the temperature of the intake air. This device is used only when starting the engine, so after starting, the heat generated from the rapid heater is used to heat the vehicle's interior. That is, a heat exchanger is disposed between the rapid heater and the intake port of the engine, the heat in the heated intake air is extracted by the heat exchanger, and this heat is used to warm the air sent into the room. It is. Such a system is disclosed, for example, in Japanese Patent Application No. 59-106869.

(Problem to be solved by the invention) By the way, gas leakage from the heat exchanger in such a system also supplies combustion gas containing carbon monoxide (CO) into the vehicle interior, causing artificial damage. This is very dangerous and can cause this.

As a measure to prevent such risks, for example, it is possible to install a CO gas sensor in the indoor air passageway that passes through the heat exchanger to detect gas leaks, but it is recommended to increase the sensitivity of the CO gas sensor for safety reasons. If even a small amount of CO gas enters the air, the entire system may malfunction.
In other words, vehicles often drive in areas with inherently poor air conditions, such as when driving on roads congested with traffic. For example, if exhaust gas from another vehicle is temporarily taken in as heating air, the system may suddenly This may cause a malfunction that causes the machine to stop working.

Furthermore, even if there is no gas leak, it is still dangerous to use the heat-exchanged air as heating air if it is heated to an abnormally high temperature.

An object of the present invention is to provide a gas leak detection device for a vehicle combustion heater that detects gas leaks and abnormal heating.

(Means for Solving the Problems) In order to achieve the object of the invention as described above, the present invention provides a first and a second tube on the air inflow side and the air outflow side, respectively, of a heat exchanger connected to a combustion type heater. A carbon oxide detector is provided, and a means for comparing the outputs of the two carbon monoxide detectors is provided, and the output of the second carbon monoxide detector is higher than the output value of the first one by a predetermined value. Provided is a gas leak detection device for a combustion type heater for a vehicle, which includes means for stopping the operation of the combustion type heater when the combustion type heater stops operating.

(Operation) If combustion gas leaks from the heat exchanger into the heating air stream when the rapid combustion heater is in operation, a carbon monoxide detector provided downstream of the heat exchanger detects this. As a result, a difference occurs between the output of the carbon monoxide detector installed upstream of the heat exchanger and the output of the carbon monoxide detector installed downstream, and when that value reaches a predetermined value or more, the heat exchanger will quickly fail. Accidents are prevented by stopping the operation of combustion heaters and preventing harmful air from entering the company. Further, when carbon monoxide temporarily enters the heating air into the heat exchanger from the outside, the outputs of the two carbon monoxide detectors become equal. Therefore, there is no difference in output between the two, and there is no possibility that the operation of the rapid combustion type heater will be suddenly stopped.

(Example) Fig. 1 is a sectional view showing the gas leak detection device of the present invention, Figs. 2 and 3 are system configuration diagrams thereof, and Figs. 3 is a control flowchart of the illustrated embodiment.

In the drawings, reference numeral 1 denotes a combustor, in which fuel supplied by driving a fuel pump 8 is vaporized by a glow plug heater 11, mixed with combustion air, and combusted. Combustion gas from the combustor 1 is supplied to an engine (not shown) through a heat exchanger 2. 3
is a blower, which is configured to guide the air taken in to the heat exchanger 2, and to discharge the air warmed by the heat exchanger 2 into the vehicle interior. Here, the heat exchanger 2 is provided with a temperature sensor 4, and an atmospheric carbon monoxide gas sensor 5 is provided in the duct between the blower 3 and the heat exchanger 2. A carbon monoxide gas sensor 6 for heated air is provided in the duct from 2 to the vehicle interior.

7 is a switching door actuator, and the switching door 1 switches heated air into or outside the vehicle interior.
0 is switched under the control of the controller 9. Note that the pump 8 described above also has a controller 9.
is driven by the control of

Next, the operation of the gas leak detection device of the present invention will be explained.

When the rapid combustion heater is operating, combustion air is taken into the combustor 1, mixed with fuel vaporized by the glow plug heater 11, and combusted within the combustor 1. Combustion gas is supplied to the engine through a heat exchanger 2. On the other hand, air taken in by the blower 3 is heated by the heat exchanger 2 and supplied into the vehicle interior. During heating of the vehicle interior, the temperature of the heat exchanger 2 is detected and monitored by the temperature sensor 4.
Further, the carbon monoxide concentration of the air taken in by the blower 3 is detected and monitored by carbon monoxide gas sensors 5 and 6 upstream and downstream of the heat exchanger 2.

When the temperature sensor 4 detects abnormal heating of the heat exchanger 2 in this state, the controller 9 controls the fuel pump 8
At the same time, actuator 7 stops driving.
is driven to operate the switching door 10 and discharge the heated air to the outside of the vehicle. This prevents abnormally heated air from being supplied into the vehicle interior.

Further, when combustion gas leaks into the duct, carbon monoxide gas sensors 5 and 6 detect a change in the concentration of carbon monoxide. These carbon monoxide gas sensors are of a type in which the resistance value changes in response to changes in the concentration of carbon monoxide, for example, and changes in resistance value are sent as a signal to a controller (microcomputer). If a gas leak is detected,
Specifically, when the difference between the resistance values of the carbon monoxide gas sensors 5 and 6 exceeds a certain value, the driving of the fuel pump 8 is stopped, the heating of the rapid combustion heater is stopped, and switching is performed, as in the case of abnormal heating described above. The door is activated. The use of two gas sensors in this way can prevent malfunctions in cases where the air taken in is contaminated from the beginning due to the influence of atmospheric gases, such as on a congested road. This is to improve the accuracy of gas leak detection.

Next, control of the operation of the gas leak detection device of the present invention will be explained with reference to the system configuration diagrams of FIGS. 2 and 3 and the control flowcharts of FIGS. 4 and 5.

In FIG. 2, a temperature sensor 4, a carbon monoxide gas sensor 5 for atmospheric air, and a carbon monoxide gas sensor 6 for heating air are connected to A/D converters 20a, 20b,
20c, and the glow plug heater 11 and the switching door actuator 7 are also connected to the controller 9 so as to be controlled by the controller 9.

In FIG. 4, which is a control flowchart of this system configuration, first, the sensor outputs of each sensor 4, 5, and 6 are taken in (step a), and then these sensor outputs are processed (step b). . That is, linearization, carbon monoxide correction, etc. are performed. Next, the temperature of the heat exchanger is determined (step c), and if the temperature is not abnormally heated, the concentration of carbon monoxide is determined (step d).

As a result, if there is no abnormality, each step (a to d) is repeated again, but if abnormal heating or concentration exceeds, abnormality processing is performed, that is, stopping the rapid combustion heater and operating the switching door. (step e).

In FIG. 3, the output from the temperature sensor 4 is compared with a reference level 22a in a comparator 21a, and the difference signal is supplied to the controller, and the output of the atmospheric carbon monoxide gas sensor 5 and the heating air carbon monoxide The difference between the output of the gas sensor 6 and the output of the gas sensor 6 is determined by the differential amplifier 23, and the value is determined as the reference level 22.
b is compared with the comparator 21b and supplied to the controller 9, and the output of the heating air carbon monoxide gas sensor 6 is compared with the reference level 22c and the comparator 21.
c and then supplied to the controller 9. A glow plug heater 11 and a switching door actuator 7 are connected to the controller 9, as in the embodiment shown in FIG.

In FIG. 5, which is a control flowchart of this system configuration, it is determined whether the output of each comparator is normal or abnormal (step f), and if it is abnormal, the same abnormality processing as in step e is performed (step g).

(Effects of the Invention) As described above in detail, the present invention is configured to detect abnormal heating and gas leakage of the combustion heater and discharge gas-containing air to the outside.
It is possible to prevent human damage to the maximum extent possible.

Furthermore, since carbon monoxide detectors are provided upstream and downstream of the heat exchanger of the rapid combustion heater, the detection accuracy can be improved by eliminating the influence of carbon monoxide contained in atmospheric air.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the gas leak detection position of the present invention, Figs. 2 and 3 are system configuration diagrams thereof, and Figs. 4 and 5 are examples of the embodiments shown in Figs. 2 and 3. This is a control flowchart. 1... Combustor, 2... Heat exchanger, 3... Blower, 4... Temperature sensor, 5... Carbon monoxide gas sensor for atmospheric air, 6... Carbon monoxide gas sensor for heating air, 7... Switching door Actuator, 8...Fuel pump, 9...Controller, 10...Switching door, 11...Glow plug heater.

Claims (1)

[Claims] 1. First and second carbon monoxide detectors are provided on the air inflow side and air outflow side of the heat exchanger connected to the combustion heater, respectively, and the two carbon monoxide detectors are It is characterized by having means for comparing the outputs, and means for stopping the operation of the combustion type heater when the output of the second carbon monoxide detector increases by a predetermined value than the output value of the first detector. Gas leak detection device for vehicle combustion heaters. 2. The gas leak detection device for a combustion type heater for a vehicle as set forth in claim 1, further comprising means for discharging heating air from the heat exchanger to the outside of the vehicle when the operation of the combustion type heater is stopped.