JPH0533730Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel pump pressure boosting characteristic control device that controls the pressure boosting characteristic of a fuel pump that supplies fuel to, for example, an automobile engine.

[Conventional technology]

FIG. 5 shows a fuel injection device including a conventional fuel pump.

In the figure, 1 indicates a fuel tank containing fuel 2, 3 indicates a fuel pump provided in the fuel tank 1, and the fuel pump 3 includes a casing 3A,
A DC motor part 3B as a motor part provided in the casing 3A, a pump part 3C of a Durbin vane type, for example, which is rotationally driven by the DC motor part 3B, and a pump part 3C provided at both upper and lower ends of the casing 3A. It is roughly composed of a suction port 3D and a discharge port 3E. Reference numeral 4 indicates a fuel pipe connected to the discharge port 3E of the fuel pump 3 via a discharge pipe 5, and the tip side of the fuel pipe 4 injects the fuel in the pipe 4 toward an engine (not shown). An injection valve 6 is provided.

Reference numeral 7 indicates a pressure regulator that adjusts the fuel pressure in the fuel pipe 4, and the pressure regulator 7 is configured to return a portion of the fuel 2 discharged from the fuel pump 3 into the fuel pipe 4 as surplus oil and drain it into the pipe 8. Accordingly, the fuel pressure in the fuel pipe 4 is adjusted to, for example, about 0.8 kg/cm ² .
The fuel flowing out from the pressure regulator 7 into the return pipe 8 is sequentially returned into the fuel tank 1. Reference numeral 9 indicates a filter located between the fuel pump 3 and the injection valve 6 and provided in the middle of the fuel pipe 4.

Next, FIG. 6 shows a fuel pump control device, in which numeral 10 is a DC power source consisting of a battery power source, and the DC power source 10 is connected to the high voltage terminal of the DC motor section 3B of the fuel pump 3. Further, the ground terminal of the DC motor section 3B is connected to a voltage control transistor 11 made of a Darlington connection circuit or a power transistor, and a resistor 12 for current detection or overcurrent prevention, and is grounded.

Reference numeral 13 indicates a motor control device, and the motor control device 13 is configured as a microcomputer including a processing circuit (CPU) and a storage circuit (ROM and RAM), and its input side includes an engine switch, an injection pulse generator, and a crank angle sensor. (both not shown), and the output side is connected to the transistor 11 via a transistor control circuit (not shown). Then, the motor control device 13 outputs a voltage control signal to the transistor control circuit such that the average applied voltage between the terminals of the DC motor section 3B becomes, for example, about 9.8V when the engine is idling and about 14V when accelerating, and Voltage control is performed by

Further, when the voltage of the DC power supply 10 is, for example, 9V or less at low temperatures or at the time of starting, the motor control device 13 directly applies this power supply voltage between the terminals of the DC motor section 3B. Particularly when starting at a low temperature, the voltage of the battery (DC power supply 10) is temperature dependent and may drop significantly to 8V or less due to the influence of the ambient temperature. Therefore, the motor control device 1
In this case, 3 applies the voltage from the DC power supply 10 to the DC motor part 3B as it is (value after subtracting the internal voltage drop), and applies as high a voltage as possible to the DC motor part 3B.

In the conventional technology configured as described above, when the engine is started and control is started, a voltage control signal is output from the motor control device 13, the transistor 11 is made conductive, and the DC motor section 3 of the fuel pump 3 is turned on.
A motor driving voltage from the DC power supply 10 is applied to the DC power source 3B to rotate the rotor of the DC motor section 3B.
As a result, the pump section 3C of the fuel pump 3 is driven to rotate, and the fuel 2 in the fuel tank 1 is pumped through the suction port 3D.
while being sucked into the casing 3A from the discharge port 3.
E is supplied to the injection valve 6 via the discharge pipe 5 and the fuel pipe 4. Then, the pressure regulator 7 adjusts the fuel pressure in the fuel pipe 4 to, for example, about 0.8 kg/cm ² and returns excess oil to the fuel tank 1 via the return pipe 8.

[The problem that the idea aims to solve]

By the way, in the above-mentioned conventional technology, fuel pumps manufactured by a plurality of different companies may be used as the fuel pump 3 installed in the fuel tank 1, and one of the fuel pumps 3 is pressurized as shown by the solid line in FIG. In contrast, the other fuel pump may be operated with a boosting characteristic 15 as indicated by a two-dot chain line.

When matching with the engine is performed using a fuel pump 3 with a boost characteristic of 14, when the voltage applied to the DC motor section 3B is about 7V, for example during a cold start, the pump section 3C discharges The pressure is about 0.25Kg/ ^cm2 , and the fuel pressure in the fuel pipe 4 is adjusted by the pressure regulator 7 to 0.8Kg/ ^cm2.
Since the amount of fuel injected from the injection valve 6 is increased as appropriate, the fuel in the fuel pipe 4 is injected from the injection valve 6.

For this reason, in the prior art, when a fuel pump 3 with a boost characteristic 14 is matched with the engine, and a fuel pump with a boost characteristic 15 shown in FIG. 7 is installed in the fuel tank 1 as an alternative delivery, etc. In a fuel pump with boost characteristic 14, the applied voltage is
When the voltage is about 7V, the discharge pressure increases to about 0.8Kg/ ^cm2 , and if fuel is injected from the injector 6 after making an increase correction such as when starting at a low temperature in this state, the air-fuel ratio tends to be rich, resulting in malfunction. Problems have arisen, such as complete combustion and failure to meet emission standards.

The present invention was devised in view of the problems of the prior art described above. Even when fuel pumps with different boost characteristics are used, the present invention provides substantially the same boost voltage by controlling the voltage applied to the motor section. The object of the present invention is to provide a fuel pump pressure boost characteristic control device that can obtain characteristics and solve problems such as emission problems.

[Means to solve the problem]

The features of the configuration adopted by the present invention to solve the above-mentioned problems include a pressure detector that detects the pressure of the fuel discharged by the pump section, and a voltage that is applied to the motor section from the battery to detect the pressure of the fuel discharged by the pump section. determining means for determining whether the pressure detected by the pressure detector when driving the battery satisfies a predetermined pressure-voltage characteristic with respect to the power supply voltage of the battery; and voltage control means for controlling the voltage applied to the motor section based on the determination result of the means.

[Effect]

With the above configuration, the pressure of the fuel discharged by the pump section of the fuel pump is set to a predetermined pressure -
The voltage applied to the motor section can be controlled to match the pressure based on the voltage characteristics.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

In the figure, 21 indicates a fuel pump provided in the fuel tank 1, and the fuel pump 21 has a casing 21, which is similar to the fuel pump 3 described in the prior art.
A, although it is composed of a DC motor section 21B, a pump section 21C, a suction port 21D, a discharge port 21E, etc., their pressure increase characteristics are different, and the fuel pump 3 has a pressure increase characteristic 14 shown by a solid line in FIG. On the other hand, the fuel pump 21 has a pressure increasing characteristic 15 as shown by the two-dot chain line in FIG.
The fuel pump 21 has come to be used in place of the fuel pump 3, as shown in FIGS. 1 and 2, due to alternative delivery or the like.

22 indicates a pressure sensor as a pressure detector provided in the casing 21A of the fuel pump 21;
The pressure sensor 21 is located at the upper end of the casing 21A, and its detection portion faces into the casing 21A. The pressure sensor 21 detects the pressure of the fuel 2 discharged by the pump section 21C by applying voltage to the DC motor section 21B, and outputs the detected pressure P to a motor control device 23, which will be described later. It's summery.

Reference numeral 23 indicates a motor control device configured by a microcomputer, and the motor control device 23
has a DC power supply 10 and a pressure sensor 2 on its input side.
2, etc., and the output side is connected to the transistor 11 via a transistor control circuit (not shown). The motor control device 23 outputs a voltage control signal to the transistor control circuit in the same manner as the motor control device 13 described in the prior art section, and causes the transistor 11 to control the voltage applied between the terminals of the DC motor section 21B. In addition to the functions, the program shown in FIG. 3 is stored in the memory circuit to control the boosting characteristics of the fuel pump 21. Further, the boost map shown in FIG. 4 and the like are stored in the storage area 23A.

The pressure increase characteristic control device for the fuel pump 21 according to this embodiment has the above-mentioned configuration, and its pressure increase characteristic control processing will next be explained with reference to FIGS. 3 and 4.

First, when the processing operation starts by starting the engine, in step 1, the power supply voltage V _B from the DC power supply 10 is read, and this is applied to the fuel pump 2.
1, the pump section 21C is driven by the DC motor section 21B, and the fuel 2 in the fuel tank 1 is discharged into the fuel pipe 4 through the casing 21A by the pump 21C. Then, the discharge pressure of the fuel 2 generated in the casing 21A at this time is detected by the pressure sensor 22, and in step 2, the detected pressure P by the pressure sensor 22 is read, and the process moves to step 3, as shown in FIG. Refer to the boost map and determine the power supply voltage at this time.
Read target pressure P _S based on V _B.

Next, in step 4, the differential pressure ΔP between the detected pressure P and the target pressure P _S is calculated, and the process moves to step 5 to calculate the differential pressure ΔP.
It is determined whether or not the differential pressure △P is greater than zero, and when the determination is "NO", the process moves to step 6, where it is determined whether the differential pressure △P is zero, and thereby the detected pressure P becomes as shown in FIG. It is determined whether or not the predetermined pressure-voltage characteristics shown in FIG. Then, when the determination in step 6 is ``YES'', the detected pressure P matches the target pressure _PS , so the applied voltage at this time is fixed.

Further, when the determination in step 5 is ``YES'', the process moves to step 8, where a voltage control signal is outputted to lower the applied voltage to the DC motor section 21B by a predetermined value, and the transistor 11 is used to lower the applied voltage. Control voltage. That is, since the fuel pump 21 has the pressure increase characteristic 15 shown in FIG. 7, the discharge pressure (detected pressure P) by the pump section 21C is equal to the target pressure P _S of the pressure increase map shown in FIG.
It will be higher than that. Therefore, in step 8, the discharge pressure (detected pressure P) by the pump section 21C is gradually lowered by lowering the voltage applied to the DC motor section 21B by a predetermined value.

Then, the processing operations from step 2 onwards are continued again, and when it is determined in step 6 that the differential pressure ΔP=0, the voltage applied to the DC motor section 21B at this time is fixed in step 7. Also, when the judgment is "NO" in step 6, the applied voltage has become too low, so in step 9, the applied voltage is increased.
The process from step 2 onwards is continued again.

According to this embodiment, even when the fuel pump 21 having the boost characteristic 15 shown in FIG. When _B is about 7V, by lowering the applied voltage to about 5V, the fuel pump 21 with boost characteristic 15 shown in FIG.
The discharge pressure can be reduced to, for example, about 0.25 Kg/cm ² , and a pressure increase characteristic similar to that of the fuel pump 3 with pressure increase characteristic 14 can be obtained.

Therefore, even if the fuel pump 21 with a boost characteristic of 15 is incorporated into the fuel tank 1 while the fuel pump 3 with a boost characteristic of 14 is matched with the engine as described in the prior art, the boost characteristic will not be the same. can be controlled so as to satisfy the pressure increase map shown in FIG. 4, prevent the air-fuel ratio from becoming rich and cause incomplete combustion, and solve the emission problem, among other effects.

In the above embodiment, steps 5 and 6 in the program shown in FIG. 3 are specific examples of the determination means which is a component of the present invention, and steps 7, 8,
9 is a specific example of the voltage control means.

Further, in the embodiment, the pressure sensor 22 as a pressure detector is mounted on the casing 21 of the fuel pump 21.
Although it was stated that it would be provided in A, instead of this,
The pressure sensor 22 may be provided in the middle of the fuel pipe 4 or the like.

As described above in detail, according to the present invention, the voltage applied to the motor of the fuel pump is controlled so as to satisfy a predetermined pressure-voltage characteristic. Therefore, even if a fuel pump with a different pressure-boost characteristic is used, it is possible to obtain a similar pressure-boost characteristic. This makes it possible to prevent incomplete combustion caused by the air-fuel ratio becoming rich, and solves problems such as the inability to meet emission standards.

[Brief explanation of the drawing]

1 to 4 show embodiments of the present invention,
Fig. 1 is an overall configuration diagram of the fuel injection device used in this example, Fig. 2 is a circuit configuration diagram showing the boost characteristic control device of the fuel pump, Fig. 3 is a flow chart showing the boost characteristic control process, and Fig. 4 is An explanatory diagram showing a pressure increase map, FIGS. 5 to 7 show a conventional technique, FIG. 5 is an overall configuration diagram of a fuel injection device used in the conventional technique, and FIG.
The figure is a circuit configuration diagram of the fuel pump control device, and FIG. 7 is a characteristic diagram showing the relationship between applied voltage and discharge pressure. 1... Fuel tank, 2... Fuel, 4... Fuel piping, 6... Injection valve, 7... Pressure regulator, 1
0...DC power supply (battery), 21...Fuel pump, 21A...Casing, 21B...DC motor section, 21C...Pump section, 22...Pressure sensor (pressure detector).

Claims (1)

[Scope of utility model registration request] a motor section that rotates when voltage is applied from a battery; and a motor section that is driven by the motor section;
A fuel pump that includes a pump unit that sucks fuel in a fuel tank and discharges it to the outside, a pressure detector that detects the pressure of the fuel discharged by the pump unit, and a voltage that is applied to the motor unit from the battery. determination for determining whether the pressure detected by the pressure detector when driving the pump section by applying the voltage satisfies a predetermined pressure-voltage characteristic with respect to the power supply voltage of the battery. and voltage control means for controlling the voltage applied to the motor section based on the determination result of the determination means.