JP2019152171A - Control device - Google Patents

Abstract

To accurately detect an abnormality of a motor of a fuel pump while suppressing a cost.SOLUTION: A control device (100) is for use in a motor (51) for driving a fuel pump (50). The control device comprises: rotation number control means (11) for controlling a rotation number of the motor; temperature detection means (22) for detecting a temperature of fuel passing in the fuel pump; time detection means (12) for detecting a deceleration time up until the rotation number of the motor reaches a second rotation number from a first rotation number when the motor is naturally decelerated after the rotation number of the motor is set to the first rotation number by the rotation number control means; and determination means (13) for determining that an abnormality occurs in the motor when the detected deceleration time reaches a threshold or shorter. The determination means sets the threshold small when the temperature of the fuel is relatively low compared with the case that the temperature of the fuel is relatively high.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device, and more particularly to the technical field of a control device for a motor that drives a fuel pump.

  Deterioration of impellers and bearings constituting the fuel pump cannot be avoided. Deterioration of the impeller or the like leads to a fuel pump failure. This type of device can detect an abnormality of the fuel pump. For example, in the technique described in Patent Document 1, when the motor current value when the pump is operating at a constant rotational speed exceeds a preset lower limit value, it is diagnosed that the pump is out of order.

  In addition, it is determined whether or not the actual deceleration time from the predetermined speed at the time of natural deceleration of the centrifuge rotor driven by the motor to stop is within the range from the minimum deceleration time to the maximum deceleration time. Thus, a technique for detecting a motor abnormality has been proposed (see Patent Document 2). In addition, an abnormality detection method for a pressure regulator provided in the fuel pump (see Patent Document 3) and a method for determining whether the fuel pump drive motor is locked or short-circuited (see Patent Document 4) have been proposed.

Japanese Patent Laid-Open No. 08-075617 JP 2007-045586 A International Publication No. 2012/123985 JP 2012-026359 A

  A small brushless motor is often used as a drive motor for the fuel pump. The change in current associated with a small brushless motor is relatively small. For this reason, in order to detect a motor current value and to detect an abnormality of the fuel pump as in the technique described in Patent Document 1, a highly accurate ammeter is required. A high-accuracy ammeter is expensive and therefore has a technical problem of incurring high costs. Since the technique described in Patent Document 2 is premised on a centrifuge, it is difficult to apply it to detection of abnormality of the fuel pump as it is.

  The present invention has been made in view of the above-described problems, and provides a control device that can accurately detect abnormality of a motor due to deterioration of an impeller, a bearing, and the like of a fuel pump while suppressing cost. This is the issue.

  A control device according to one aspect of the present invention is a control device for a motor that drives a fuel pump, and detects the temperature of the fuel that passes through the fuel pump, and a rotational speed control means that controls the rotational speed of the motor. When the motor is naturally decelerated after the rotation speed of the motor is set to the first rotation speed by the rotation speed control means and the rotation speed control means, the rotation speed of the motor is calculated from the first rotation speed, Time detection means for detecting a deceleration time until the second rotation speed is smaller than the first rotation speed, and determination that the motor is abnormal when the detected deceleration time is equal to or less than a threshold value Means for reducing the threshold when the temperature of the fuel is relatively low compared to when the temperature of the fuel is relatively high.

It is a block diagram which shows the structure of the control apparatus which concerns on embodiment. It is a flowchart which shows the diagnostic process which concerns on embodiment. It is a flowchart which shows the failure sign diagnostic process which concerns on embodiment. It is a flowchart which shows the failure sign possibility determination processing which concerns on embodiment. It is a flowchart which shows the inertial rotation time measurement process which concerns on embodiment.

  An embodiment according to a control device will be described with reference to the drawings.

(Constitution)
The configuration of the control device according to the embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration of a control device according to the embodiment.

  In FIG. 1, the control device 100 is mounted on a vehicle 1. The vehicle 1 includes an engine (not shown), a fuel pump 50 for supplying fuel to the engine, and a motor for driving a brushless motor 51 of the fuel pump 50 (hereinafter referred to as “motor 51” as appropriate). And a driving device 60. The fuel pump 50 includes a pressure regulator 52 in addition to the motor 51.

  The control device 100 includes an ECU (Electronic Control Unit) 10, a rotation speed sensor 21, a fuel temperature sensor 22, a fuel pressure sensor 23, and a notification means 70. In the present embodiment, a part of the functions of the ECU 10 for various electronic controls of the vehicle 1 is used as a part of the control device 100.

  The ECU 10 includes a control unit 11, a deceleration time detection unit 12, and a determination unit 13 as processing blocks that are logically realized therein or as processing circuits that are physically realized. The control unit 11 controls the motor 51 via the motor driving device 60. As a result, the impeller (not shown) of the fuel pump 50 is rotated by the motor 51. The deceleration time detection unit 12 and the determination unit 13 will be described later.

(Diagnosis processing)
The diagnostic processing of the fuel pump 50 performed in the control device 100 configured as described above will be described with reference to the flowcharts of FIGS. In the diagnosis process, an abnormality of the motor 51 due to deterioration of the impeller, the bearing, or the like is detected, and it is diagnosed whether or not the fuel pump 50 has a sign of failure.

  The ECU 10 performs failure sign diagnosis processing (step S1) (see FIG. 2). In the failure sign diagnosis process, first, a failure sign possibility determination process is performed (step S11) (see FIG. 3). In the failure predictability determination process, the determination unit 13 of the ECU 10 determines whether or not the engine is stopped based on, for example, the engine speed detected by a sensor such as an engine rotation sensor (step S111) (FIG. 4). reference).

  In the process of step S111, when it is determined that the engine is not stopped (step S111: No), after the sign prohibition flag is set (step S112), the process is returned. On the other hand, if it is determined in step S111 that the engine is stopped (step S111: Yes), the control unit 11 of the ECU 10 controls the motor driving device 60 so as to drive the motor 51 (step S113). ). At this time, since the engine is stopped, the control unit 11 can control the motor 51 via the motor driving device 60 without considering fuel supply to the engine.

  Next, the determination unit 13 determines whether or not the fuel pressure is stable based on the fuel pressure detected by the fuel pressure sensor 23 (step S114). In the process of step S114, when it is determined that the fuel pressure is stable (step S114: Yes), after the sign permission flag is set (step S115), the process is returned. On the other hand, when it is determined in step S114 that the fuel pressure is not stable (step S114: No), after the sign prohibition flag is set (step S112), the process returns.

  Returning to FIG. 3, after the failure sign possibility determination process (step S <b> 11), the determination unit 13 determines whether or not the sign is permitted (step S <b> 12). In the process of step S12, when it is determined that the sign is not permitted (that is, the sign prohibition flag is set) (step S12: No), the process returns. On the other hand, if it is determined in step S12 that a sign is permitted (that is, a sign permission flag is set) (step S12: Yes), inertial rotation time measurement processing is performed (step S13). .

  In the inertial rotation time measurement process, the control unit 11 controls the rotation speed of the motor 51 via the motor driving device 60 (step S131) (see FIG. 5). Next, the determination unit 13 determines whether or not the rotation speed of the motor 51 is the diagnosis start rotation speed based on the rotation speed of the motor 51 detected by the rotation speed sensor 21 (step S132). In the process of step S132, when it is determined that the rotation speed of the motor 51 is not the diagnosis start rotation speed (step S132: No), the process of step S131 is performed. That is, the process of step S131 is continued until the rotation speed of the motor 51 reaches the diagnosis start rotation speed.

  In the process of step S132, when it is determined that the rotation speed of the motor 51 is the diagnosis start rotation speed (step S132: Yes), the control unit 11 controls the motor drive device 60 to stop driving the motor 51. (Step S133). As a result, power is not supplied from the motor driving device 60 to the motor 51, but the motor 51 continues to rotate due to inertia. In parallel with the process of step S133, the deceleration time detector 12 of the ECU 10 starts time measurement (step S134).

  Next, the determination unit 13 determines whether or not the rotation number of the motor 51 is the diagnosis end rotation number based on the rotation number of the motor 51 detected by the rotation number sensor 21 (step S135). The diagnosis end rotation speed is smaller than the diagnosis start rotation speed. In the process of step S135, when it is determined that the rotation speed of the motor 51 is not the diagnosis end rotation speed (step S135: No), the process of step S135 is performed. On the other hand, in the process of step S135, when it is determined that the rotation speed of the motor 51 is the diagnosis end rotation speed (step S135: Yes), the deceleration time detection unit 12 ends the time measurement (step S136). It is then returned.

  As a result of the series of inertia rotation time measurement processing, the time until the rotation speed of the motor 51 reaches the diagnosis end rotation speed from the diagnosis start rotation speed due to inertia (in other words, due to natural deceleration) (hereinafter referred to as “inertia rotation” as appropriate). Time)) is measured.

  Returning to FIG. 3, after the inertia rotation time measurement process (step S <b> 13), the determination unit 13 sets a specified time based on the output of the fuel temperature sensor 22 (step S <b> 14). The “specified time” is a value that determines whether or not there is a sign of failure in the fuel pump 50, as will be described later. In the present embodiment, the “specified time” is set as a variable value according to the temperature detected by the fuel temperature sensor 22 (that is, the temperature of the fuel passing through the fuel pump 50). Specifically, the “specified time” is set to be shorter when the fuel temperature is relatively low than when the fuel temperature is relatively high.

  The viscosity of the fuel increases as the temperature of the fuel decreases. That is, the load applied to the motor 51 increases as the fuel temperature decreases. For this reason, the inertial rotation time is shorter when the temperature of the fuel is relatively low than when the temperature of the fuel is relatively high. In order to consider the influence of the viscosity of the fuel on the inertial rotation time, the “specified time” is set as a variable value according to the temperature of the fuel as described above.

  Next, the determination unit 13 determines whether or not the inertial rotation time is equal to or shorter than a specified time (step S15). In the process of step S15, when it is determined that the inertial rotation time is longer than the specified time (step S15: Yes), after the no sign flag is set (step S16), the process is returned. On the other hand, in the process of step S15, when it is determined that the inertial rotation time is equal to or shorter than the specified time (step S15: No), after a flag with a sign is set (step S17), the process returns.

  When the impeller, bearing, etc. of the fuel pump 50 deteriorate, the rotational resistance of the motor 51 increases (that is, the load on the motor 51 increases). The “specified time” is set without considering the deterioration of the impeller or the like (in other words, assuming that there is no deterioration of the impeller or the like). Therefore, the inertial rotation time when the impeller or the like is deteriorated is the specified time. Shorter than. For this reason, when it is determined that the inertial rotation time is equal to or less than the specified time, a flag with a sign is set (in other words, it is determined that the motor 51 is abnormal).

  Returning to FIG. 2, after the failure sign diagnosis process (step S1), the determination unit 13 determines whether or not there is a sign (step S2). When it is determined in step S2 that there is no sign (step S2: No), the process ends. Thereafter, after a predetermined time (for example, several tens of milliseconds to several hundreds of milliseconds) has elapsed, the process of step S1 is performed again. When it is determined that there is no sign in the process of step S2, the sign is not permitted in the process of step S12 described above (see FIG. 3), not only when the no sign flag is set (see FIG. 3). That is, it is determined that the sign prohibition flag is set).

  In the process of step S2, when it is determined that there is a sign (that is, the sign flag is set) (step S2: Yes), a failure probability calculation process is performed (step S3). In the failure probability calculation process, a value obtained by dividing the number of times that the sign flag has been set in the past N failure sign diagnosis processes by N is calculated as the failure probability. That is, “failure probability = (the number of times that a flag with a sign has been raised in the past N sign-of-failure diagnosis processes) / N”.

  Next, the determination unit 13 determines whether or not the failure probability is equal to or higher than a specified probability (step S4). In the process of step S4, when it is determined that the failure probability is less than the specified probability (step S4: No), the process is terminated. Thereafter, after a predetermined time has elapsed, the process of step S1 is performed again.

  On the other hand, if it is determined in step S4 that the failure probability is equal to or higher than the specified probability (step S4: Yes), failure predictor notification processing is performed (step S5). In the failure sign notification process, the control unit 11 controls the notification means 70 so as to display that the fuel pump 50 has a sign of failure and / or to issue an alarm.

(Technical effect)
When detecting a motor current value and detecting a motor abnormality caused by deterioration of an impeller, a bearing or the like, for example, there are the following problems. That is, a relatively small brushless motor is often used for the motor of the fuel pump. Even if the motor load increases due to deterioration of the impeller or the like, the motor current value increases only slightly. For this reason, an ammeter with relatively high accuracy is required, resulting in high costs. In addition to the deterioration of the impeller and the like, the motor current value also fluctuates due to, for example, fluctuations in the power supply voltage and motor load, so there is a possibility that a motor abnormality may be detected by mistake. In addition, since failure diagnosis (that is, detection of motor abnormality) is performed while the motor is energized, processing related to motor control and processing related to failure diagnosis are performed in parallel, increasing the processing load. For this reason, for example, a relatively high-performance microcomputer or a dedicated IC (Integrated Circuit) is required, resulting in high costs.

  In the control device 100, it is determined whether or not there is an abnormality in the motor 51 by measuring the inertial rotation time after the drive of the motor 51 is stopped and comparing the inertial rotation time with a specified time. For this reason, according to the said control apparatus 100, cost can be suppressed compared with the comparative example which detects a motor electric current value and detects abnormality of the motor 51. FIG. In addition, because the inertial rotation time is performed when the fuel pressure is stable (see steps S114 and S115 in FIG. 4, steps S12 and S13 in FIG. 3, and FIG. 5), according to the control device 100, False detection can be suppressed. Furthermore, since most of the above-described diagnosis processing is performed when the motor 51 is stopped, an increase in processing load can be suppressed.

  In the control device 100, in particular, the “specified time” for determining whether or not the motor 51 is abnormal is set as a variable value corresponding to the temperature of the fuel. For this reason, according to the control device 100, even if the load of the motor 51 fluctuates because the temperature of the fuel changes (that is, the viscosity of the fuel changes), it is determined whether or not the motor 51 is abnormal. Can be judged well. As a result, the accuracy of the diagnostic process described above can be improved.

  The inertial rotation time is measured while the engine of the vehicle 1 is stopped (see, for example, step S111 in FIG. 4). Since the engine is stopped, there is no fuel consumption and the fuel pressure stabilizes. As a result, the inertial rotation time can be measured in a state where the motor load is stable, so that the accuracy of the above-described diagnosis process can be improved. Further, in the failure probability calculation process (see step S3 in FIG. 2), the failure probability is calculated based on the result of the failure sign diagnosis process a plurality of times (N times). For this reason, it is possible to prevent erroneous detection caused by, for example, a measurement error.

<Modification>
The diagnosis start rotational speed (see, for example, step S132 in FIG. 5) may be equal to or higher than the rotational speed at which the fuel pressure at which the valve of the pressure regulator 52 is released is reached. If comprised in this way, a fuel pressure can be made constant and the measurement of inertial rotation time can be started, Therefore The precision of a diagnostic process can be improved. Furthermore, since the diagnosis starting rotational speed is relatively high and the inertial rotational time is also relatively long, the accuracy of the diagnostic processing can be improved.

  Various aspects of the invention derived from the embodiments and modifications described above will be described below.

  A control device according to an aspect of the invention is a control device for a motor that drives a fuel pump, and detects the temperature of the fuel that passes through the fuel pump, and a rotational speed control means that controls the rotational speed of the motor. When the motor is naturally decelerated after the rotational speed of the motor is set to the first rotational speed by the temperature detection means and the rotational speed control means, the rotational speed of the motor is calculated from the first rotational speed, Time detection means for detecting a deceleration time until the second rotation speed is smaller than the first rotation speed, and determination means for determining that the motor is abnormal when the detected deceleration time is equal to or less than a threshold value The determination means reduces the threshold when the temperature of the fuel is relatively low compared to when the temperature of the fuel is relatively high.

  In the above-described embodiment, the control unit 11 corresponds to an example of a rotation speed control unit, the fuel temperature sensor 22 corresponds to an example of a temperature detection unit, the deceleration time detection unit 12 corresponds to an example of a time detection unit, The determination unit 13 corresponds to an example of a determination unit. The “diagnosis start rotation speed”, “diagnosis end rotation speed”, “inertia rotation time”, and “specified time” in the above-described embodiment are “first rotation speed”, “second rotation speed”, and “deceleration time”, respectively. ”And“ threshold ”.

  In the control device, it is determined that there is an abnormality in the motor when the deceleration time until the motor rotational speed naturally decelerates from the first rotational speed to the second rotational speed is equal to or less than a threshold value. In particular, in the control device, in consideration of the state of the fuel (for example, viscosity), the threshold value is made smaller when the fuel temperature is relatively low than when the fuel temperature is relatively high.

  Compared with the comparative example in which the motor current value is detected and the motor abnormality is determined, the control device does not require a relatively high accuracy ammeter. For example, the motor current value caused by fluctuations in the power supply voltage or the like It is not necessary to take into account fluctuations. In the control device, since the threshold is set in consideration of the fuel state, it is possible to suppress the influence of the fluctuation of the motor load caused by the fuel state on the determination result. Therefore, according to the control device, it is possible to accurately detect abnormality of the motor due to deterioration of the impeller, the bearing and the like of the fuel pump while suppressing the cost.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. Moreover, it is included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 10 ... ECU, 11 ... Control part, 12 ... Deceleration time detection part, 13 ... Determination part, 21 ... Speed sensor, 22 ... Fuel temperature sensor, 23 ... Fuel pressure sensor, 50 ... Fuel pump, 51 ... Brushless Motor, 52 ... Pressure regulator, 60 ... Motor drive device, 70 ... Notification means, 100 ... Control device

Claims (1)

A control device for a motor that drives a fuel pump,
A rotational speed control means for controlling the rotational speed of the motor;
Temperature detecting means for detecting the temperature of the fuel passing through the fuel pump;
When the motor is naturally decelerated after the rotation speed control means sets the rotation speed of the motor to the first rotation speed, the rotation speed of the motor is less than the first rotation speed from the first rotation speed. A time detecting means for detecting a deceleration time until the second rotational speed becomes smaller,
A determination means for determining that the motor has an abnormality when the detected deceleration time is equal to or less than a threshold;
With
The control unit is configured to reduce the threshold when the temperature of the fuel is relatively low as compared with a case where the temperature of the fuel is relatively high.

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