JPS6259228B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention supplies fuel from a fuel tank to an engine side using a motor-driven fuel pump, and
This invention relates to a device for electrically controlling the cooling of fuel temperature in a fuel circulation system of an automobile, which is provided with a fuel circulation system that returns fuel that is not consumed (combusted) by the engine to the fuel tank side. The purpose of this is to prevent fuel vapor lock by circulating the fuel intermittently when the fuel temperature is high immediately after the engine has stopped.
By increasing the cooling effect of fuel in the circulation system,
The purpose is to suppress the rise in fuel temperature.

If the temperature of the fuel supplied to the engine rises above a certain value, vapor lock may occur in the injector, making it impossible to restart the engine. Especially when gasohol is used as the fuel, its limit temperature may drop. Therefore, it is necessary to suppress the fuel temperature rise to a lower level. As a solution to the above problem, a blower is installed to cool the injector, and after the engine has stopped, a motor is used to rotate the blower to cool it down. However, since the blower is provided separately, it is expensive and takes up a lot of space. Problems arose, such as not being able to install it.

This invention attempts to cool the fuel by circulating it, and when the ignition switch is turned off, the temperature switch becomes functional and detects the temperature of the fuel supplied to the injector. If the preset upper limit is reached, the temperature switch is activated to operate the drive circuit during that time, and the drive circuit limits the drive time and operates the fuel pump motor intermittently within that limited time. Therefore, the fuel is intermittently circulated in the circulation system via the fuel tank, and when the fuel is stopped, the fuel absorbs heat from the heating section, and when it is circulating, the fuel is absorbed in the circulation system such as the fuel tank. Heat exchange is performed efficiently through repeated divergence.

Embodiments of the present invention will be described below with reference to the drawings.

In Figure 1, relay RL ₁ has its coil CL ₁
is connected to the ignition contact IG of ignition switch SW ₁ . When the common contact C ₀ and the ignition contact IG are connected, the coil
CL ₁ receives battery power E and is energized, at which time the normally open relay contact a ₁ closes to operate the ignition circuit load L, and the normally closed relay contact b opens.

Note that the contact OFF is an open contact.

Contacts ACC and ST are accessory contacts and starter contacts, respectively, and their connection circuits are omitted. The timer circuit T is connected in series with a normally open first temperature switch SW _T1 (temperature detection means),
When relay contact b is closed, when first temperature switch SW _T1 is closed, it receives power E and operates for a certain period of time, during which time transistor T
I am getting _r1 to work. The first temperature switch SW _T1 closes when the temperature of the fuel supplied to the injector (not shown) reaches a preset upper limit, and opens when the temperature drops by a predetermined temperature below the upper limit. It has been adjusted to The intermittent drive circuit IN operates while the transistor T _r1 is operating to cause the transistor T _r2 to operate intermittently, and is composed of, for example, a multivibrator circuit, and controls the transistor T _r2 to operate the motor for a certain period of time. drive. After that, the motor is kept inactive for several minutes (the motor is stopped for a certain period of time), and the process is repeated. relay
RL ₂ is a normally open relay contact when the coil CL ₂ is connected in series with the relay contact b, the second circuit switch SW _T2 , the shock switch SW _G , and the transistor Tr ₂ , and when these are in a conductive state. Close a ₂ ,
A fuel pump motor M is driven by a power source E via a diode D. Therefore, the drive cycle is based on the intermittent operation of the intermittent drive circuit IN, and its duration is determined by the set time of the timer circuit T. The motor drive circuit DV is shown surrounded by a chain line and consists of the above-mentioned timer circuit T, intermittent drive circuit IN, and transistors Tr ₁ and Tr ₂ . The second temperature switch SW _T2 is the first temperature switch
It is a normally open switch that works in conjunction with SW _T1 , and the impact switch SW _G is a normally closed switch that operates for safety by detecting an abnormal impact such as a collision. Note that the fuel pump motor M is also connected in parallel to the ignition circuit load L without intervening a diode D or the like in order to perform normal movement during engine operation.

The operation of the above configuration will be explained below. Ignition switch SW ₁ common contact C ₀
and ignition contact IG are connected, contact a ₁ of relay RL ₁ is closed and contact b is open, fuel pump motor M is operated continuously, ignition circuit load L is energized, and the engine is operated. become a state. From this state, when the common contact C ₀ of the ignition switch SW ₁ is switched to the open contact OFF, the contact a ₁ of the relay RL ₁ opens as shown in Figure 1, and the contact b closes, causing the ignition circuit load. L is de-energized, the engine stops, and the fuel pump motor M also stops, temporarily stopping fuel supply and circulation. If the fuel pump motor M remains stopped, the fuel temperature t of the injector will rise as time m passes, as shown by the temperature characteristic A in FIG. 2, and there is a risk that vapor lock will occur at the temperature reached. In this invention, in order to lower this ultimate temperature, the temperature switches SW _T1 and SW _T2 in FIG. 1 are adjusted so that they close when the injector fuel temperature t in FIG. 2 reaches the set temperature te. can be,
Therefore, after the engine stop time m ₀ , the temperature t increases according to the temperature characteristic A, and when it reaches the set temperature te, the timer circuit T operates at time m ₁ and the transistor Tr ₁ becomes conductive. The intermittent drive circuit IN is operated by the conduction of the transistor Tr ₁ , the transistor Tr ₂ is intermittently made conductive, the contact a ₂ of the relay RL ₂ is intermittently opened and closed, and the fuel pump motor M is intermittently driven. Due to the intermittent drive, since cooled fuel is supplied from the fuel tank at the beginning of the drive, the temperature drops rapidly as shown in temperature characteristic B, and then becomes approximately constant. Then, during the stop period, the temperature increases similarly to temperature characteristic A, and this is repeated. The timer circuit T is set to elapsed time m _T from time m ₁ so that this can be repeated a necessary number of times, for example, several times. During the fuel circulation stop, the fuel sufficiently absorbs the heat of the injector, and the fuel tank Diverging in,
When circulated, these fuels exchange each other, so heat exchange becomes efficient, and the temperature reached is much lower than in temperature characteristic A, eliminating the risk of vapor lock.

As described above, according to the present invention, an efficient cooling effect can be obtained using an electric circuit without adding a mechanical part as a fuel cooling device, so that an effective and easy means for countering vapor lock can be provided. . Furthermore, by intermittently driving the motor and intermittently driving the fuel pump, even if the temperature of the fuel does not drop to the predetermined temperature, it can be maintained below the set temperature and vapor lock can be reliably prevented. Also,
By driving the motor only for a predetermined period of time and driving the fuel pump for a predetermined period of time, it is possible to prevent the battery from being over-discharged, and by driving the motor intermittently within a predetermined period of time, the fuel pump can be driven intermittently within a predetermined period of time. By doing so, you can lengthen the time it takes to consume a predetermined amount of battery power, and even if the interval between engine stop and restart is longer, the temperature will be maintained below the set temperature, making it easier to restart. A certain period of time can be extended while satisfying the condition that the battery is not over-discharged.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram showing an embodiment of the present invention;
FIG. 2 is a temperature rise characteristic diagram. SW _T1 , SW _T2 ...Temperature switch, DV...Motor drive circuit, M...Fuel pump motor.

Claims (1)

[Claims] 1. A fuel circulation system is provided in which fuel is supplied from the fuel tank to the engine by a motor-driven fuel pump, and fuel not consumed by the engine is returned to the fuel tank. , a motor drive circuit that is provided with temperature detection means for detecting the temperature of the fuel in a portion of the fuel circulation system that is affected by the heat of the engine, and that operates the motor in response to an operation signal from the temperature detection means when the engine is stopped. The fuel cooling control device for a vehicle is provided with a temperature detecting means, wherein the temperature detecting means turns on when the upper limit of the set value is reached, turns off when the temperature drops by a predetermined value from the upper limit of the set value, and turns off while it is on. The motor drive circuit is provided to be capable of outputting an operation signal, and the motor drive circuit includes an intermittent drive circuit that performs intermittent drive in which the motor is driven for a certain period of time and then stopped for a certain period of time, and a circuit that receives the operation signal when the engine is stopped. and a timer circuit for operating the intermittent drive circuit for a predetermined period of time.