JPH0355668B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel pump failure detection device used for self-diagnosing failure of a fuel pump that supplies fuel to an internal combustion engine for an automobile, for example.

[Conventional technology]

4 and 5 show fuel pumps according to the prior art.

In the figure, 1 is a fuel tank containing fuel F, 2 is a fuel pump provided in the fuel tank 1, 3 is a casing that constitutes the main body of the fuel pump 2, and a DC motor is installed in the casing 3. A motor section 4 constituted by, etc., and the motor section 4
A roller vane type or turbine type pump unit 5 which is rotationally driven by a roller vane type or turbine type pump unit 5 is built in. Further, a suction port 3A for the fuel F is provided at the lower end of the casing 3, and a discharge port 3B for the fuel F, a vapor discharge port 3C, a relief port (not shown), etc. are provided at the upper end. A filter 6 is connected to the suction port 3A of the casing 3 via a hose or the like, and the fuel F in the fuel tank 1 flows from the suction port 3A into the casing 3 through the filter 6 by the rotation of the pump section 5. It is designed to be sucked in and discharged from the discharge port 3B.

Reference numeral 7 indicates a discharge pipe connected to the discharge port 3B and led out from inside the fuel tank 1, and the tip side of the discharge pipe 7 is connected to a fuel injection valve such as an injector (both not shown) via a pressure regulator or the like. The fuel injector is connected to the fuel injector 3B, and the fuel F discharged from the discharge port 3B is supplied to this fuel injection valve. Further, 8 indicates a check valve for maintaining residual pressure provided in the discharge port 3B, and the check valve 8 is
The fuel F is made to flow only from the inside of the casing 3 toward the inside of the discharge pipe 7. The check valve 8 is designed to maintain the residual pressure within the discharge pipe 7 at, for example, about 2.5 kg/cm ² .

Reference numeral 9 indicates a hot restart valve provided at the vapor discharge port 3C of the casing 3, and the hot restart valve 9 prevents the vapor generated in the casing 3 for the reasons described below, during startup of the motor section 4, etc. The vapor is discharged into the fuel F in the fuel tank 1 via the vapor discharge hose 14. Here, the hot restart valve 9 is the fifth
As shown in the figure, a stepped cylindrical valve seat member 11 is fixed in the vapor discharge port 3C via a stopper washer 10, etc., and has a valve seat 11A formed on the lower end side.
and seated on and off the valve seat 11A of the valve seat member 11,
It consists of a valve body 12 that opens and closes the vapor discharge port 3C, and a valve spring 13 that is provided between the valve body 12 and the valve seat member 11 and normally holds the valve body 12 in an open state. , the valve body 12 has the pressure inside the casing 3,
For example, when the pressure exceeds about 0.2 kg/cm ² , the valve closes against the valve spring 13.

Furthermore, 14 indicates a vapor discharge hose for discharging vapor from the vapor discharge port 3C into the fuel F of the fuel tank 1, and one end side of the discharge hose 14 is connected to the protruding end side 11B of the valve seat member 11. The other end extends to the bottom of the fuel tank 1, and a filter 15 is attached thereto.

In the fuel pump 2 configured as described above, the motor section 4 is activated when the engine is started by the engine switch, and the rotation of the pump section 5 causes the fuel F in the fuel tank 1 to be pumped through the filter 6 from the suction port 3A to the casing. Suction into 3, discharge port 3B
The fuel is then supplied under pressure to the fuel injection valve via the discharge pipe 7 and the like. When the engine is stopped, the motor section 4 is also stopped, and the check valve 8 in the discharge port 3B is
is the discharge pipe 7 in preparation for the next start of the engine.
The valve is closed to maintain the residual fuel pressure at, for example, about 2.5Kg/cm ² .

By the way, if the casing 3 of the fuel pump 2 protrudes above the oil level of the fuel F, the fuel in the casing 3 will be gradually discharged into the fuel tank 1 from the suction port 3A after the pump section 5 stops. The inside of the casing 3 becomes negative pressure, and vapor of fuel F is generated inside the casing 1. On the other hand, while the engine is running, the inside of the engine room is cooled to around 70℃ by the cooling fan, but when the engine is stopped, the cooling fan also stops.
The temperature in the engine room increases due to the residual heat of the engine, and the temperature of the fuel F in the fuel tank 1 also increases temporarily.

As a result, the fuel F remaining in the casing 3 becomes more likely to vaporize together with the negative pressure in the casing 3, and a significant amount of vapor is generated in the casing 3. If the engine is restarted in this state and the vapor in the casing 3 is discharged from the discharge port 3B to the fuel injection valve via the discharge pipe 7, etc., the air-fuel ratio will drop and the engine will run smoothly. It becomes impossible to restart the computer.

Therefore, a hot restart valve 9 is provided at the vapor discharge port 3C of the casing 3, and by keeping the valve body 12 of the valve 9 open at all times, the vapor in the casing 3 is discharged through the vapor discharge hose 14. The vapor is discharged into the fuel F in the fuel tank 1, and this vapor is prevented from being discharged into the discharge pipe 7. The valve body 12 is configured such that the pressure inside the casing 3 increases after the motor section 4 is started, for example.
If it exceeds about 0.2 kg/cm ² , the valve seats against the valve spring 13 and closes on the valve seat 11A of the valve seat member 11, so the fuel pressure inside the casing 3 further increases, causing the check valve 8 to open. Thus, only the fuel F can be discharged into the discharge pipe 7 from the discharge port 3B.

[Problem that the invention seeks to solve]

However, in the prior art described above, the valve seat member 11
If a foreign object enters between the valve seat 11A and the valve body 12, or the valve body 12 or the like deteriorates, the valve body 12 does not sit on the valve seat 11A even after the vapor is discharged, and the inside of the casing 1 The fuel F is at the vapor outlet 3C.
from the fuel tank 1 via the vapor discharge hose 14.
A large amount may be returned within the body. As a result, the fuel pressure inside the casing 3 cannot be increased, and the fuel F is discharged from the discharge port 3B into the discharge pipe 7.
There is a problem in that the flow rate of the engine decreases significantly, and in some cases, it becomes impossible to secure the minimum discharge flow rate necessary to start the engine and drive the car at a speed of, for example, 40 km/h.

The present invention was developed in view of the above-mentioned problems with the prior art, and the internal pressure of the fuel pump casing is set within a predetermined time after the pump starts due to the deterioration of the seal of the hot restart valve, the adhesion of foreign matter, etc. It is an object of the present invention to provide a failure detection device for a fuel pump capable of self-diagnosing a failure of the hot restart valve when the pressure is not reached.

[Means for Solving the Problems] In order to solve the above problems, the present invention incorporates a motor section and a pump section in a casing, and discharges fuel through a check valve for maintaining residual pressure. A fuel pump is provided with a hot restart valve that discharges vapor in the casing when the pump section is started, a pressure detection means that detects the fuel pressure in the casing of the fuel pump, and a voltage is applied to the motor section of the fuel pump. A pressure increase time measuring means for measuring the pressure increase time after application, and a comparison between the pressure detected by the pressure detection means and whether or not the pressure detected by the pressure detection means has reached a predetermined set pressure after a predetermined pressure increase time by the pressure increase time measurement means has elapsed; The hot restart valve is characterized by comprising failure detection means for detecting a failure of the hot restart valve when the predetermined set pressure has not been reached.

[Effect]

With this configuration, after a predetermined pressure increase time has elapsed after voltage is applied to the motor section of the fuel pump, the pressure inside the casing of the fuel pump is compared with a predetermined set pressure, and the detected pressure is determined to have reached the set pressure. If not, you can self-diagnose that a large amount of fuel is leaking into the fuel tank due to a defective hot restart valve seal, foreign matter, etc.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 3. Note that the same components as those in the prior art described above are given the same reference numerals, and their explanations will be omitted.

First, in FIG. 1, reference numeral 21 indicates a pressure sensor for detecting the fuel pressure within the casing 3 of the fuel pump, and the pressure sensor 21 is, for example, a pressure sensing element attached to the upper side of the casing 3. On the other hand, 22 is a fuel temperature sensor that detects the fuel temperature in the fuel tank 1, and the fuel temperature sensor 22 is, for example, a thermistor or the like attached to the outer surface of the lower part of the casing 3.

23 is a motor voltage control device that controls the voltage applied to the motor section 4 of the fuel pump 2, and the motor voltage control device 23 applies a DC voltage V (for example, 12V) to the motor section when the engine switch is turned on. I'm starting to do that. The motor voltage control device 23 is connected to a throttle valve switch, an injection pulse generator, etc., and is controlled to an optimum driving voltage.

Furthermore, 24 indicates a control device that determines a failure of the hot restart valve 9 and outputs a signal to a warning light 25 installed in the driver's seat etc. when the failure occurs.The control device 24 includes, for example, a processing circuit (CPU), a memory It is configured as a microcomputer consisting of circuits (ROM and RAM), input/output circuits (I/F), etc., and its input side is connected to a pressure sensor 21, fuel temperature sensor 22, and motor voltage control device 23, and its output side is a warning signal. It is connected to the light 25. Here, the control device 24
In addition to the program shown in Figure 3, the memory circuit contains a reference temperature T _O = 50℃, a minimum fuel pressure P _O = 1.98Kg/
cm ² , and a data area (none of which is shown) constituting a timer is stored.

The present embodiment is constructed as described above, and its operation will now be described with reference to the program shown in FIG.

First, when the process is started by starting the engine switch, etc., the start of application of the applied voltage V to the motor section 4 is read from the motor voltage control device 23 (step 1), and the fuel F (step 2), and the applied voltage V
The timer is started by starting the application of . Next, in step 3, it is determined whether the fuel temperature T is 50°C or higher, and if it is 50°C or higher, a timer waits to see if 5 seconds have elapsed since the application (step 4).
If the temperature is less than 50°C, wait for 3 seconds after application (step 5). The reason why the waiting time differs depending on the fuel temperature T is that when the temperature T is high, the fuel inside the casing 3 is easily vaporized, and vapor is discharged from the hot restart valve 9, causing the inside of the casing 3 to vaporize easily. This is because a little extra time is required to increase the pressure to a normal pressure state of approximately 2.5 kg/cm ² . Therefore, steps 1 to 5 constitute the boost time measuring means according to this embodiment.

Furthermore, 5 seconds have passed in step 4,
Alternatively, if it is determined in step 5 that 3 seconds have elapsed, the process moves to step 6, reads the pressure P inside the casing 3 of the fuel pump 2 from the pressure sensor 21 (step 6), and sets this pressure P to the preset minimum value. Compare with fuel pressure P _O =1.98Kg/cm ² (Step 7). When it is determined that the fuel pressure is 1.98 kg/cm ² or more, the hot restart valve 9 operates normally, the pressure inside the casing 3 increases to the specified pressure, and fuel is supplied from the check valve 8 to the fuel injection valve. Therefore, the failure determination process ends (step 9). On the other hand, in step 7, the fuel pressure P
is determined to be less than 1.98 Kg/cm ² , the valve body 12 of the hot restart valve 9 has a sealing failure due to swelling etc., and there is also a foreign object (especially, This indicates that the hot restart valve 9 is malfunctioning due to adhesion of gummy material. As a result, in such a case, the warning light 25 is turned on in step 8 to notify the driver, dealer, etc. of the failure. Therefore, step 7 constitutes a specific example of the failure detection means according to this embodiment.

In the example, the reference temperature T _O was set to 50°C, and the pressure increase time after voltage application by the timer was set to different times, 5 seconds and 3 seconds, corresponding to this fuel temperature, while the minimum fuel pressure P _O was set to 1.98 Kg. /cm ² , but these are set as appropriate depending on the model. Further, the warning light 25 may be replaced by other notification means such as a buzzer. Further, although the boosting time measuring means and failure detecting means are described as being realized within the program shown in FIG. 3, it goes without saying that they may be constructed by a hard circuit consisting of a timer mechanism, a comparison circuit, etc. .

〔Effect of the invention〕

The failure detection device for a fuel pump according to the present invention is as described in detail above, and the fuel pressure in the casing reaches a predetermined level after a predetermined pressure increase time has elapsed after applying a motor drive voltage to the motor section of the fuel pump. By comparing whether the set pressure is reached or not,
Since the configuration detects the failure state of the hot restart valve, the state of the hot restart valve can be self-diagnosed at all times, resulting in vehicle running problems due to a decrease in the discharge flow rate from the fuel pump to the fuel injection valve. , it is possible to prevent accidents such as being unable to run, and ensure safety.

[Brief explanation of drawings]

1 to 3 relate to embodiments of the present invention,
Fig. 1 is an overall configuration diagram of the fuel pump used in this embodiment, Fig. 2 is a block diagram showing the circuit configuration, Fig. 3 is a flow chart showing failure detection processing, and Figs. 4 and 5 are related to the conventional technology. 4 is an overall configuration diagram of a fuel pump according to the prior art, and FIG. 5 is a vertical cross-sectional view of a main part showing a hot restart valve. 1...Fuel tank, 2...Fuel pump, 3...
Casing, 4...Motor part, 5...Pump part,
7...Discharge piping, 8...Check valve, 9...
Hot restart valve, 21...pressure sensor,
22...Fuel temperature sensor, 23...Motor voltage control device, 24...Control device, 25...Warning light.

Claims (1)

[Claims] 1 The motor part and pump part are built into the casing,
A fuel pump is equipped with a hot restart valve that discharges fuel through a check valve for maintaining residual pressure and discharges vapor in the casing when the pump section is started, and the fuel pressure inside the casing of the fuel pump is controlled. a pressure detecting means for detecting a pressure; a boosting time measuring means for measuring a pressure increasing time after applying voltage to the motor section of the fuel pump; A fuel pump comprising a failure detection means for comparing whether the detected pressure has reached a predetermined set pressure and detecting a failure of the hot restart valve when the detected pressure has not reached the predetermined set pressure. Failure detection device.