JP2009156047A - Fuel pump control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel pump control device capable of protecting a coil in terms of temperature without stopping a fuel pump even if the coil as a filter component abnormally generates heat, in a configuration for duty-controlling a driving element for energizing the fuel pump. <P>SOLUTION: A driving circuit 14 carries out 100%-energization to a power MOSFET 6 when a temperature detection signal is outputted from a temperature detection circuit 17 of a hybrid IC 3, recovers a duty when the temperature detection signal is cut in a duty 100%-energized state, and stops the duty 100%-energization to the power MOSFET 6 when a stop command is outputted from a voltage detection circuit 22. This can protect the coil 12 in terms of temperature without stopping the fuel pump 2 even if the external coil as the filter component abnormally generates heat. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel pump control device that supplies, for example, fuel stored in a fuel tank of a vehicle to the outside by a fuel pump.

Conventionally, in a fuel pump control device, a coil is inserted in series with a motor line, and a filter configuration is taken together with a capacitor to reduce noise. For the fuel pump load, there may be abnormalities such as lock and half lock that flow overcurrent greater than the steady current. There is temperature protection when an abnormal current less than protection and overcurrent protection flows.
JP-A-5-332215

  For temperature protection, using the high thermal conductivity of the ceramic substrate on which the drive element and control IC are mounted, the approximate temperature of the drive element and filter component is detected in a batch by the temperature detection means built in the control IC. And protected (see Patent Document 1). This is because the use duty ratio of the fuel pump control is in the range of approximately 60 to 100%, and the filter components can be similarly protected if the heat generation of the drive element on the circuit board is mainly detected.

On the other hand, in recent years, in order to obtain optimum control for fuel pump control, it is necessary to drive even at a low duty of 60% or less, and the temperature of each part is protected under the usage conditions up to such a region. When trying to do so, the heat generation of the coil as the filter component may increase compared to the drive element. For this reason, it is difficult to estimate the temperature with conventional temperature detection using heat conduction, and it is not possible to reliably protect against abnormal heat generation of the coil, for example, with a temperature detection circuit using the VF temperature characteristics of the diode. This causes a problem.
On the other hand, even if it is possible to detect abnormal heat generation of the coil, it is desirable to continue energization to the fuel pump as much as possible because temperature urgency is lower than that of the drive element.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to control the fuel pump even when the coil as the filter part generates heat abnormally in a configuration in which the drive element energized to the fuel pump is duty controlled. An object of the present invention is to provide a fuel pump control device capable of protecting the temperature of a coil without stopping.

  According to the first aspect of the invention, the fuel supply amount can be controlled by duty-controlling the drive current energized to the fuel pump by the control means. Here, when the temperature of the drive element and the coil increases due to energization, the temperature of the substrate having high thermal conductivity that is provided in a heat transfer manner increases, so that the temperature of the substrate detected by the temperature detecting means is increased. When the temperature becomes abnormal, it is desirable to immediately stop energization of the drive element.

However, if the duty for the drive element is reduced in order to suppress the fuel supply amount, the coil temperature may rise above the drive element due to the switching loss of the coil. In such a case, the fuel supply is continued. It is desirable to keep the coil temperature protected.
Therefore, when it is determined that the substrate temperature is abnormal, the control means continues to supply fuel by energizing the drive element with a duty of 100% (direct current). Since the switching loss of the coil is eliminated by such duty 100% energization, the temperature of the coil and thus the substrate is usually lowered. Therefore, when the temperature of the substrate decreases, the duty for the drive element is restored. As a result, it is possible to continue driving the fuel pump while protecting the coil temperature.

  Now, since it is possible to estimate the resistance value of the coil, and thus the approximate temperature, by using the voltage across the coil that is energized with a duty of 100%, it is determined that the coil temperature has risen without the temperature abnormality of the substrate being resolved. In such a case, the coil temperature can be protected by stopping energization of the drive element.

According to the second aspect of the present invention, since the temperature of the coil is directly detected by the temperature sensing element, the accuracy of the temperature protection of the coil can be improved as compared with the configuration in which the temperature is estimated.
According to the third aspect of the present invention, the coil temperature protection can be achieved while executing the control so as to maintain the control close to the current duty control for the fuel pump as much as possible. Can be increased.
According to the invention of claim 4, it is possible to notify the operating state of the temperature protection by the control means to the outside.

(First embodiment)
A first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is an electric circuit diagram showing an electrical configuration of the fuel pump control device. The fuel pump control device 1 is installed in the vicinity of the fuel tank of the vehicle or in the passenger compartment, and drives a fuel pump that supplies fuel stored in the fuel tank to an engine that is an external fuel consuming device. The fuel pump control device 1 is mainly configured by a hybrid IC 3 that controls electric power supplied to the fuel pump 2.

  The hybrid IC 3 includes a control IC (corresponding to control means) 5 that operates in response to a command from the engine ECU 4, a power MOSFET (corresponding to a drive element) 6 that is driven by the control IC 5, and a regenerative diode 7 on a ceramic substrate (not shown). Is mounted and fixed to a radiation fin (not shown) with an adhesive having high thermal conductivity. The control IC 5 is connected to the control terminal FPC and the diagnosis terminal DI. The control terminal FPC is a terminal to which a control signal for the control IC 5 is input from the engine ECU 4. The diagnosis terminal DI is a terminal for diagnosing the control IC 5 by the engine ECU 4.

  The power supply terminal of the control IC 5 is connected to the power supply terminal + B through the coil 8 and is connected to the positive terminal of the vehicle battery 9 through the power supply terminal + B. The ground terminal of the control IC 5 is connected to the earth terminal E, and is connected to the vehicle body through the earth terminal E.

  The drain of the power MOSFET 6 is connected to the power supply line of the hybrid IC 3 via the regenerative diode 7, the source is connected to the ground line of the hybrid IC 3, and the gate is connected to the output terminal of the control IC 5. The positive terminal of the fuel pump 2 is connected to the positive terminal of the vehicle battery 9 through the positive terminal FP + and the power supply terminal + B, and the negative terminal is connected to the negative terminal FP−. Capacitors 10 and 11 are connected between both ends of the coil 8 and the ground terminal E, respectively.

  The drain of the power MOSFET 6 is connected to the negative terminal FP− through a coil 12 as a filter component. A capacitor 13 as a filter component is connected between the negative terminal FP− and the ground terminal E.

  FIG. 2 is an electric circuit diagram showing a configuration related to the configuration of the present invention among the configurations of the control IC 5. The gate of the power MOSFET 6 is connected to the drive circuit 14. The input processing circuit 15 processes the control signal input from the engine ECU 4 through the control terminal FPC to give a normal command to the drive circuit 14 via the switch 16. The drive circuit 14 performs duty control on the power MOSFET 6 in accordance with a normal command given from the input processing circuit 15.

  Basically, the control IC 5 adjusts the electric power supplied to the fuel pump 2 and thus the rotational speed of the fuel pump 2 by performing duty control (PWM control) such as PWM on the power MOSFET 6. Since switching noise due to such duty control occurs and there is a problem of influence on other devices and noise mixing into the radio, noise filter components such as a coil 12 and a capacitor 13 are provided.

The components that generate large heat of the hybrid IC 3 are a power MOSFET 6 and a regenerative diode 7 that are drive elements, and a coil 12 that is a filter component other than the hybrid IC 3.
Regarding the power MOSFET 6 and the regenerative diode 7 which are heat generating components, the control IC 5 uses the high thermal conductivity of the ceramic substrate to detect the temperature of the ceramic substrate, and thus the temperature using the VF temperature characteristic of the diode which detects the temperature of the heat generating component. A detection circuit (corresponding to temperature detection means) 17 is provided, and the temperature detection circuit 17 protects the temperature.

  The coil 12 that is a heat-generating component is fixed to the heat radiating fin with a gel having high thermal conductivity, and the heat radiating fin is provided in heat transfer with the ceramic substrate of the hybrid IC 3, and the power MOSFET 6 and the temperature detection circuit 17 of the control IC 5 are used. Temperature protection is achieved by detecting the temperature together with the regenerative diode 7.

  The temperature detection circuit 17 is configured as follows. As shown in FIG. 2, a series circuit of a plurality of diodes 18 and a resistor 19 is connected between the power supply line and the ground line of the hybrid IC 3, and a common connection point thereof is connected to the inverting input terminal of the comparator 20 so as to be non-inverting. A determination value for determining a temperature abnormality is input to the input terminal. When the temperature proportional voltage input to the inverting input terminal of the comparator 20 rises as the temperature of the diode 18 rises and exceeds the determination value, a temperature detection signal is output from the comparator 20. In the output state of this temperature detection signal, the switch 16 is turned off, the normal command output from the input processing circuit 15 to the drive circuit 14 is cut off, and an abnormal temperature is indicated from the diagnosis circuit (corresponding to the abnormality notification means) 21. A diagnosis signal is output to the engine ECU 4. In this case, hysteresis is set in the comparator 20, and the level of the determination value is lowered by a predetermined level when the temperature detection signal is output.

  By the way, the coil 12 as a filter component is a choke coil configured by winding a copper wire around a toroidal core, and as a heat generation factor, a copper loss due to the resistance of the winding and an iron loss at the core due to a voltage change due to switching. There is. The heat generation of the coil 12 is determined by the sum of the copper loss due to the current value and the iron loss due to the amount of change, and the copper loss is higher as the duty is higher (motor voltage is higher). Although the motor current as a load has a positive characteristic with respect to the voltage, it is considered that the slope is small at a low voltage. For this reason, when the duty is less than the conventionally used duty, as shown in FIG. 4, the heat generation of the coil 12 may increase as compared with the power MOSFET 6, and the temperature of the power MOSFET 6 is estimated by heat conduction through the radiation fin. It becomes difficult. For this reason, there arises a problem that the temperature detection by the temperature detection circuit 17 using the VF temperature characteristic of the diode cannot be reliably protected against abnormal heat generation of the coil 12.

  Therefore, in this embodiment, the control IC 5 is configured as shown in FIG. That is, the abnormality detection signal from the temperature detection circuit 17 is given to the drive circuit 14 as a 100% drive command, and the drive circuit 14 gives the power MOSFET 6 100% when a 100% drive command is given. (DC) is energized. The control IC 5 includes a voltage detection circuit (corresponding to voltage detection means) 22 that detects the voltage across the coil 12.

The voltage detection circuit 22 is configured as follows. Both terminals of the coil 12 are connected to input terminals of the differential amplifier circuit 23 via resistors 24 and 25. The output terminal of the differential amplifier circuit 23 is connected to the inverting input terminal via the resistor 26 and is connected to the non-inverting input terminal of the comparator 28 via the switch 27. The switch 27 is normally turned off and is turned on when an abnormality detection signal is output from the temperature detection circuit 17. A determination value is input to the inverting input terminal of the comparator 28. When the voltage from the differential amplifier circuit 23, that is, the voltage across the coil 12, exceeds the determination value, a stop command is issued from the comparator 28 to the drive circuit 14. Is output. In this case, since the resistance value of the coil 12 increases as the temperature rises, when the coil 12 is energized with a duty of 100%, the voltage across the coil 12 is proportional to the temperature.
When the temperature detection signal is output from the comparator 20 of the temperature detection circuit 17, the diagnosis circuit 21 outputs the abnormal temperature and the change to 100% energization to the engine ECU 4 by the diagnosis signal.

Next, the operation of the fuel pump control device 1 will be described.
When a control signal is given from the engine ECU 4, a normal command is given from the input processing circuit 15 to the drive circuit 14, so that the power MOSFET 6 is duty-controlled by the drive circuit 14 and the fuel pump 2 is rotated at a speed corresponding to the duty. Rotate. Thereby, the fuel stored in the fuel tank is supplied to the engine at the target flow rate.

  When the temperature of the power MOSFET 6 or the coil 12 is normal, the fuel pump 2 is driven by the normal command from the engine ECU 4 as described above. However, when the duty is reduced, the temperature of the coil 12 is increased as shown in FIG. In some cases, the temperature of the coil 12 may be protected. At this time, since a 100% drive command is given from the temperature detection circuit 17 to the drive circuit 14, the drive circuit 14 drives the fuel pump 2 with a duty of 100%. Thereby, the fuel supply to the engine can be continued.

  When such 100% duty driving is performed, loss due to switching of the coil 12 is eliminated, so that the temperature of the coil 12 is lowered. When the temperature proportional voltage applied to the comparator 20 constituting the temperature detection circuit 17 falls below the release determination value as shown in FIG. 3, the temperature detection signal output from the comparator 20 is stopped. Therefore, the switch 16 is turned on. As a result, a normal command is given to the drive circuit 14, so that the drive circuit 14 performs duty control of the power MOSFET 6 with the duty until then.

  However, regardless of the driving with 100% duty as described above, when the voltage across the coil 12 rises, the temperature of the coil 12 rises. Therefore, the comparator 28 constituting the voltage detection circuit 22 When the voltage across the coil 12 supplied through the switch 27 exceeds the determination value, a stop command is given to the drive circuit 14. As a result, the drive circuit 14 stops energization of the power MOSFET 6 with 100% duty, so that the drive of the fuel pump 2 stops and the temperature of the coil 12 decreases. At this time, the voltage across the coil 12 becomes zero. Further, since a stop command is given from the comparator 28 to the diagnosis circuit 21, the diagnosis circuit 21 outputs a diagnosis signal indicating stop to the engine ECU 4.

According to such an embodiment, the drive circuit 14 constituting the control IC 5 energizes the power MOSFET 6 100% when the temperature detection signal (100% drive command) is given from the temperature detection circuit 17, and its energization state. When the temperature detection signal is interrupted, the duty is restored, and when the stop command is given from the voltage detection circuit 22, the energization to the power MOSFET 6 is stopped, so that only the temperature of the ceramic substrate is applied to the drive element. Unlike the conventional configuration in which the energization is stopped, even when the coil 12 as the filter part abnormally generates heat, it is possible to protect the temperature of the coil 12 without stopping the fuel pump 2. Become.
Moreover, by detecting the voltage across the coil 12, it is possible to detect disconnection of the load line.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. 5. The same parts as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. The second embodiment is characterized in that the temperature of the coil 12 as the filter component is directly detected.
A thermosensitive element 31 such as a thermistor is thermally bonded to the coil 12, and the control IC 5 has a temperature detection circuit (corresponding to a second temperature detection means) 32 that directly detects the temperature of the coil 12. It is configured. That is, the operation of the control IC 5 is substantially the same as that of the first embodiment, except that the temperature of the coil 12 is not estimated from the voltage across the coil 12 but directly detected by the temperature detection circuit 32.

According to such an embodiment, since the control IC 5 directly detects the temperature of the coil 12 instead of estimating it, the detection accuracy of the temperature of the coil 12 is increased and the accuracy of temperature protection of the coil 12 is increased. Can do.
As shown in FIG. 5, the power MOSFET 6 may be provided with a temperature sensitive diode 33 as shown in FIG. 5, and the temperature of the power MOSFET 6 may be directly detected and reflected in the control. In this case, since the cost increases, it is desirable to implement according to the required use and usage.
Also, for example, when the temperature of the coil 12 reaches the detected temperature with a low duty, the duty is increased and the presence or absence of a temperature decrease is checked to determine whether to continue driving or stop energization, and at the same time with a diagnosis signal You may make it notify abnormality.

The present invention is not limited to the above embodiment, but can be modified or expanded as follows.
In the configuration in which the temperature sensing element 31 such as the thermistor is thermally transferred to the coil 12 as in the second embodiment, when the control IC 5 is intended to protect the temperature of the coil 12, the duty is increased linearly. Alternatively, when the power MOSFET 6 is energized in a stepwise increased state and the temperature proportional voltage in the temperature detection circuit 17 falls below the release determination value, the temperature detection signal is stopped, and the detected temperature of the coil 12 by the temperature detection circuit 32 is determined. If the value exceeds the value, a stop command may be given to the drive circuit 14. According to such a configuration, it is possible to protect the temperature of the coil 12 while performing control so as to maintain the control close to the current duty control for the fuel pump 2 as much as possible, so that it is compared with the first and second embodiments. And the control performance with respect to the fuel pump 2 at the time of temperature abnormality can be improved.

Instead of the control IC 5, the CPU may perform duty control on the driving element.
The fuel pump 2 may be connected to the fuel pump control device 1 on the high side instead of the low side connection.

1 is an electric circuit diagram of a fuel pump control apparatus showing a first embodiment of the present invention. Electric circuit diagram showing configuration of control IC The figure which shows the state of each signal according to the change of substrate temperature Diagram showing temperature change corresponding to duty FIG. 1 equivalent view showing a second embodiment of the present invention.

Explanation of symbols

  In the drawings, 1 is a fuel pump control device, 2 is a fuel pump, 5 is a control IC (control means), 6 is a power MOSFET (drive element), 12 is a coil, 17 is a temperature detection circuit (temperature detection means), and 21 is A diagnostic circuit (abnormality notification means), 22 is a voltage detection circuit (voltage detection means), 31 is a temperature sensing element, and 32 is a temperature detection circuit (second temperature detection means).

Claims (4)

A driving element mounted on a substrate having high thermal conductivity; a temperature detecting means mounted on the substrate for detecting the temperature of the substrate; and a control means for duty-controlling the driving element; and In the fuel pump control device provided with a coil as a filter component provided between the drive element and the fuel pump,
The control means includes voltage detection means for detecting a voltage across the coil, and determines that the temperature of the substrate detected by the temperature detection means is abnormal in a duty control execution state for the drive element. Energizes the drive element with a duty of 100%, and when it is determined that the temperature abnormality of the substrate has been eliminated in the energized state, the duty is restored, and the voltage detection means by the voltage detection means in a state where the temperature abnormality of the substrate is not eliminated A fuel pump control device that stops energization of the drive element when it is determined that the temperature of the coil is rising based on the voltage across the coil. A driving element mounted on a substrate having high thermal conductivity; a temperature detecting means mounted on the substrate for detecting the temperature of the substrate; and a control means for duty-controlling the driving element; and In the fuel pump control device provided with a coil as a filter component provided between the drive element and the fuel pump,
A temperature-sensitive element provided in a heat transfer manner on the coil;
The control means includes second temperature detection means for detecting the temperature of the coil by the temperature sensing element, and the temperature of the substrate detected by the temperature detection means in an execution state of duty control with respect to the drive element is abnormal. When it is determined that the drive element is energized with a duty of 100%, and when it is determined that the temperature abnormality of the substrate has been resolved in the energized state, the duty is restored, and the temperature abnormality of the substrate is not resolved The fuel pump control device according to claim 1, wherein when it is determined that the temperature of the coil is rising based on the temperature of the coil by the second temperature detecting means, the energization to the drive element is stopped. A driving element mounted on a substrate having high thermal conductivity; a temperature detecting means mounted on the substrate for detecting the temperature of the substrate; and a control means for duty-controlling the driving element; and In the fuel pump control device provided with a coil as a filter component provided between the drive element and the fuel pump,
A temperature-sensitive element provided in a heat transfer manner on the coil;
The control means includes second temperature detection means for detecting the temperature of the coil by the temperature sensing element, and the temperature of the substrate detected by the temperature detection means in an execution state of duty control with respect to the drive element is abnormal. When it is determined that the drive element is energized in a state where the duty is increased linearly or stepwise, the duty is restored when it is determined that the temperature abnormality of the substrate has been eliminated in the energized state. When it is determined that the temperature of the coil is rising based on the temperature of the coil by the second temperature detection means in a state where the temperature abnormality of the substrate is not eliminated, the energization to the drive element is stopped. Fuel pump control device.   4. The control means according to claim 1, further comprising an abnormality notification means for outputting to the outside that the drive circuit has been energized 100% or has been de-energized. Fuel pump control device.

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