JP2012237321A - Fuel pump drive control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a noise of an electrically operated fuel pump for a vehicle by the electrically operated fuel pump where a fuel pressure can be changed.SOLUTION: The fuel pump drive controller of an internal combustion engine supplies the fuel to the fuel jetting valve 9 of an internal combustion engine by the electrically operated fuel pump 4 driven by a PWM signal where a driving frequency can be changed, and variably controls the fuel pressure by adjusting the energizing current flow duty ratio of the fuel pump 4, wherein the pump noise is controlled by setting the drive frequency f at higher ones, the lower, at least either the engine rotational speed or the vehicle speed is, and by more increasing the frequency f than an audible upper limit frequency or by the vicinity thereof in a low speed area where the noise from the engine driving noise or from the vehicle body is lower.

Description

  In the present invention, fuel is supplied to a fuel injection valve by an electric fuel pump driven by a PWM (pulse width modulation) signal whose drive frequency is variable, and the fuel pressure is varied by adjusting the drive amount of the fuel pump. The present invention relates to an internal combustion engine fuel pump drive control device.

  Japanese Patent Application Laid-Open No. 2003-259542 discloses a fuel pump drive control device for an internal combustion engine that controls an amount of fuel supplied to a fuel injection valve by an electric fuel pump that is driven and controlled by a PWM signal. There is disclosed a technique for suppressing fuel pump drive noise by setting the fuel pump drive frequency to a high frequency exceeding the audible range in a low discharge amount region having a smaller pulse width, that is, a ratio of on-time.

Japanese Patent Laid-Open No. 2008-2332099

  By the way, in the fuel pump drive control device that variably controls the fuel pressure by increasing the duty ratio of the PWM signal according to the engine operating state, the noise of the fuel pump becomes a problem. There is a case where the discharge amount of the fuel pump is increased during traveling.

  However, when the driving frequency setting method disclosed in Patent Document 1 is applied, the driving frequency decreases due to an increase in the discharge amount of the fuel pump, that is, an increase in the duty ratio of the PWM signal. As a result, there was a problem that the operation sound of the fuel pump became conspicuous.

  In order to solve such a conventional problem, an object of the present invention is to suppress pump noise even in an internal combustion engine that supplies fuel to a fuel injection valve by an electric fuel pump capable of changing fuel pressure.

For this reason, the present invention
A fuel pump drive for an internal combustion engine in which fuel is supplied to a fuel injection valve by an electric fuel pump driven by a PWM signal whose drive frequency is variable, and the fuel pressure is variably controlled by adjusting the drive amount of the fuel pump In the control device, the drive frequency is set as follows.

When at least one of the engine rotational speed and the vehicle speed is in the low speed range, the drive frequency is increased as compared with the high speed range.
Alternatively, the drive frequency is changed to a large value under the condition of increasing the fuel pressure with a low load or the like.

  Even when the fuel discharge amount is increased in the operation region where the discharge amount is low, the pump noise can be suppressed by increasing the drive frequency.

The figure which shows the fuel supply apparatus of the engine for vehicles provided with the fuel pump drive control apparatus which concerns on embodiment Flowchart of drive frequency setting according to the first embodiment A diagram showing an example in which the drive frequency f is set to decrease proportionally with an increase in engine rotation speed A diagram showing an example in which the decrease amount Δf of the drive frequency f is set to be larger as the engine speed increases. A diagram showing an example in which a reduction amount Δf of the drive frequency f in the middle speed region of the engine rotation is set to be large. Flowchart of drive frequency setting according to the second embodiment A diagram showing an example in which the drive frequency f is set to decrease proportionally with an increase in vehicle speed A diagram showing an example in which the decrease amount Δf of the drive frequency f is set to be larger as the vehicle speed increases. A diagram showing an example in which the amount of decrease Δf of the drive frequency f in the medium speed range is set to be large. Flowchart of drive frequency setting according to the third embodiment A diagram showing an example in which the drive frequency f is set so as to decrease in proportion to the increase in engine speed and vehicle speed. A diagram showing an example in which a decrease amount Δf of the drive frequency f is set to be larger as the engine speed and the vehicle speed are increased. A diagram showing an example in which a reduction amount Δf of the drive frequency f in the medium speed range of the engine rotation speed and the vehicle speed is set large. Flowchart of drive frequency setting according to the fourth embodiment Flowchart of drive frequency setting according to the fifth embodiment Flowchart of drive frequency setting according to the sixth embodiment The diagram which showed the example which changes and sets a part of flow of FIGS. 14-16 Flowchart of drive frequency setting according to the seventh embodiment Flowchart of drive frequency setting according to the eighth embodiment Flowchart of drive frequency setting according to the ninth embodiment Flowchart for setting drive frequency according to the tenth embodiment

Embodiments of the present invention will be described below.
FIG. 1 is a diagram illustrating a fuel supply device for a vehicle engine including a fuel pump drive control device according to an embodiment.

In FIG. 1, a fuel tank 1 is a tank for storing fuel (gasoline) of an engine (internal combustion engine) 10 and is disposed, for example, under a rear seat of a vehicle.
The fuel tank 1 is provided with a fuel filler opening 3 that is closed by a fuel filler cap 2, and the fuel filler cap 2 is removed to replenish fuel from the fuel filler inlet 3.

An electric fuel pump 4 is installed in the fuel tank 1 by a bracket (not shown).
The fuel pump 4 is an electric pump of, for example, a turbine type that sucks gasoline in the fuel tank 1 from a suction port and discharges it from the discharge port, and one end of a fuel pipe 5a is connected to the discharge port.

  The other end of the fuel pipe 5a passes a fuel flow from the fuel pump 4 toward a fuel injection valve 9 to be described later, and a check valve that blocks a flow (back flow) from the fuel injection valve 9 toward the fuel pump 4. 7 inlet side is connected.

The fuel pipe 5a, the fuel pipe 5b, and the fuel gallery pipe 8 form a fuel supply passage from the fuel pump 4 toward the fuel injection valve 9.
The fuel gallery pipe 8 is provided with the same number of injection valve connection portions 8a as the number of cylinders (4 cylinders in the present embodiment) along the extending direction, and each injection valve connection portion 8a includes a fuel injection valve. Nine fuel intakes are connected to each other.

  The fuel injection valve 9 is an electromagnetic fuel injection valve in which when a magnetic attractive force is generated by energization of an electromagnetic coil, a valve body biased in a valve closing direction by a spring lifts and injects fuel.

The fuel injection valve 9 is installed at each intake port portion of each cylinder of the engine 10 and injects fuel into each cylinder.
Further, a relief pipe 12 is provided for communicating the inside of the fuel gallery pipe 8 and the inside of the fuel tank 1, and a relief valve 13 is interposed in the middle of the relief pipe 12.

  The relief valve 13 is urged in the valve closing direction by an elastic body, and is a mechanical check valve that relieves the fuel in the fuel gallery pipe 8 into the fuel tank 1, and the fuel power in the fuel gallery pipe 8. Is provided to prevent the pressure from becoming larger than the valve opening pressure (allowable upper limit pressure).

  An electronic control unit (ECU) 11 incorporating a microcomputer individually outputs a valve opening control pulse signal to each of the fuel injection valves 9 to control the fuel injection amount and injection timing of each fuel injection valve 9. .

Detection signals from various sensors are input to the electronic control unit 11.
The various sensors include an air flow meter 21 that detects the intake air flow rate of the engine 10, a crank angle sensor 22 that outputs a detection signal for each predetermined crank angle position, a water temperature sensor 23 that detects a cooling water temperature Tw of the engine 10, A fuel pressure sensor 24 for detecting the pressure of the fuel in the fuel gallery pipe 8, a fuel temperature sensor 25 for detecting the temperature of the fuel in the fuel gallery pipe 8, a vehicle speed sensor 26 for detecting the vehicle speed, and the like are provided.

  Then, the electronic control unit 11 sets the injection pulse width corresponding to the amount of fuel that can form the target air-fuel ratio mixture from the air flow meter 21, the crank angle sensor 22, the water temperature sensor 23, the air-fuel ratio sensor 26, and the like. And the valve opening control pulse signal having the injection pulse width is output to each fuel injection valve 9. The electronic control unit (ECU) 11 performs other engine control (ignition timing, throttle control) and the like.

  The pump control unit (PCU) 14 adjusts the fuel discharge amount of the fuel pump 4 by changing the drive current (pump drive amount) by controlling the duty ratio of the PWM signal to the fuel pump 4 to adjust the fuel discharge amount. Control the pressure. The relief valve 13 may be configured by an electromagnetically driven valve, and the fuel pressure may be adjusted by using a control for adjusting the fuel outflow amount from the relief valve 13 by duty control.

Here, the energization duty ratio is controlled by feedback control so that the actual fuel pressure detected by the fuel pressure sensor 24 approaches the target fuel pressure.
In the feedback control, the fuel pump 4 needs to discharge the amount of fuel delivered from the fuel gallery pipe 8 to the fuel injection valve 9, that is, the amount of fuel commensurate with the fuel injection amount from the fuel injection valve 9. The energization duty ratio increases as the injection amount increases, and when the target fuel pressure is high, the fuel discharge amount is increased to increase the fuel pressure, so that the energization duty ratio further increases as the fuel pressure increases. Set to increase.

  Further, the drive circuit of the fuel pump 4 built in the pump control unit 14 is configured so that the drive frequency of the PWM signal (frequency at which the on-duty is output) can also be changed.

  A control unit that calculates the duty ratio and drive frequency of the fuel pump 4 and outputs an instruction value to the drive circuit may be built in the electronic control unit 11 or may be built in the pump control unit 14. Good.

  Here, the control unit of the fuel pump built in the electronic control unit 11 or the pump control unit 14 variably sets the drive frequency in the duty control of the fuel pump 4.

  In order to suppress the heat generation from the drive circuit of the fuel pump 4 built in the pump control unit 14, the drive frequency for duty control may be lowered. However, if the drive frequency is lowered, the frequency of the pump drive sound enters the human audible range and the pump noise increases.

Therefore, in the following embodiment, the drive frequency is set so that the problem of pump noise can be avoided while suppressing heat generation from the drive circuit.
FIG. 2 shows a flow of drive frequency setting according to the first embodiment.

  In the present embodiment, the drive frequency f of the PWM signal output to the fuel pump 4 is set based on the engine speed in step S101. Specifically, as shown in the figure, the drive frequency f is set to increase as the engine speed decreases.

  Here, since the generated sound (particularly vibration sound) from the engine is small when the engine rotation speed is low, when the driving frequency is low, the pump driving sound is felt loud, and pump noise giving unpleasant feeling is generated.

  Therefore, in this embodiment, as the engine rotation speed is low and the generated sound from the engine decreases, does the drive frequency f of the fuel pump 4 become larger than the audible upper limit frequency (15,000 Hz to 20000 Hz depending on individual differences)? Alternatively, the pump noise can be suppressed by increasing the frequency to near the audible upper limit frequency.

  Further, even if the drive frequency f of the fuel pump 4 is lowered and the pump drive sound is increased as the engine speed increases, the pump drive sound is drowned out due to an increase in engine noise. By reducing the temperature, heat generation of the drive circuit can be suppressed, miniaturization of the drive circuit can be promoted, and fuel consumption can be reduced by reducing power consumption.

  Here, when the engine speed is low, such as when the engine temperature (water temperature) is low and when the engine is running at low speed, the fuel pressure can be increased to promote atomization of the fuel injected from the fuel injection valve 9. . In this case, the energization duty ratio (the driving amount of the fuel pump 4) increases as the fuel pressure increases, but the drive frequency f is maintained at a higher frequency as the engine speed is lower regardless of the increase in the energization duty ratio. Therefore, the pump noise suppression effect can be ensured.

  In addition, when the engine is running at low speed and high load, such as when starting, the energization duty ratio increases as the required fuel discharge amount of the fuel pump 4 increases. In this case, the drive frequency f is not related to the increase in the energization duty ratio. Since the high frequency is maintained, the pump noise suppression effect can be ensured.

The drive frequency characteristic shown in step S101 is set to be switched stepwise with respect to the engine speed, but may be set to change steplessly.
For example, FIG. 3 shows an example in which the drive frequency f is set to decrease proportionally with respect to an increase in the engine rotation speed, and FIG. 4 shows that the decrease amount Δf of the drive frequency f is set larger as the engine rotation speed increases. FIG. 5 shows an example in which the reduction amount Δf of the drive frequency f in the middle speed region of the engine rotation is set large. As shown in FIGS. 4 and 5, the increase Δf in the drive frequency f in the medium speed range is caused by a sudden increase in friction between the tire and the road surface, which causes a sudden increase in road noise and drown out pump noise. Considering that it is easy to get.

FIG. 6 shows a drive frequency setting flow according to the second embodiment. In step S201, the drive frequency is set to increase as the vehicle speed decreases.
Here, when the vehicle speed is low, noise from the vehicle body (especially, road noise due to friction between the tire and the road surface) is small. Therefore, when the driving frequency f of the fuel pump 4 is low, the pump driving sound is felt loud. Unpleasant noise.

  Therefore, in the present embodiment, as the vehicle speed is low and the noise from the vehicle body decreases, the drive frequency f of the fuel pump 4 is set to be larger and deviated from the audible range or increased to near the audible limit, thereby reducing the pump noise. Can be suppressed.

  Further, even if the drive frequency f of the fuel pump 4 is reduced and the pump drive sound is increased as the vehicle speed increases, the pump drive sound is drowned out due to an increase in noise from the vehicle body, so that it is less likely to be felt as noise. By reducing f, heat generation in the drive circuit can be suppressed, so that the drive circuit can be reduced in size and the fuel consumption can be reduced by reducing power consumption.

  Furthermore, even when the engine output is large and the energization duty ratio increases as the required fuel amount increases even at low vehicle speeds, such as when traveling on an uphill, the driving frequency f is set to a high frequency, so that pump noise can be suppressed.

The drive frequency f of the fuel pump 4 illustrated in step S201 is set to be switched stepwise with respect to the vehicle speed, but may be set to change steplessly.
For example, FIG. 7 shows an example in which the drive frequency f is set to decrease proportionally with respect to an increase in the vehicle speed, and FIG. 8 shows an example in which the decrease amount Δf of the drive frequency f is set larger as the vehicle speed increases. 9 shows an example in which the reduction amount Δf of the drive frequency f in the middle speed range of the vehicle speed is set large. As shown in FIGS. 8 and 9, increasing the reduction amount Δf of the drive frequency f in the middle speed range of the vehicle speed causes the friction between the tire and the road surface to suddenly increase, the road noise increases rapidly, and the pump noise increases. It takes into account that it is easy to be worn out.

FIG. 10 shows a flow of setting the drive frequency according to the third embodiment. In step S301, the drive frequency f is set to be larger as the engine speed and the vehicle speed are lower (A>B>). C).

  In the present embodiment, the smaller the external noise, which is the sum of the engine noise and the noise from the vehicle body, can suppress the pump noise by increasing the drive frequency f of the fuel pump 4, while the external noise is large and the pump noise is drowned out. Accordingly, the drive frequency f can be reduced to suppress the heat generation from the drive circuit, thereby promoting the downsizing of the drive circuit and reducing the power consumption.

  Even when the fuel pressure is increased due to fuel atomization as described above, or when the energization duty ratio is increased when the required fuel quantity is large even when the engine or vehicle speed is low, such as when starting or climbing, the drive frequency is Since the high frequency is set when the external noise is small irrespective of the energization duty ratio, the pump noise can be suppressed.

  Also in this embodiment, the characteristics of the drive frequency f illustrated in step S301 are set to be switched stepwise with respect to the engine speed and the vehicle speed, but may be set to change steplessly.

  For example, FIG. 11 shows an example in which the drive frequency f is set to decrease in proportion to the increase in the engine speed and the vehicle speed, and FIG. 12 shows a decrease amount of the drive frequency f as the engine speed and the vehicle speed increase. FIG. 13 shows an example in which Δf is set to a large value. FIG. 13 shows a decrease amount of the driving frequency f in the middle speed range in consideration of the sudden increase in road noise in the middle speed range of the engine speed and the vehicle speed as described above. An example in which Δf is set large is shown.

  In the fourth to sixth embodiments shown in FIG. 14 to FIG. 16, the first drive frequency having a characteristic that increases as the drive amount (energization duty ratio) of the fuel pump decreases as in the prior art is set. A dynamic frequency having the same characteristics as in the third embodiment is set as the second drive frequency, and the larger one of these two drive frequencies is selected.

  That is, in steps S110, 210, and 310 of FIGS. 14 to 16, the first drive frequency X is set based on the energization duty ratio of the PWM signal. Specifically, as shown in the figure, the first drive frequency X is set to increase as the energization duty ratio decreases.

  14 to 16, steps S120, 220, and 320 are the same as steps S101, S201, and S301 of FIGS. 2, 6, and 10, respectively, and the engine speed, the vehicle speed, or the engine speed and the vehicle speed. The second drive frequency Y is set based on the above.

In steps S130, 230, and 330, the first drive frequency X and the second drive frequency Y are compared, and the larger one is selected and set as the final drive frequency f of the fuel pump.
In this way, when the first drive frequency X set according to the energization duty ratio is smaller than the second drive frequency Y, the second drive frequency Y is selected, so that the engine speed and the vehicle speed are low. In some cases, pump noise can be suppressed by the second drive frequency Y set to a high frequency.

  Further, the first drive frequency X is set so as to increase as the energization duty ratio decreases as described above. For example, if the engine speed is high, such as during deceleration, but the load is low, the engine drive sound is reduced by the amount of combustion noise that is lower than when the load is high. It stands out.

  In such a case, the first drive frequency X, in which the fuel discharge amount of the fuel pump is small and increases as the energization duty ratio decreases, exceeds the second drive frequency Y that is set based on the engine speed and the vehicle speed. The pump noise can be suppressed by being selected.

  Also, as the energization duty ratio decreases, the energization off time in the energization cycle increases and current fluctuations (pulsations) are likely to occur. Therefore, the first drive frequency X increases as the energization duty decreases, By setting the interval to be short, fluctuations in the current can be suppressed, and as a result, there is an effect of improving stable fuel pump discharge performance and further fuel injection controllability from the fuel injection valve, and the first drive frequency X is the second. This effect can be ensured when the driving frequency Y is selected to be higher.

  Further, the setting of the second drive frequency Y in steps S120, 220, and 320 of FIGS. 14 to 16 is performed according to the drive frequencies set in FIGS. 3 to 5, FIGS. 7 to 9, and FIGS. It may be used.

  Also, in the high speed range of the engine rotation speed and the vehicle speed, the influence of the pump noise is small, so the second drive frequency Y is not set (Y = 0) and the first drive frequency X is selected and the energization duty ratio is large. Alternatively, the drive frequency may be reduced to suppress the heat generation of the drive circuit.

  On the other hand, in steps S110, 210, and 310 of FIGS. 14 to 16, the first drive frequency X is set based on the energization duty. However, the engine load is a parameter correlated with the drive amount (fuel discharge amount) of the fuel pump. For example, as shown in FIG. 17, the fuel flow rate (= the fuel injection amount from the fuel injection valve × the engine rotational speed) or the intake air flow rate may be used, and the first drive frequency X may be set to increase as these are smaller. Good.

FIG. 18 shows a flow of drive frequency setting according to the seventh embodiment.
In step S401, as in the above embodiment, the first drive frequency X is set so as to increase as the energization duty ratio decreases. Alternatively, the first drive frequency X may be set based on the engine load in FIG.

  In step S402, it is determined whether or not the engine temperature (engine water temperature) Tw is a low water temperature equal to or lower than a predetermined value Tw0. The predetermined value Tw0 is a warm-up completion determination temperature, and is set in a range of 60 ° C to 90 ° C.

  When it is determined in step S402 that the water temperature is low (cooling time), it is determined in step S403 whether the engine load is in a low load region (including start time and idling operation) of a predetermined value Te0 or less. 9 is determined based on whether the fuel flow rate from 9 or the amount of intake air is less than a predetermined value.

  When it is determined in step S403 that the load is low, that is, when starting at a low temperature or during idling, the process proceeds to step S404, and atomization of the fuel injected from the fuel injection valve 9 is performed to promote fuel vaporization. In order to promote the fuel pressure, the energization duty ratio of the PWM signal of the fuel pump 4 is increased to increase the fuel pressure.

  In step S405, when the energization duty ratio is increased and the fuel pressure is increased as described above, the PWM signal drive frequency f is set to the first drive frequency set for the same energization duty ratio in step S401. The third drive frequency Z is set to a value higher than X and set to a value (a value higher than the audible range or near the audible limit) that can suppress pump noise.

  In addition to the low water temperature, the outside air temperature Ta is detected, and the generation of vapor in the fuel pipe is suppressed at the start (steps S405 and S406) when the outside air temperature Ta is equal to or higher than the predetermined temperature Ta0. Similarly, the energization duty ratio is increased to increase the fuel pressure, and the drive frequency f is switched to the third drive frequency Z set to a value higher than the first drive frequency X (step S404). Here, the predetermined temperature Ta0 is set as an upper limit temperature at which vapor generation is allowed. Further, the fuel temperature may be determined instead of the outside air temperature.

  In this way, when the energization duty ratio increases due to an increase in fuel pressure in the engine low speed region such as during start-up or idle operation, the set value of the first drive frequency X is increased due to the increase in the energization duty ratio. Although reduced, the pump noise can be suppressed by switching to the second drive frequency Y. In other cases, the first drive frequency X is set, and pump noise can be suppressed while suppressing heat generation.

  As in the above embodiments, the amount of heat generation increases when the drive amount (energization duty ratio) of the fuel pump is increased and the drive frequency is increased. Therefore, a configuration may be added in which the drive frequency is limited based on the heat generation amount so that the heat generation amount does not become too large.

Hereinafter, an embodiment in which the drive frequency is limited based on the heat generation amount will be described.
FIG. 19 shows a drive frequency setting flow according to the eighth embodiment.
In step S501, the basic drive frequency f0 (the finally set drive frequency f in each embodiment) is set in the same manner as in any of the above embodiments.

In step S502, the current heat generation amount is calculated based on the current drive frequency and the energization duty ratio. Specifically, the current calorific value is calculated by the following equation for each calculation cycle.
Current calorific value = previous calorific value + new calorific value-heat dissipation during the calculation cycle ... (1)
Here, the new heat generation amount is calculated by searching from the illustrated characteristic map based on, for example, the drive frequency and the energization duty ratio. The characteristics of the map are such that the heat generation amount is set to a larger value as the drive frequency is larger and as the energization duty ratio is larger.

In addition, the heat release amount is simply constant. However, the lower the temperature around the drive circuit (which may be roughly estimated by the engine temperature or the like), the higher the value may be set.
Note that at the beginning of the calculation, the drive frequency and energization duty ratio used for calculating a new heat generation amount are set to the final values set as in the above embodiments, the previous heat generation amount and heat release amount are set to 0, and the current Calculate calorific value.

At step S503, based on the current heating value calculated above, it sets an upper limit driving frequency f _L for suppressing excessive heat generation. For example, based on a map characteristic shown, it is set to a small value the maximum driving frequency f _L as the current heating value increases.

In step S504 setting, the basic driving frequency f0 set by the step S501, is compared with the upper driving frequency f _L set in step S503, as the driving frequency f of the final fuel pump by selecting a smaller To do.

FIG. 20 shows a ninth embodiment in which a new calorific value calculation method is changed when calculating the calorific value based on the equation (1) in step S502 in the above embodiment.
In the present embodiment, a current sensor for detecting the drive current value ip of the fuel pump is provided, and the current value ip increases based on the pump drive current value ip detected by the current sensor as shown in step S602. Accordingly, the new heat generation amount is set to a large value. Steps S601, S603, and S604 are the same as steps S501, S503, and S504 in FIG.

As described above, according to the seventh and eighth embodiments, it is possible to suppress the heat generation from the fuel pump driving circuit by limiting the increase in the driving frequency f by the upper limit driving frequency f _L , and to promote downsizing of the driving circuit. By reducing power consumption, fuel savings can be saved. Further, by limiting by the upper limit driving frequency set while calculating the heat generation amount, the driving frequency f can be increased to near the limit, and the pump noise suppression effect can be enhanced.

Figure 21 is a setting of the upper driving frequency f _L corresponding to the calorific value, showing a tenth embodiment described more simply.
In the present embodiment, as in the eighth embodiment, a current sensor for detecting the driving current value ip of the fuel pump is provided, and in step S702, the upper limit driving frequency f _L is set based on the pump driving current value detected by the current sensor. Set. As shown, the pump drive current value ip is so correlated with the amount of heat generated from the drive circuit, an upper limit driving frequency f _L is set to decrease as the pump drive current value ip is increased.

Steps S701 and S703 are the same as steps S501 and S504 in FIG.
In addition, although not shown, in the embodiment in which the first drive frequency X and the second drive frequency Y are set more simply and the larger one is selected, the second drive frequency Y is continuously selected for a predetermined time or more. In this case, the first drive frequency X may be forcibly selected.

Further, technical ideas other than the claims that can be grasped from the above embodiment will be described together with the effects thereof.
(A) An internal combustion engine that supplies fuel to a fuel injection valve by an electric fuel pump driven by a PWM signal whose drive frequency is variable, and adjusts the drive amount of the fuel pump to variably control the fuel pressure. A fuel pump drive control device comprising:
First driving frequency setting means for setting the driving frequency to be larger as the driving amount of the fuel pump is smaller;
When the start condition where the outside air temperature is equal to or higher than the predetermined temperature is satisfied, the fuel pressure is increased compared to when the start condition is not satisfied, and the drive frequency is changed to a third drive frequency higher than the first drive frequency set by the drive frequency setting means. Third driving frequency setting means for setting
When this configuration is adopted, it is possible to suppress the occurrence of vapor in the fuel pipe by increasing the fuel pressure while increasing the energization duty ratio for increasing the fuel pressure. The set value of the first drive frequency X decreases with the increase of the energization duty ratio, but the pump noise can be suppressed by switching to the second drive frequency Y. In other cases, the first drive frequency X is set, and pump noise can be suppressed while suppressing heat generation.

(B) A fuel pump drive control device for an internal combustion engine according to claim 5,
The upper limit drive frequency setting means sets the upper limit drive frequency while estimating the amount of heat generation based on the energization duty ratio of the PWM signal and the drive frequency.
With this configuration, the heat generation amount can be estimated well and the upper limit drive frequency can be set with high accuracy.

(C) A fuel pump drive control device for an internal combustion engine according to claim 5,
The upper limit drive frequency setting means sets an upper limit drive frequency according to the amount of heat generation based on the drive current value of the fuel pump.

  With this configuration, the upper limit drive frequency can be easily set based on the current value.

DESCRIPTION OF SYMBOLS 1 ... Fuel tank, 4 ... Fuel pump, 5a, 5b ... Fuel pipe, 7 ... Check valve, 8 ... Fuel gallery pipe, 9 ... Fuel injection valve, 10 ... Internal combustion engine, 11 ... Electronic control unit, 12 ... Relief pipe , 13 ... Relief valve, 14 ... Pump control unit, 24 ... Fuel pressure sensor, 26 ... Current sensor

Claims (5)

A fuel pump drive for an internal combustion engine in which fuel is supplied to a fuel injection valve by an electric fuel pump driven by a PWM signal whose drive frequency is variable, and the fuel pressure is variably controlled by adjusting the drive amount of the fuel pump A control device,
A fuel pump drive control device for an internal combustion engine comprising drive frequency setting means for setting the drive frequency larger when at least one of the engine rotational speed and the vehicle speed is in a low speed range than in a high speed range. A fuel pump drive for an internal combustion engine in which fuel is supplied to a fuel injection valve by an electric fuel pump driven by a PWM signal whose drive frequency is variable, and the fuel pressure is variably controlled by adjusting the drive amount of the fuel pump A control device,
First driving frequency setting means for setting the driving frequency to be larger as the driving amount of the fuel pump is smaller;
A second drive frequency setting means for setting the drive frequency larger when at least one of the engine rotational speed and the vehicle speed is in a low speed range than in a high speed range;
Drive frequency selection for selecting the larger one of the first drive frequency set by the first drive frequency setting means and the second drive frequency set by the second drive frequency setting means and setting it as the drive frequency Means,
A fuel pump drive control device for an internal combustion engine, comprising: A fuel pump drive for an internal combustion engine in which fuel is supplied to a fuel injection valve by an electric fuel pump driven by a PWM signal whose drive frequency is variable, and the fuel pressure is variably controlled by adjusting the drive amount of the fuel pump A control device,
First driving frequency setting means for setting the driving frequency to be larger as the driving amount of the fuel pump is smaller;
When the engine load is in a low load region where the engine load is lower than a predetermined value and the low temperature condition where the engine temperature is lower than the predetermined temperature is satisfied, the fuel pressure is increased from when the engine temperature is not satisfied, and the drive frequency is set by the drive frequency setting means. Third driving frequency setting means for changing and setting the third driving frequency higher than the first driving frequency.
A fuel pump drive control device for an internal combustion engine, comprising:   The first drive frequency setting means has a value that correlates with the drive amount of the fuel pump, such that any one of the duty ratio of the PWM signal, the fuel flow rate from the fuel injection valve, and the intake air flow rate of the engine decreases. The fuel pump drive control device for an internal combustion engine according to claim 2 or 3, wherein the first drive frequency is set to a large value. Fuel pump drive control for an internal combustion engine in which fuel is supplied to a fuel injection valve by an electric fuel pump driven by a PWM signal whose drive frequency is variable and the fuel pressure is variably controlled by adjusting the drive amount of the fuel pump A device,
Basic drive frequency setting means for setting a basic drive frequency of the fuel pump based on an engine operating state;
Upper limit drive frequency setting means for setting an upper limit drive frequency based on the amount of heat generated by driving the fuel pump;
Drive frequency selection means for selecting a smaller one of the basic drive frequency and the upper limit drive frequency and setting it as a drive frequency;
A fuel pump drive control device for an internal combustion engine, comprising:

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