HEATING CONTAINER APPARATUS

Abstract: Heating container apparatus for supplying heated air into a heating container (20) on an automobile or other vehicle for heating or keeping warm the cargo in the heating container, comprises a burner (14) including an atomizing glow plug (18) and an ignition glow plug (13), a heat exchanger (23) for recovering heat generated by the burner, an air blower (16) for feeding heated air into the container, a temperature control device (11), and a voltage control circuit (2-10). The voltage control device is supplied with electric power from a commercial AC power supply line to produce a voltage equal to the voltage of a power supply mounted on the automobile for thereby keeping the interior of the heating controller warm even when the engine of the automobile is stopped. The temperature control device maintains the temperature in the heating container within a suitable temperature range at all times.

Description: The present invention relates to a heating container apparatus for supplying heat to a heating container mounted on a vehicle to keep the contents of the heating container warm. One known heating container apparatus used on a vehicle for transporting foods or chemicals is disclosed in Japanese Laid-Open Utility Model Publication No. 58-130809. The foods or chemicals carried on the vehicle are heated or kept warm by the heat of the exhaust gas emitted from the engine of the vehicle. Another conventional heating container apparatus uses as a heat source the energy of the engine coolant. Some foods, which are required to be delivered early in the morning, should preferably be loaded on the vehicle in the night prior to delivery. However, where the exhaust gas or the engine coolant is utilised as the heat source, it would be quite difficult or almost impossible to heat the cargo or keep it warm for a long period of time throughout the night while the vehicle is at rest, because of the limited capacity of the battery, for example. Therefore, it has been customary in most cases to load the freight early in the morning just prior to transportation. US-A-3024835 discloses a vehicle heater having a burner, a heat exchanger, fans for circulating air, and a thermostat for controlling operation of the heater. FR-A-2372533 discloses a voltage controller for controlling the voltage supplied by an external power supply to a heater for caravans. In view of the aforesaid drawbacks of the conventional heating container apparatus, it is an object of the present invention to provide a heating container apparatus for keeping the interior of a heating container at a desired temperature by operating a control device with electric power from a power supply other than the vehicle-mounted power supply, when the vehicle is at rest for a long period of time, using an improved voltage control means. According to the invention there is provided an automotive heating container apparatus for supplying heat to a heating container mounted on a vehicle to keep the contents of the heating container warm, comprising a burner for igniting fuel; an atomizer for atomizing fuel to be supplied to the burner; a first air blower device for supplying air to the burner; a second air blower device for introducing air into the heating container; a heat exchanger for recovering heat generated by the burner to heat air to be introduced into the heating container; and, a control device for controlling the air to be introduced into the heating container based on a temperature signal from a container temperature sensor disposed in the heating container; characterised by: voltage control means for controlling the voltage supplied by an external AC power supply so that the voltage of the AC power supply can be selected to be equal to a given voltage of the vehicle-mounted power supply, and for operating the control device with electric power from the AC power supply when the engine of the vehicle is stopped; the voltage control means including a switching element, a rectifying element, a phase control thyristor, and a protective circuit for protecting the phase control thyristor against excessive voltage. Hence, while the vehicle engine is running, electric power from the vehicle-mounted power supply is employed, and while the vehicle is at rest for an appreciable period of time, electric power from a commercial AC power supply is employed. The interior of the heating container can be kept at a suitable temperature at all times by the electric power supply thus provided. As described above, during stoppage of the automobile for an appreciable time interval, electric power is supplied from a commercial power supply available at home, rather than from the vehicle battery, to keep the interior of the heating container at the desired temperature. Therefore, foods or the like can be loaded on the vehicle in the previous night, and can be delivered early in the next morning immediately without any loading operation. An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which Fig. 1 is a schematic diagram of a burner device for use with an automotive heating container according to the present invention; and Fig. 2 is a flowchart of an operation sequence of temperature control for the automotive heating container. Fig. 1 shows a power supply which can be used in place of a vehicle-mounted battery 21 when the engine of an automobile is stopped. The power supply 30 is supplied with AC power at, say, 100V via a plug 1 to produce DC power at 24V or 12V equal to the vehicle battery voltage, the DC power at 24V or 12V being supplied via wires 3 and a controller 11 to an atomizing glow plug 18, an ignition glow plug 13, a first blower 15, a second blower 16, and a fuel pump 17. The power supply 30 comprises a thyristor 2, a diode 4, a resistor 5, a zener diode 6, a unijunction transistor 7, a protective circuit 8 for protecting the thyristor 2 from excessive voltage, a resistor 9, and a capacitor 10. The thyristor 2 serves to rectify the AC power only when a positive voltage is applied to its gate. The diode 4 and the resistor 5 apply a rectified positive voltage to the cathode of the zener diode 6, which keeps the voltage thereacross (anode-to-cathode voltage) in a voltage range from 10V to 20V. The unijunction transistor 7, the resistor 9, and the capacitor 10 jointly constitute a charging/discharging circuit which, on discharge, applies a positive voltage to the gate of the thyristor 2 to render the thyristor conductive. The time of one cycle of the charging/discharging circuit is established by appropriately selecting the time constant of the resistor 9 and the capacitor 10. Therefore, the power supply 30 can produce a voltage equal to the 24V or 12V voltage of the battery 21 by selecting the breakdown voltage of the zener diode 6 and the time constant of the resistor 9 and the capacitor 10. The controller 11 is in the form of an electronic control device which is programmed according to an operation sequence (described later) for controlling the atomizing glow plug, the ignition glow plug, the first and second blowers, and the fuel pump. A burner 14 has an atomizer 12 for atomizing fuel supplied from the fuel pump 17 by heating the fuel with the atomizing glow plug 18, and the ignition glow plug 13 for igniting a mixture of the fuel atomized by the atomizer 12 and the air introduced by the first blower 15. The combustion gas produced by the burner 14 is discharged through a heat exchanger 23 into the atmosphere. The second blower 16 draws in air and supplies that air to the heat exchanger 23, from which hot air is delivered into a heating container 20. A container temperature sensor 19 senses the temperature in the heating container 20. Fig. 1 also shows a battery 21, a changeover switch 22 and a combustion sensor 24. Temperature control for the automotive heating container will now be described with reference to the flowchart of Fig. 2. In order to operate the heating container 20 when the engine is stopped the changeover switch 22 is actuated to select the power supply 30, and the plug 1 is connected to a socket for receiving AC power from the 100V supply. The temperature TR in the heating container 20 is measured by the container temperature sensor 19. A step a ascertains whether the temperature TR is lower than an upper limit such as 20°C. If yes, then the ignition glow plug 13 is turned on in a step b , which is followed by a step c which checks whether or not the ignition glow plug 13 is operating normally. If the ignition glow plug 13 is operating normally, then control proceeds to a step d in which a fuel switch (not shown) is turned on, and then to a step e in which the atomizing glow plug 18 is turned on. A next step f ascertains whether the atomizing glow plug 18 is operating normally or not. If it is operating normally, then the first and second blowers 15 and 16 are turned on in respective steps g and h . The combustion sensor 24 is turned on 30 seconds later, and whether combustion is normal or not is ascertained in a step i . If it is not normal in each of the steps c , f and i , control goes to a step l in which a failure buzzer (not shown) is energized. A step j then ascertains whether the container temperature TR is higher than a lower limit such as 10°C. If yes, then heating of the container is continued for a time t₁ in a step k . If the container temperature TR is lower than the lower limit, then control goes to a step o which brings the fuel switch into a second position to increase the amount of fuel supplied. Thereafter, the first and second blowers 15 and 16 are brought into a second position in respective steps p , q to increase the amount of air supplied to cause the container temperature TR to be raised quickly up to 20°C. Then, a step r ascertains whether the temperature TR in the heating container is lower than 60°C, for example. If the temperature TR is lower than 60°C, then control goes to the step k . If the temperature TR is higher than 60°C due to a failure of the combustion control system for the heating container apparatus of the invention, then the failure buzzer is energized in a step s . If the container temperature TR is higher than the upper limit of 20°C, then control goes to a step m in which operation of the heating container is stopped. The step m is followed by a step n which keeps the heating container inoperative for a time t₂. With the arrangement of the present invention, as described above, while the automobile is being held at rest for a long period of time, electric power is supplied not from the automobile-mounted battery, but from a commercial power supply available at home, for keeping the automotive heating container in a desired temperature range. Therefore, a cargo such as foods can be loaded in the previous night, kept at a desired temperature through the night, and delivered early in the next morning without any loading operation required. While in the above embodiment a thyristor phase control circuit is employed as the power supply 30, another constant-voltage power supply employing a transformer and rectifier circuit,or a thyristor rectifier, capable of producing DC power at 24V or 12V from a 100V AC power supply may be employed instead of the illustrated power supply. Clearly the AC power supply may alternatively be 220V or 240V, or any other available AC supply voltage.

Claims: An automotive heating container apparatus for supplying heat to a heating container mounted on a vehicle to keep the contents of the heating container warm, comprising a burner (14) for igniting fuel; an atomizer (18) for atomizing fuel to be supplied to the burner; a first air blower device (15) for supplying air to the burner; a second air blower device (16) for introducing air into the heating container; a heat exchanger (23) for recovering heat generated by the burner to heat air to be introduced into the heating container; and, a control device (11) for controlling the air to be introduced into the heating container based on a temperature signal from a container temperature sensor (19) disposed in the heating container; characterised by: voltage control means (2,6-10) for controlling the voltage supplied by an external AC power supply (30) so that the voltage of the AC power supply can be selected to be equal to a given voltage of the vehicle-mounted power supply, and for operating the control device with electric power from the AC power supply when the engine of the vehicle is stopped; the voltage control means including a switching element (7), a rectifying element (14), a phase control thyristor (2), and a protective circuit (8) for protecting the phase control thyristor against excessive voltage. Apparatus according to claim 1, wherein the voltage control means (2,6-10) comprises a switching-regulator-type constant-voltage device. Apparatus according to claim 1 or claim 2, wherein the voltage control means (2,6-10) comprises a phase-control switching-regulator-type constant-voltage device employing a thyristor (2). Apparatus according to any of the preceding claims, wherein the burner (14) includes an atomizing glow plug (18), an ignition glow plug (13), and a combustion sensor (24). Apparatus according to any of the preceding claims, wherein the control device (11) comprises means for comparing the temperature in the heating container as detected by said container temperature sensor (19) with a predetermined upper limit temperature and for turning on the ignition glow plug (13) when the temperature in the heating container is lower than the predetermined upper limit temperature; means for ascertaining whether the ignition glow plug (13) is operating normally, for giving a command to turn on a fuel switch to supply fuel to said burner and also to turn on the atomizing glow plug (18) when the ignition glow plug is operating normally, and for indicating a failure when the ignition glow plug is not operating normally; means for ascertaining whether the atomizing glow plug is operating normally, for giving a command to turn on the first and second blowers and, upon elapse of a certain period of time, a command to operate the combustion sensor if the atomizing glow plug is operating normally, and for indicating a failure when the atomizing glow plug is not operating normally; means (24) for ascertaining whether combustion is effected in the burner after the combustion sensor has been operated, and for indicating a failure when no combustion is effected in the burner; and, means for stopping heating of the container and for keeping the heating inoperative for a given period of time if the temperature in the heating container is higher than the upper limit temperature. Apparatus according to claim 5, wherein the control device further includes means for comparing the temperature in the heating container as detected by the container temperature sensor (19) with a predetermined lower limit temperature and for continuing heating of the container for a given period of time when the temperature in the heating container is higher than the lower limit temperature; means for bringing the fuel switch into a second position to increase the amount of fuel supplied and bringing the first and second blowers into a second position to increase the amount of air supplied for raising the temperature in the heating container quickly up to the upper limit temperature, when the temperature in the heating container is lower than the lower limit temperature; and, means for comparing the temperature of air in the heating container with a prescribed temperature higher than the upper limit temperature, for keeping the heating container operated for a given period of time when the temperature of the hot air is lower than the prescribed temperature, and for indicating a failure if the temperature of the hot air is higher than the prescribed temperature.

Inventors: KAWAMURA, KIDEO
Applicants: ISUZU MOTORS LIMITED
Application year: 1986
Main classification: B60H1
IPC codes: B60H1, F23N1