JPH0299755A - Internal pressure controller for fuel tank - Google Patents

Abstract

PURPOSE:To improve the acceleration performance and restarting performance of an engine by installing a control valve midway in a vapor conduit and installing a valve opening and closing means which opens the control valve in the ordinary case and closes said control valve under a specific condition. CONSTITUTION:A vapor conduit 14 is installed between a fuel tank 5 and a canister 13. A control valve 31 is installed midway in the vapor conduit 14. A control unit 36 opens the control valve 31 at the ordinary times. When each detection value of a height sensor 34 and an opening degree sensor 35 is over each prescribed value, and the detection value of a pressure sensor 33 is less than a prescribed value, the control unit 36 closes the control valve 31. Therefore, the lowering of the boiling point of the fuel due to the lowering of the internal pressure in the fuel tank 5 in the highland traveling can be prevented, and the formation of a large quantity of vapor in the fuel tank 5 can be effectively prevented. Therefore, the acceleration performance and restarting performance of an engine can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention is suitable for controlling the internal pressure of a fuel tank, for example, by directing vapor generated in a fuel tank of an automobile to a canister and controlling the internal pressure. The present invention relates to a fuel tank internal pressure control device, and particularly to a fuel tank internal pressure control device that can prevent a large amount of vapor from being generated due to a drop in tank internal pressure when traveling at high altitudes.

[Background Art] Generally, in a fuel tank of an automobile or the like, fuel vaporizes and vapor is generated when the engine is stopped. This vapor contains a large amount of harmful components such as hydrocarbons (HC), and if released into the atmosphere, it will cause air pollution, so the vapor in the fuel tank is temporarily stored in a canister.

Therefore, FIGS. 3 and 4 show a prior art fuel injection device equipped with a canister.

In the figure, 1 is an automobile engine, and the engine 1 is composed of a cylinder LA, a piston IB, a combustion chamber 10, etc., and the engine 1 is provided with an injection valve 2 that injects fuel into the combustion chamber IC. At the same time, an intake manifold 3 for taking in outside air is provided in the combustion chamber IC, and a throttle valve 4 is provided in the middle of the intake manifold 3.

5 is a fuel tank for storing fuel 6; 7 is a fuel pump provided in the fuel tank 5; 8 is a fuel pipe connecting between the fuel pump 7 and the injection valve 2; A filter 9 and a pressure regulator 10 are provided. Note that the pressure regulator 10 guides the positive pressure or negative pressure in the collector 3A of the intique manifold 3 as a control pressure via the control pressure piping 11, and controls the fuel pressure according to the pressure in the intique manifold 3. , surplus oil is returned to the fuel tank 5 via the return pipe 12.

Reference numeral 13 denotes a canister containing activated carbon that temporarily absorbs evaporative gas as vapor generated by vaporization of the fuel 6. The inflow side of the canister 13 is connected to the fuel tank 5 via an inflow pipe 14 as a vapor conduit and a check valve 15. Connected to the inside.

Further, the canister 13 is provided with a purge control valve 13A, and the purge control valve 13A is connected to the intique manifold 3.
The back pressure introduction pipe 16 introduces the pressure near the throttle valve 4 out of the internal pressure as back pressure, and the evaporative gas stored in the canister 13 is purged (discharged) to the collector 3A at a downstream position of the throttle valve 4 in the intique manifold 3. It is connected to an outflow pipe 17. The canister 13 allows the evaporative gas generated in the fuel tank 5 to flow in through the inflow pipe 14 and stores it in activated carbon, while the purge control valve 13A is operated in the intique manifold 3 during off-idle when the throttle valve 4 starts opening. The valve is opened by introducing the negative pressure generated through the back pressure introduction pipe 16, and the stored evaporative gas is used as purge air to flow out into the outflow pipe 17.
purge into the intique manifold 3.

As shown in FIG. 4, the check valve 15 is formed into a cylindrical shape with a bottom, and includes a valve case 18 having a connecting port 18A protruding from the bottom side, and an open end of the valve case 18 that is closed. The lid body 19 has a protruding connection port 19A, and is movably provided in the valve case 18 via a valve spring 20, and has breathing holes 2LA, 2.
A check valve body 23 is attached to the valve support member 21 via a holding member 22 and is normally seated on the inner surface of the lid body 19 by a valve spring 20. , a breathing valve body 24 that opens and closes each breathing hole 2LA of the valve support member 21, and a connecting port 18A.

19A is connected in the middle of the inflow pipe 14. When the internal pressure of the fuel tank 5 becomes higher than atmospheric pressure due to evaporative gas, the check valve body 23 is activated by the valve spring 20.
The valve is opened against this, and the evaporative gas in the fuel tank 5 is allowed to flow into the canister 13 in the direction of arrow A. Further, the breathing valve body 24 opens when the internal pressure of the fuel tank 5 becomes lower than atmospheric pressure, and the breathing valve body 24 opens as outside air into the fuel tank 5 from the atmosphere inlet 13B of the canister 13 through the inflow pipe 14, each breathing hole 21A, etc. Air is allowed to flow in the direction of arrow B.

Furthermore, 25 indicates a control unit constituted by a microcomputer or the like, and the control unit 25 calculates the injection amount from the injection valve 2 and outputs an injection pulse signal having a predetermined duty based on this calculation to the injection valve 2. It has the function of

The fuel injection device according to the prior art has the above-mentioned configuration. First, when the engine 1 is started, the fuel pump 7 rotates to discharge the fuel 6 in the fuel tank 5 into the fuel pipe 8. This fuel 6 is injected from the injection valve 2 provided at the tip side of each branch pipe 3B based on the injection pulse signal of the control unit 25. The fuel pressure of the fuel 6 in the fuel pipe 8 is adjusted by the pressure regulator 10, and most of the fuel 6 becomes surplus oil and is returned from the pressure regulator 10 to the fuel tank 5 via the return pipe 12. In this case, the fuel pipe 8, the return pipe 12, etc. extend into the engine room of the vehicle, and the excess oil is exposed to the high temperature in the engine room, so this excess oil provides a cooling effect to the engine 1 etc.
The fuel is returned to the fuel tank 5 at a relatively high temperature.

In addition, as the fuel temperature in the fuel tank 5 increases, the fuel tank 5
The evaporative gas generated from the fuel 6 in the engine is sequentially stored in the canister 13 via the inflow pipe 14 and the check valve 15, and is discharged from the canister 13 via the outflow pipe 17 when the engine 1 is off-idle. It is purged into the manifold 3 and effectively utilized as part of the fuel.

[Problem to be solved by the invention]

By the way, in the above-mentioned conventional technology, the check valve 15 is merely provided in the middle of the inflow pipe 14 connecting the fuel tank 5 and the canister 13, and the check valve 15 is configured to check the internal pressure of the fuel tank 5 and the canister 13 side. Since the check valve body 23 etc. opens depending on the pressure difference between the atmospheric pressure and the atmospheric pressure, for example, 200
When driving a vehicle at high altitudes exceeding 0 m, the atmospheric pressure is 1
When the pressure drops below atmospheric pressure, the check valve body 23 opens according to the differential pressure, and the internal pressure of the fuel tank 5 is also reduced to below 1 atm, which lowers the boiling point of the fuel 6.
The fuel temperature inside the engine gradually increases as the temperature of the excess oil increases.

For this reason, in the conventional technology, when driving at high altitudes, a large amount of evaporative gas is generated as vapor from the fuel 6 in the fuel tank 5 as the internal pressure of the fuel tank 5 decreases and the fuel temperature increases, and this evaporative gas is led out to the canister 13 and While filling the canister 13, a part of it is sucked into the fuel pump 7 in the fuel tank 5, causing a cavitation lock in the fuel pump 7, and causing the injection valve 2 to inject evaporated gas together with the fuel 6. This has the drawback that the air-fuel ratio is partially affected, causing poor acceleration and poor restart.

The present invention was developed in view of the above-mentioned drawbacks of the prior art.The present invention can prevent the pressure inside the fuel tank from being depressurized and the generation of a large amount of vapor (evaporative gas) due to the rise in fuel temperature when driving at high altitudes. The present invention provides a fuel tank internal pressure control device that can improve acceleration performance, restartability, etc.

[Means for Solving the Problems 1] In order to solve the above-mentioned problems, the present invention includes a fuel tank in which a fuel pump is provided, and a fuel vapor generated in the fuel tank to be led out to a canister. A vapor conduit provided between the fuel tank and the canister, a control valve provided in the middle of the vapor conduit to control opening and closing of the flow path of the vapor conduit, and a control valve located between the control valve and the fuel tank. a surge tank that is provided in the middle of the vapor conduit and temporarily accommodates vapor generated in the fuel tank; and a pressure sensor that detects the pressure in the surge tank.
A temperature sensor that detects the fuel temperature in the fuel tank, an altitude sensor that detects the altitude when traveling at high altitudes, and the control valve is normally opened when the detected values by the altitude sensor and temperature sensor are equal to or higher than a predetermined value. , and a valve opening/closing means for closing the control valve when the detected value by the pressure sensor is less than or equal to a predetermined value 9 [Operation] With the above structure, when the fuel temperature rises while driving at high altitudes, surges occur. Since the control valve is closed according to the pressure inside the tank, it is possible to prevent the internal pressure of the fuel tank from decreasing to the pressure inside the surge tank, for example, 1 atmosphere or less, and evaporative gas is generated as vapor from the fuel in the fuel tank. It is possible to effectively prevent this from becoming easier.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2. In the embodiment, the same components as those of the prior art shown in FIGS. 3 and 4 are given the same reference numerals, and their explanations will be omitted.

In the figure, reference numeral 31 indicates a control valve located between the canister 13 and the check valve 15 and provided in the middle of the inflow pipe 14 as a vapor conduit. , a control unit 36 to be described later.
The flow path of the inflow pipe 14 is opened and closed based on the signal from the inflow pipe 14. 32 is located between the control valve 31 and the check valve 15 and is provided in the middle of the inflow pipe 14.
The surge tank 32 temporarily stores evaporative gas as vapor generated from the fuel 6 in the fuel tank 5, and when the control valve 31 is opened, the evaporative gas is transferred into the canister 13 through the inflow pipe 14. It is designed to flow in sequentially.

Reference numeral 33 indicates a pressure sensor provided in the surge tank 32, and the pressure sensor 33 detects the pressure P in the surge tank 32 and outputs a detection signal corresponding to this pressure P to the control unit 36. There is. Reference numeral 34 indicates an altitude sensor provided on the body of the vehicle, etc. The altitude sensor 34 is configured using a barometer or the like, detects the altitude H when the vehicle is traveling at high altitude, and sends the detection signal to the control unit. 36 indicates a temperature sensor provided in the fuel tank 5. The temperature sensor 35 detects the fuel temperature T in the fuel tank 5 and outputs a detection signal to the control unit 36.

Furthermore, 36 indicates a control unit constituted by a microcomputer etc., the input side of the control unit 36 is connected to the pressure sensor 33, the altitude sensor 34, the temperature sensor 35 etc., and the output side is connected to the injection valve 2 (
(see FIG. 3) and the control valve 31. The control unit 36 has a function of calculating the injection amount of fuel injected from the injection valve 2 as in the prior art, and also stores a program shown in FIG. 2 in its memory circuit, and controls the control valve. 31 opening and closing processing operations are performed.

The internal pressure control device for the fuel tank 5 according to this embodiment has the above-mentioned configuration. Next, the opening and closing process of the control valve 31 by the control unit 36 will be explained with reference to FIG.

First, the processing operation is started with the start of the engine 1, and in step 1, the altitude sensor 34 detects the vehicle's running altitude H.
, move to step 2, and set the altitude H to, for example, 2 above sea level.
It is determined whether the altitude is higher than a predetermined altitude H0 of 000 m. Then, in step 2, if it is determined as YES, the vehicle is traveling at a high altitude of 2000m or more above sea level, so step 3
The fuel temperature T in the fuel tank 5 is read from the temperature sensor 35, and in step 4 it is determined whether the fuel temperature T is equal to or higher than a predetermined temperature of 10, for example, 50''C. When it is determined that Mo?MT is 5
Since the temperature is 0°C or higher, proceed to step 5 and read the pressure P in the surge tank 32 from the pressure sensor 33.
In step 6, the pressure P or the predetermined pressure P is set. For example, it is determined whether the pressure is 1 atm or less.

Then, when it is determined as rYESJ in step 6,
The pressure P in the surge tank 32 becomes 1 atmosphere or less, and the pressure in the fuel tank 5 communicating with the surge tank 32 via the inflow pipe 14 is also reduced to 1 atmosphere or less.
Proceeding to step 7, the control valve 31 is closed, and the evaporative gas (
vapor) from flowing into the canister 13 via the inflow pipe 14. That is, when the vehicle is traveling at a high altitude, the surrounding atmosphere itself becomes under pressure lower than 1 atm, and the inside of the canister 13 is also exposed to this low pressure. However, in this case, the control valve 31 is closed and the canister 13
Since the connection between the surge tank 32 and the surge tank 32 is cut off, it is possible to prevent the pressure inside the surge tank 32 from dropping to a pressure lower than 1 atmosphere, and the surge tank 32 is communicated with the surge tank 32 via the inflow pipe 14 and the check valve 15. The internal pressure within the fuel tank 5 can be maintained at about 1 atmosphere, and the generation of evaporative gas within the fuel tank 5 can be suppressed.

Furthermore, when the determination in step 2 is "NO", the vehicle is traveling on a road less than 2000 m above sea level, so the internal pressure of the fuel tank 5 will not be reduced to below the predetermined pressure P0 (1 atm), and in step 8 Then, the control valve 31 is opened. If the determination in step 4 is "No", the fuel temperature in the fuel tank 5 is low and the possibility of evaporative gas being generated in the fuel tank 5 is low, so in this case as well, the process moves to step 8 and the control valve 31 is opened. Let me speak. Also, if the determination in step 6 is "NO", the surge tank 32
Since the pressure inside the fuel tank 5 is higher than 1 atm, in this case, the process moves to step 9 and the control valve 3
1 is opened to allow the evaporative gas in the fuel tank 5 to flow into the canister 13 via the surge tank 32, thereby preventing the fuel tank 5 from being filled with a large amount of evaporative gas.

Therefore, in this embodiment, when the vehicle is running at high altitude, the fuel temperature is 50'.
Since the control valve 31 is closed when the pressure in the surge tank 32 decreases to 1 atm or less, the internal pressure of the fuel tank 5 is reduced during high altitude driving, and the pressure in the fuel 6 is reduced. It is possible to prevent the boiling point from decreasing, effectively suppress the generation of a large amount of evaporative gas from the fuel 6 in the fuel tank 5, and solve problems such as poor acceleration and restart of the engine 1 due to vapor lock etc. can do.

Note that in the program shown in FIG. 2, steps 7, 8, and 9 are specific examples of the valve opening/closing means.

[Effects of the Invention] As detailed above, according to the present invention, the control valve provided in the middle of the vapor conduit is always open, and when the detected values by the altitude sensor and the temperature sensor are above a predetermined value, the pressure sensor is detected. Since the valve is configured to close when the detected value is less than a predetermined value, it is possible to prevent the internal pressure of the fuel tank from being reduced during high-altitude driving and the boiling point of the fuel to decrease, and to prevent a large amount of vapor from being generated within the fuel tank. It has various effects such as being able to effectively suppress the engine acceleration and restartability of the engine.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is an overall configuration diagram showing an internal pressure control device for a fuel tank, FIG. 2 is a flowchart showing control valve opening and closing processing, and FIG. Figure and 4th
The figures show the prior art, FIG. 3 is an overall configuration diagram of a fuel injection device, and FIG. 4 is a longitudinal sectional view showing a check valve. 2... Injection valve, 5... Fuel tank, 7... Fuel pump, 13... Canister, 14... Inflow pipe (vapor conduit), 15... Check valve, 31... Control Valve, 32...Surge tank, 33...Pressure sensor. Flute diagram °l

Claims (1)

[Claims] A fuel tank having a fuel pump provided therein, a vapor conduit provided between the fuel tank and the canister to conduct fuel vapor generated in the fuel tank to the canister, and a vapor conduit provided midway through the vapor conduit. a control valve provided in the vapor conduit for controlling opening and closing of a flow path of the vapor conduit; and a control valve provided in the middle of the vapor conduit located between the control valve and the fuel tank;
a surge tank that temporarily stores vapor generated in the fuel tank; a pressure sensor that detects the pressure in the surge tank; a temperature sensor that detects the fuel temperature in the fuel tank; an altitude sensor for detecting an altitude sensor, and the control valve is normally opened, and the control valve is closed when the detected value by the altitude sensor and the temperature sensor is above a predetermined value, and the detected value by the pressure sensor is below a predetermined value. A fuel tank internal pressure control device comprising a valve opening/closing means.