JPH04325764A - Pump driving control device - Google Patents

Abstract

PURPOSE:To reduce the cutoff probability of a pump driven by a motor controlled variably in the average applied voltage so as to improve its operating reliability. CONSTITUTION:An engine control device 4, an input signal processing circuit 13 and a driving circuit 14 serving as switching element control means control a switching element 11 intermittently in the duty ratio variable state. The switching element 11 performs the intermittent control (including continuous current application) of an applied current to a pump driving motor 2, and a current detecting circuit 15 detects the average applied current. When an overcurrent flows, an overcurrent judging circuit 16 judges whether the average applied current is the overcurrent and outputs a cutoff signal in the case of the overcurrent. With the input of the cutoff signal, the switching element control means perform the cutoff of the switching element 11 and then resume the driving of the switching element 11 at a duty ratio more than the duty ratio immediately before the cutoff.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump drive control device.

0002

2. Description of the Related Art Japanese Patent Publication No. 62-19582 discloses a drive control device for a fuel pump drive motor. In other words, this drive control device variably controls the magnitude of the average applied voltage to the motor, and also controls the motor when the fuel passage in the fuel pump is clogged with dirt and an overcurrent flows for a predetermined period of time or longer.
This protects the switching elements and motor by cutting off the power to the motor.

0003

[Problems to be Solved by the Invention] However, in the conventional fuel pump control device described above, the average voltage applied to the fuel pump is variably controlled with the intention of saving power during light loads. When 100% voltage is applied, the driving torque to the motor is high, so dirt in the working fluid is less likely to clog the gap between the impeller and the casing, but when the average applied voltage is low, It may become clogged due to a decrease in drive torque.

As a result, the probability of shutting down the pump driven by the motor whose average applied voltage is variably controlled as described above increases, and when the above fuel pump is used, the probability of stopping the internal combustion engine may increase. Possible gender. Of course, in order to reduce the frequency of interruptions, the threshold value for overcurrent detection may be increased, but this poses a problem in that motor lock cannot be detected, resulting in insufficient protection of the switching elements and motor.

The present invention has been made in view of the above-mentioned problems, and aims to improve the operational reliability of a pump driven by a motor whose average applied voltage is variably controlled by reducing the probability of interruption. That is the purpose.

[0006]

[Means for Solving the Problems] As shown in the complaint diagram of FIG. a switching element that intermittently controls a current; a switching element control means that intermittently controls the switching element with a variable duty ratio; a current detection means that detects an average current flowing to the switching element; overcurrent detection means for determining whether or not the average energized current is an overcurrent based on the overcurrent and outputting a cutoff signal for cutting off the switching element when it is determined that there is an overcurrent, the switching element control means The switching device is characterized in that the switching element is cut off when the cutoff signal is input, and then the switching element is driven again at a duty ratio equal to or higher than the duty ratio immediately before the cutoff.

[0007] Here, the switching element control means can drive and control the switching element with a duty ratio of 0 to 1. That is, the switching element can perform cutoff, switching (pulse) driving, and continuous driving. In a preferred embodiment, the overcurrent detection means detects the average applied voltage to the motor, and lowers the threshold for overcurrent determination when the average applied voltage is low.

In a preferred embodiment, the switching element control means performs the re-driving at a duty ratio of one. In a preferred embodiment, the switching element control means prohibits subsequent restart when shutdown and subsequent restart are performed a predetermined number of times.

[0009]

[Operation] The switching element control means intermittently controls the switching element with a variable duty ratio, and the switching element intermittently controls the current flowing to the motor for driving the pump (including continuous energization with a duty ratio of 1), and detects the current. Means detects the average conduction current.

When the pump is clogged with dirt and an overcurrent (so-called restraint current) flows through the switching element, the overcurrent detection means determines whether the detected average current is an overcurrent and detects an overcurrent. Outputs a cutoff signal. The switching element control means shuts off the switching element when the cutoff signal is input, and then re-drives the switching element at a duty ratio equal to or higher than the duty ratio immediately before the cutoff.

[0011]

[Effects of the Invention] As described above, the pump drive control device of the present invention cuts off the switching element at the time of a predetermined overcurrent, and
Thereafter, since the switching element control means is provided to drive the switching element again at a duty ratio higher than the duty ratio immediately before shutoff, the average voltage applied to the pump is low (
In other words, even if the pump becomes clogged with debris (when the pump discharge flow rate is low), the drive is re-driven with a stronger drive torque, so if the debris is small, it can be swept away, reducing the probability of the pump stopping and increasing its operational reliability. can improve sexual performance.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is shown in the block diagram of FIG. This drive control device controls the drive of a motor that drives a fuel pump attached to an internal combustion engine, and includes a pump control device 1 and an engine control device 4. The pump control device 1 includes a switching element 11 , an input signal processing circuit 13 , a drive circuit 14 , a current detection circuit 15 , an overcurrent determination circuit 16 , and a diagnostic output circuit 17 . 12
inputs the output signal of the engine control device 4 to the signal processing circuit 1
Input signal line input to 3, 18 is the diagnostic output circuit 17
The switching element 11 is connected between the power supply 3 and one end of the motor 2, and the other end of the motor 2 is grounded. A wheel diode 19 is connected in parallel with the motor 2. Motor 2 is a DC series motor.

Here, the engine control device 4, input signal processing circuit 13, and drive circuit 14 constitute switching element control means in the present invention, and the current detection circuit 15 constitutes current detection means in the present invention. The current determination circuit 16 constitutes overcurrent detection means in the present invention. Next, details of the drive control device of this embodiment will be explained with reference to FIG.

Input signal line 12 from engine control device 4
is connected to the positive input terminal of the comparator Comp1, and a predetermined voltage VT is supplied to the negative input terminal of the comparator Comp1. The output terminal of the comparator Comp1 is connected to the comparator Comp through an integrating circuit consisting of a resistor R1 and a capacitor C1.
It is connected to the negative input terminal of the comparator Comp3 and the positive input terminal of the comparator Comp3. Negative input terminal of comparator Comp2 and comparator Co
mp3 constitutes a window comparator, and a predetermined voltage VTH is supplied to the positive input terminal of the comparator Comp2.
A predetermined voltage VTL is supplied to the negative input terminal of the comparator Comp3.

The output terminal of the comparator Comp2 is connected to the base of the transistor Q1, the emitter is grounded, and the collector is connected to the output terminal of the constant voltage circuit 20 through resistors R2 and R3. Further, a connection node between the resistor R2 and the resistor R3 is connected to the negative input terminal of the comparator Comp4. The output voltage of the triangular wave generation circuit 21 is applied to the positive input terminal of the comparator Comp4, and a constant voltage is applied to the triangular wave generation circuit 21 as a power supply voltage from the constant voltage circuit 20.

On the other hand, the output terminal of the comparator Comp3 is connected to an overcurrent determination circuit 16, which will be described later, and is also connected to an input terminal of an OR circuit 23 via an inverter 29. An overcurrent determination circuit 16 is connected to the other input terminal of the OR circuit 23.
An output voltage of is applied. The output voltage of the OR circuit 23 is applied to the base of the transistor Q2 via the base current limiting resistor R4.
It is also applied to the overcurrent determination circuit 16.

The output terminal of Comp4 is connected to the base of a voltage amplifying transistor Q3 whose emitter is grounded, and a high voltage is applied to the collector of the transistor Q3 from the booster circuit 22 through a collector resistor R5. The collector of transistor Q3 is connected to both bases of transistors Q4 and Q5 as a complementary emitter follower circuit, the collector of transistor Q4 is connected to the output end of booster circuit 22, and the collector of transistor Q5 is grounded. The emitters of transistors Q4 and Q5 are resistors R
6 to the gate of a switching element 11 consisting of a power MOS transistor.

The drain of the switching element 11 is connected to the power supply 3
The source is connected to one end of the motor 2. The other end of the motor 2 is grounded, and a flyback diode D2 is connected in parallel with the motor 2. Here, the switching element 11 has a double source structure, and the sense terminal 11a, which is a small-area current detection source, is connected to the negative input terminal of the operational amplifier Op1. Further, the positive input terminal of the operational amplifier Op1 is connected to the large area source of the switching element.

The negative input terminal of the operational amplifier Op1 and its output terminal are connected by a feedback resistor R14, and the operational amplifier O
The output terminal of p1 is connected to the negative input terminal of comparator Comp6 via an integrator consisting of resistor R13 and capacitor C3. On the other hand, a voltage dividing circuit formed by connecting a resistor R11 and a resistor R12 in series divides the power supply voltage and outputs the voltage to the comparator Comp6.
The output terminal of the comparator Comp6 is connected to the input terminal of the AND circuit 27.

The other input terminal of the AND circuit 27 has an inverter.
The output voltage of the OR circuit 23 is applied through a resistor 28, and the output terminal of the AND circuit 27 is connected to the base of a transistor Q7 whose emitter is grounded.The collector of the transistor Q7 is connected to the constant voltage circuit 23 through a collector resistor R10. A constant voltage is applied from The collector of transistor Q7 is connected to the anode of diode D1. Resistance R10
The other end is connected to the output of the constant voltage circuit 20, and the cathode of the diode D1 is connected to the negative input terminal of the comparator Comp5. The negative input terminal of comparator Comp5 is connected to capacitor C.
2 to the output terminal of the constant voltage circuit 20, and the resistor R
It is grounded via 9. A predetermined voltage VTR is supplied to the positive input terminal of the comparator Comp5, and its output terminal is connected to the AND
It is connected to the input end of the circuit 25.

The other input terminal of the AND circuit 25 is connected to the output terminal of the above-mentioned comparator Comp3.
The output terminal of 3 is connected to the reset input terminal of an RS flip-flop 24 via an inverter 26. The output of the AND circuit 25 is connected to the set input terminal of the RS flip-flop 24, and the output terminal of the RS flip-flop 24 is connected to the input terminal of the OR circuit 23 and connected to the transistor via the resistor R28. Connected to the base of Q6.

The collector of the emitter-grounded transistor Q6 is connected to the output end of the constant voltage circuit 20 via a collector resistor R7, and outputs a signal voltage to the engine control device 4 via an output signal line 18. Next, the operation of the drive control circuit will be explained. The input signals supplied from the engine control device 4 to the comparator Comp1 include a constantly high level signal (input signal A), a constantly low level signal (input signal C), and a pulse signal with a duty ratio of 50% (
There are three types of input signals B). This input signal is the comparator C
After the waveform is shaped by omp1, the high level is made to match the output voltage (VC) of the constant voltage circuit 20, and the low level is made to match the ground potential. Input signal B is converted to VC/2 by an integrator consisting of resistor R1 and capacitor C1.

The reference voltages VTH and VTL of the comparators Comp2 and Comp3 are set to 0<VTL<VC/2<VTH
If the setting is made so that <VC, the overcurrent determination circuit 16
is not determined to be an overcurrent, that is, the OR circuit 23
When the input signal Vg to the input terminal of is low level, when the input signal A (constantly high level), transistors Q1 and Q2 are both turned off, and when the input signal B (pulse signal), the transistor Q1 turns off. When the input signal C (always low level) is on, transistors Q1 and Q2 are both on.

As a result, the negative input terminal of the comparator Comp4 is VC for input signal A and VC for input signal B ×R3 /(
R2 +R3), becomes 0 at input signal C. On the other hand, when the triangular wave voltage shown in FIG. 3 is applied from the triangular wave generating circuit 21 to the positive input terminal of the comparator Comp4, the comparator Comp4
is high level with input signal A, pulse output with input signal B,
It becomes low level with input signal C. Since the drive circuit 14 is simply a power amplifier circuit, as a result, the switching element 11 is always turned on by the input signal A, and the power supply voltage is almost always applied to the motor 2. Furthermore, the switching element 11 is turned on and off at the same frequency as the triangular wave by the input signal B, and an average applied voltage corresponding to the duty ratio thereof is applied to the motor 2. Furthermore, with the input signal C, the switching element 11 is always turned off, and no voltage is applied to the motor 2.

The source 11b and the sense terminal 11a of the switching element 11 have almost the same potential due to the feedback resistor R14, and a current corresponding to the main current flowing through the source 11b flows from the sense terminal 11a to the feedback resistor R14, and the voltage across both ends of the resistor R14 increases. The potential difference is proportional to the current flowing through the switching element 11. Here, since the negative input terminal of the operational amplifier Op1 is supplied with power through the sense terminal 11a, when the potential difference between both ends of the resistor R14 increases due to an overcurrent, the operational amplifier Op1 is supplied with power through the sense terminal 11a.
The output voltage of p1 decreases. The output voltage of the operational amplifier Op1 is integrated by an integrator including a resistor R13 and a capacitor C3 to become the output voltage Vf of the current detection circuit 15, but this output voltage Vf also decreases due to overcurrent.

FIG. 4 shows the relationship between the average current flowing through the motor 2 and the output voltage Vf. The important point that can be seen from FIG. 4 is that the relationship between the average current flowing through the motor 2 and the output voltage Vf in the case of the constant energization mode (input signal A) and the case of the pulse energization mode (input signal B) is The difference is that The reason for this will be explained below.

In this embodiment, the switching element 11 is used in a source follower mode, and the motor 2 as a source load connected between the source 11b and the ground has a reactance component as well as a resistance component. As a result, in the pulse energization mode, current flows to the flywheel diode D2 and the motor 2 when the switching element 11 is cut off due to the influence of this reactance component. Therefore, the average energizing current of the switching element 11 is smaller in the pulse energizing mode than in the constant energizing mode even if the average energizing current of the motor 2 is the same, and as a result, the resistance R
The voltage drop at 14 becomes smaller. Furthermore, in the pulse energization mode, an average applied voltage corresponding to the duty ratio is applied to the motor 2, but the potential V of the sense terminal 11a
se is equal to this average applied voltage. In the constant energization mode, the potential Vse of the sense terminal 11a is almost equal to the power supply voltage VB, so the output voltage Vf in the pulse energization mode is lower than the output voltage Vf in the constant energization mode, and the motor 2
The slope of with respect to the average conduction current becomes smaller.

Next, the output voltage Vf (low level at the time of overcurrent) is determined by the comparator Comp6 using the reference potential Vm=VB×R1 1 /(R1 1 +R
1 2). That is, comparator Comp6
determines that there is an overcurrent when the output voltage Vf of the voltage detection circuit 15 is lower than the reference potential Vm, and outputs a high level as the overcurrent signal Vs, and otherwise outputs a low level.

The important point here is that the comparator Comp6 is
The problem is that the overcurrent determination threshold current is different between constant energization and pulse energization. For example, as shown in FIG. 4, when the power supply voltage VB is constant, the threshold current is Ith1 during pulse energization, and the threshold current is Ith2 during constant energization. Doing this will have the following effects. That is, when pulse current is applied, a large amount of power is consumed transiently when the current is interrupted due to the influence of the resistor R6 and the reactance of the motor 2 as a source load, and the source current value detected by the potential fluctuation of the source 11a. Switching element 1 compared to
1 has a large calorific value. Therefore, according to this embodiment,
Since the threshold current Ith1 during pulse energization is set to be smaller than the threshold current Ith2 during constant energization, overcurrent detection adapted to the heating state of the switching element 11 is possible.

The next important point is that since the reference potential Vm of the comparator Comp6 is formed by dividing the power supply voltage VB, the overcurrent judgment threshold current can be changed in accordance with fluctuations in the power supply voltage VB. This is what we are doing. In a vehicle power supply, the power supply voltage fluctuates widely, and as the power supply voltage increases, the maximum level of normal current also increases. According to this embodiment, this problem can be solved.

[0031] Although overcurrent can be detected as described above, since the motor 2 has a large current value when starting, it is necessary to avoid misjudging the starting current as an overcurrent, that is, a restraining current when starting. . In this embodiment, the masking time is set to avoid erroneous determination at startup. That is, the OR circuit 23 outputs a low level when the output of the flip-flop 24 is low level (when no overcurrent is detected) with respect to the input signals A and B, and as a result, the input Vx of the AND circuit 27 becomes The signal becomes high level, and the AND circuit 27 is in a state where it can accept the overcurrent signal Vs.

Since the comparator Comp6 outputs the overcurrent judgment signal Vs to the AND circuit 27, which is at a high level when there is an overcurrent and is at a low level when the current is normal, the overcurrent judgment signal Vs is at a low level.
level (normal current), the AND circuit 27 becomes a high level, the transistor Q7 is cut off, and its collector becomes a high level, and the capacitor C2, which forms part of the integration circuit for setting the masking time, has approximately Vc × R
If it is discharged to 9/(R9+R10) and R9>>R10, the output of comparator Comp5 becomes low level,
The flip-flop 24 is reset and the signal voltage Vx becomes high level. As a result, the AND circuit 27, which is a pass gate for the overcurrent determination signal Vs,
is in a state where it can be passed if it is input.

Next, when the overcurrent determination signal Vs output from the comparator Comp6 becomes high level (overcurrent), A
The ND circuit 27 becomes high level, the collector of transistor Q7 becomes low level, diode D1 is cut off, capacitor C2 is charged through resistor R9, and the predetermined value V
When it becomes below TR, the output of comparator Comp5 becomes high level. Here, the time constant of the charging circuit consisting of capacitor C2 and resistor R9 is set to be somewhat longer than the startup time of motor 2, so that the output of comparator Comp5 does not go to low level when motor 2 is started. That's what I do.

When the output of the comparator Comp5 is high level, if the output of the comparator Comp3 is high level (
That is, if input signal A or B is input),
The flip-flop 24 is set, the output terminal Q of the flip-flop 24 becomes a high level signal, and the diagnostic
The sys output Vd is sent to the engine control circuit 4 through the diagnostic output circuit 17. Furthermore, when the output terminal Q of the flip-flop 24 becomes high level, the output of the OR circuit 23 becomes high level (as long as the input signal A or B is input), the output of the inverter 28 becomes low level, and the output of the AND circuit 27 becomes high level. becomes low level, transistor Q7 is cut off, capacitor C2 is discharged, and comparators Comp5,
The output of the AND circuit 25 becomes low level. The S input of the flip-flop 24 becomes low level, but since the R input is also low level, the Q output remains high level.

Furthermore, when the output of the OR circuit 23 becomes high level, the transistor Q2 turns on and the comparator Comp4
The output of the transistor Q3 becomes high level, the transistor Q3 is turned on, and the gate voltage of the switching element 11 becomes low level, so that the switching element 11 is cut off. Due to the above,
The detection of overcurrent and the interruption of the switching element 11 have been described. Next, shutting off and restarting the motor 2 after detecting an overcurrent will be explained with reference to the flowchart of FIG. The engine control circuit 4 includes a microcomputer for engine control, and this microcomputer executes a subroutine (not shown) that outputs any one of input signals A, B, and C depending on the engine load. Further, when the engine is started, the subroutine shown in FIG. 6 is periodically executed.

In this subroutine, first, a counter variable N is reset to 0 (101), it is detected whether or not the diagnosis output Vd is input (102), and the routine waits until the detection is detected. If detected, it is detected whether the count variable N has reached a predetermined set number N (here N=5) (104), and if it has not reached it, input signal C (low level) is sent to the comparator Comp1. supply (106). Then, comparator Comp3 becomes low level, and inverter 2
6, the R input of the flip-flop 24 becomes high level, and the Q output becomes low level. The output of the OR circuit 23 remains at low level.

Next, after a short predetermined time has elapsed (108), the input signal A (high level) is supplied to the comparator Comp1 (
110), adds 1 to the counter variable N and returns it to 102.
Turn on. Then, the switching element 11 is always on,
Motor 2 is driven again. Then, the starting current is detected as an overcurrent, the signal Vs becomes high level, and the capacitor C2 is charged. If the overcurrent continues to be detected even after the predetermined start-up time due to the dust not being removed, the same process as described above will be followed.

When the counter variable reaches Na in step 104, it is assumed that the dust cannot be removed, and an abnormality display is turned on (step 114), the routine is ended, and the motor 2 is kept in a cut-off state. In this way, when the motor 2 is locked, the motor 2 is turned off once due to overcurrent detection, but the engine control device 4 inputs the input signal C and the input signal A in sequence to increase the power level. It generates torque to sweep away clogged debris, reducing the frequency of internal combustion engine shutdowns.

(Other Embodiments) A modification of the input signal processing circuit is shown in FIG. In this embodiment, the engine control device 4
Two input signal lines 12 are directly input to the comparators Comp2 and Comp3, and the voltage applied to the motor 2 is switched by a combination of high level or low level of the two signal lines.

Another embodiment of the overcurrent determination circuit section is shown in FIG. In this embodiment, in addition to the voltage divider circuit (R11, R12) in FIG. 2, a diode D3, constant voltage diode ZD1, resistor R
15 is added. That is, constant voltage diode ZD
1 does not turn on when the power supply voltage VB is low, the resistor R1
It can be considered that the resistor R15 is connected in parallel with 2, and the reference (threshold) voltage Vm can be lowered. On the other hand, if the power supply voltage VB rises and the diode D3 is reverse biased, the reference voltage Vm becomes equal to that of the first embodiment. FIG. 9 shows the relationship between power supply voltage VB and overcurrent determination threshold current Ith. In this way, by making the overcurrent determination threshold current Ith larger than in the first embodiment at a low power supply voltage VB, the characteristics of the current flowing through the motor during normal operation are approximated, and the overcurrent can be detected more accurately. can be detected. As explained above, in each of the above embodiments,
Since the configuration is such that the input signal C is first output from the engine control device 4 to reset the flip-flop 24, and then the input signal A is input again, the restart time can be set arbitrarily until the input signal C is input. There are advantages that can be achieved.

Furthermore, since the switching element control means performs re-driving at a duty ratio of 1, the motor can be restarted with the maximum torque, increasing the probability that dust will be removed. Further, in the above embodiment, since restarting is prohibited after restarting the motor 2 a predetermined number of times, it is possible to prevent harmful effects caused by frequent restarting of the motor 2.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a pump drive control circuit of the present invention.

FIG. 2 is a circuit diagram showing an example of the configuration in FIG. 1;

[Figure 3] Applied voltage waveform diagram to the switching element,

[Figure 4] Characteristic diagram showing the relationship between the motor current and the output voltage of the current detection circuit,

[Figure 5] Overcurrent determination threshold current Ith and power supply voltage VB
Characteristic diagram showing the relationship between

FIG. 6 is a flowchart showing the operation of the engine control device;

[Fig. 7] Circuit diagram showing the deformation mode,

[Fig. 8] A circuit diagram showing a deformed form,

[Figure 9] Overcurrent judgment threshold current I in the circuit of Figure 8
A characteristic diagram showing the relationship between th and power supply voltage VB,

[Explanation of symbols]

2 is a motor, 11 is a switching element, 4 is an engine control device (switching element control means), 13 is an input signal processing circuit (switching element control means), 14 is a drive circuit (switching element control means), and 15 is a current Detection circuit (current detection means), 16 is an overcurrent judgment circuit (overcurrent detection means)

Claims (4)

[Claims] 1. A switching element that is connected in series with a motor that drives a pump and controls intermittently the current flowing to the motor; and switching element control means that controls the switching element intermittently with a variable duty ratio. a current detection means for detecting an average current flowing to the switching element; a current detecting means for determining whether the average current flowing through the switching element is an overcurrent based on the detected average current flowing through the switching element; overcurrent detection means that outputs a cutoff signal for cutting off the element, and the switching element control means cuts off the switching element when the cutoff signal is input, and then adjusts the duty ratio immediately before the cutoff. A pump drive control device characterized in that the switching element control means is driven again at the above duty ratio. 2. The overcurrent detection means detects an average applied voltage to the motor, and lowers a threshold value for determining an overcurrent when the average applied voltage is low. 1. The pump drive control device according to 1. 3. The pump drive control device according to claim 1, wherein said switching element control means performs said re-driving at a duty ratio of 1. 4. The pump drive control device according to claim 1, wherein the switching element control means prohibits subsequent restart when the shutoff and subsequent restart are performed a predetermined number of times.