JP2008115718A - Motor-driven pump and control method for motor-driven pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor-driven pump reduced in size, suppressing operating sounds, and to provide a control method for a motor-driven pump. <P>SOLUTION: The motor is rotated at a revolution speed higher than one securing a required pump delivery amount, when 100% of source voltage is applied thereto. A microcomputer makes a PWM control of the motor revolution speed to be a target revolution speed N1 securing a required pump delivery amount. During operation of the motor-driven pump, the motor revolution speed is controlled to be the target revolution speed N1 to reduce the operating sounds of the motor and the pump. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric pump that drives a pump with a motor and a method for controlling the electric pump.

  Conventionally, for example, a configuration shown in Patent Document 1 is known as an electric pump used as an auxiliary machine such as a fuel pump, a water pump, an oil pump, and a transmission pump of a vehicle. As shown in FIG. 3, the electric pump 51 of the same document is configured integrally with a pump 52 that circulates liquid such as water and oil, and a motor 53 that drives the pump 52. The electric pump 51 is configured such that the output shaft of the motor 53 and the drive shaft of the pump 52 are combined by a single shaft 54 from the viewpoint of reducing the number of parts and reducing the size.

As shown in the figure, the motor 53 of the electric pump 51 is energized and controlled by a microcomputer 55 through a motor drive circuit 56. Thereby, the electric power from the battery 57 mounted on the vehicle is suitably supplied to the motor 53, and the motor 53 rotates at a rotation speed at which a predetermined pump discharge amount is obtained. The relationship between the motor rotational speed and the motor torque when the power supply voltage is applied 100%, for example, the motor torque is plotted on the horizontal axis and the motor rotational speed is plotted on the vertical axis as shown by the characteristic line L in FIG. When in inverse proportion. That is, the motor rotation speed decreases as the motor torque increases. For example, if the required pump discharge amount can be secured when the motor torque T = T1 and the motor rotation speed N = N1, the motor 53 is driven and controlled so that the motor rotation speed N = N1. . That is, conventionally, the motor 53 of the electric pump 51 has a characteristic in which the intersection point P between the motor torque T = T1 and the motor rotation speed N = N1 is located on the characteristic line L shown in FIG. .
JP-A-2005-337025

  Generally, the discharge rate per unit time increases as the rotational speed of the electric pump 51 increases. However, the operating sound of the electric pump 51 increases as it rotates at a higher speed. In vehicles, high silence is required. For this reason, in order to ensure the said quietness, the pump 52 of the electric pump 51 was employed with a discharge amount as much as possible per one rotation. In this way, even when the number of rotations of the pump 52 is reduced, the discharge amount per unit time can be secured. In this case, the motor 53 of the electric pump 51 is not a high rotation / small torque type, but a low rotation / high torque type.

  However, it is generally difficult to reduce the size of a low-rotation / high-torque motor. This is because it is necessary to increase the outer diameter of the rotor magnet or increase the number of turns of the exciting coil of the stator when a low-rotation / high-torque motor is configured. For this reason, although the operation noise of the electric pump 51 can be suppressed by adopting a low-rotation / high-torque motor as a drive source of the electric pump 51, there is a limit to downsizing the motor 53 and thus the electric pump 51 as a whole. there were. In the vehicle, in addition to the above-described quietness, further miniaturization of auxiliary machinery such as an electric pump mounted on the vehicle is required from the viewpoint of securing a living space.

  In order to satisfy such a demand for miniaturization, it is conceivable to employ a motor with a small physique. However, as the motor becomes smaller, the motor shifts to a high-rotation / low-torque motor with a smaller number of exciting coils. For this reason, when a motor with a small physique is adopted, the electric pump 51 can be reduced in size, but as described above, the electric pump 51 rotates at a high speed, and there is a concern about the problem of operating noise. Therefore, it has been difficult to adopt a motor with high rotation and low torque. As described above, there is a limit to miniaturization of the electric pump 51 in which the low-rotation / high-torque pump 52 with less operation noise is employed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric pump and a method for controlling the electric pump that can be downsized while suppressing operation noise.

  According to the first aspect of the present invention, the rotational speed of the motor is obtained based on the rotational position of the motor detected by the rotational angle detecting means, and the motor is driven and controlled through the motor drive circuit based on the rotational speed, thereby In the electric pump comprising a control means for controlling the discharge amount, the motor rotates at a rotation speed higher than the rotation speed at which the required pump discharge amount is secured when the power supply voltage is applied 100%. The gist of the invention is that the control means outputs a motor control signal to the motor drive circuit for setting the rotational speed of the motor to a target rotational speed at which a required pump discharge amount is secured. And

  In general, a motor that rotates at a higher rotational speed can be reduced in size. According to the present invention, miniaturization can be achieved by employing such a high rotation / low torque type small motor as a pump drive source. In general, the motor and the pump become louder as they rotate at higher speed. On the other hand, according to the present invention, when the electric pump is operated, the motor rotates at a target rotational speed at which a required pump discharge amount is secured. This target rotational speed is lower than the motor rotational speed when 100% of the power supply voltage is applied. For this reason, compared with the case where it uses in the state which applied 100% of power supply voltage to the high rotation and high torque type motor, the reduction of the operation sound of a motor and by extension, an electric pump is achieved. Further, even when a high-rotation / high-torque motor is employed, it is possible to cope with a low-rotation / high-torque pump.

  According to a second aspect of the present invention, in the electric pump according to the first aspect, the motor driving circuit is a PWM inverter circuit that converts a DC voltage from a DC power source into an AC voltage and supplies the AC voltage to the motor. Is the gist.

  When it is going to secure a predetermined motor torque, a motor with a high rotation and low torque type and a small physique requires more current. In recent years, there is still a tendency for vehicles to be electronic, and accordingly, further reduction in power consumption of the electric pump is required. In such a situation, according to the present invention, the motor is PWM-controlled so that the rotational speed of the motor is the target rotational speed at which the required pump discharge amount is secured. That is, the control means sets the duty ratio of the PWM signal so that the rotation speed of the motor becomes the target rotation speed. As a result, the effective voltage applied to the motor, and hence the amount of current supplied to the motor, is smaller than when 100% of the voltage of the DC power supply is applied. As a result, the motor is suitably driven at the target rotational speed.

  When such PWM control is performed, the current value (DC power supply current value) on the DC power supply side of the motor drive circuit (inverter circuit) is smaller than the current value (motor current value) supplied to the motor. This was confirmed by the inventors' experiment. This indicates that the motor torque is secured even though the DC power supply current value is smaller than the current value required to generate the predetermined motor torque. Therefore, it is possible to suppress the consumption of the DC power supply while securing the motor torque.

  According to a third aspect of the present invention, in the electric pump according to the first or second aspect, when the rotational speed of the motor reaches the target rotational speed, the operating sound level of the pump is mounted on the electric pump. The gist is that a value that is not more than the threshold required for the subject is adopted.

According to the present invention, since the operating sound level is equal to or lower than the threshold required for the mounting target of the electric pump, the operating sound during operation of the electric pump is suitably suppressed.
According to a fourth aspect of the present invention, there is provided the electric pump according to any one of the first to third aspects, wherein the storage means stores a target rotational speed at which a required pump discharge amount is secured. The gist of the invention is that the control means outputs a motor control signal to the motor drive circuit so that the rotation speed of the motor becomes the target rotation speed stored in the storage means.

According to the present invention, the motor is suitably controlled so as to reach the target rotational speed stored in the storage means.
According to a fifth aspect of the present invention, the rotational speed of the motor is obtained based on the rotational position of the motor detected by the rotational angle detection means, and the pump is driven by a motor that is driven and controlled through a motor drive circuit based on the rotational speed. In the electric pump control method as described above, the motor employs a motor that rotates at a higher rotational speed than the rotational speed at which a required pump discharge amount is ensured when the power supply voltage is applied 100%. The gist of the invention is to perform PMW control of the motor so that the rotational speed of the motor is the rotational speed at which a required pump discharge amount is secured.

  According to the present invention, as in the first aspect of the present invention, the motor can be reduced in size by adopting a small motor of high rotation and low torque type as a pump drive source. By rotating the motor at a target rotational speed at which a required pump discharge amount is ensured, the operating noise of the motor, and hence the pump, can be reduced. Further, similarly to the second aspect of the invention, the motor is PWM controlled so that the rotational speed of the motor is set to a target rotational speed at which a required pump discharge amount is secured. As described above, when PWM control is performed, the current value on the DC voltage side (DC power supply current value) is smaller than the current value supplied to the motor (motor current value). Therefore, the consumption of the DC power supply is suppressed while securing the motor torque.

  According to the present invention, it is possible to reduce the size while suppressing the operation sound of the electric pump.

  Next, an embodiment in which the present invention is embodied in an electric pump used as an auxiliary machine such as a water pump, an oil pump, and a transmission pump of a vehicle will be described.

  As shown in FIG. 1, the electric pump 11 includes a motor 12 as a driving source, a gear pump 13 that is driven by the driving force of the motor 12, and a control board 14 that drives and controls the motor 12. The control board 14 is provided with a microcomputer 15 and a motor drive circuit 16 as control means. The microcomputer 15 includes a storage unit 15 a such as an EEPROM as storage means, and is connected to the motor 12 via a motor drive circuit 16. The microcomputer 15 and the motor drive circuit 16 are connected to a battery 17 as a DC power source mounted on the vehicle.

  The motor 12 is a brushless motor, and rotates at a rotational speed higher than the rotational speed at which a required pump discharge amount is secured when 100% of the DC power supply voltage is applied (when the duty ratio is 100%). The thing is adopted. The motor 12 includes a rotation angle sensor 12a such as a hall sensor (Hall IC) as a rotation angle detection means. The rotation angle sensor 12a detects the rotation angle of the motor 12, more precisely, rotation position information (magnetic pole position information) of a rotor (not shown) constituting the motor 12, and sends the information (motor rotation angle signal θm) to the microcomputer 15. send.

  As the gear pump 13, a gear pump having a low rotation and a high torque, that is, a pump having a discharge amount per rotation as much as possible is adopted. Further, the gear pump 13 employs a gear pump whose operating sound level is equal to or lower than a threshold required for the vehicle on which the electric pump 11 is mounted when the rotational speed of the motor 12 reaches the target rotational speed.

  The storage unit 15a stores a control program such as a motor control program (pump control program) executed by the microcomputer 15, various data, and the like. As the data, for example, there is a target rotational speed at which a required pump discharge amount is secured. The target rotational speed is a value for obtaining a required pump discharge amount when the motor 12 rotates at the rotational speed, and is obtained in advance by an experiment using an apparatus model.

  The microcomputer 15 executes the motor control program stored in the storage unit 15a based on the motor rotation speed information from the rotation speed sensor (not shown). That is, the microcomputer 15 drives the motor 12 by outputting to the motor drive circuit 16 a motor control signal for setting the number of rotations of the motor 12 to a target number of rotations that ensures a required pump discharge amount. Control.

  Here, the motor drive circuit 16 is a PWM inverter circuit that converts a DC voltage from the battery 17 into an AC voltage and supplies the AC voltage to the motor 12. Specifically, as shown in FIG. 1, the motor drive circuit 16 includes a series circuit of FETs (field effect transistors) 21U and 22U, a series circuit of FETs 21V and 22V, and a series circuit of FETs 21W and 22W in parallel. It is configured by being connected. A connection point PU between the FETs 21U and 22U is connected to a U-phase winding (not shown) of the motor 12, a connection point PV between the FETs 21V and 22V is connected to a V-phase winding (not shown) of the motor 12, and a connection between the FETs 21W and 22W. Point PW is connected to a W-phase winding (not shown) of motor 12.

  The microcomputer 15 performs PWM calculation based on the difference between the motor rotation speed information (actual rotation speed of the motor 12) from the rotation angle sensor 12a and the target rotation speed stored in the storage unit 15a, and the calculation result The motor control signal is output to the motor drive circuit 16 based on the above, more precisely to the FETs 21U and 22U, FETs 21V and 22V, and FETs 21W and 22W. The motor control signal output from the microcomputer 15 defines the duty ratio (ON duty) of the FETs 21U and 22U, FETs 21V and 22V, and FETs 21W and 22W.

  The motor drive circuit 16 supplies a motor current (three-phase excitation current) to the motor 12 based on the motor control signal sent from the microcomputer 15, and the motor 12 is driven based on the motor current. That is, when the motor control signal is applied to gate terminals (not shown) of the FETs 21U, 22U, 21V, 22V, 21W, and 22W at a predetermined timing, the FETs are turned on and off. Thereby, the DC voltage of the battery 17 is converted into a three-phase (U-phase, V-phase, W-phase) AC voltage and supplied to the motor 12. Specifically, the motor 12 is driven in accordance with a pulse signal subjected to pulse width modulation, that is, a PWM signal (voltage value). Then, the amount of current supplied to the motor 12 is adjusted by the duty ratio of the PWM signal, and the rotational speed (rotational speed) of the motor 12 is controlled.

  The microcomputer 15 sets the duty ratio of the PWM signal to be large when increasing the rotational speed of the motor 12. Then, the current supplied to the motor 12 increases, and the rotational speed (rotational speed) of the motor 12 increases accordingly. Conversely, the microcomputer 15 sets the duty ratio of the PWM signal to be small when the rotational speed of the motor 12 is decreased. Then, the current supplied to the motor 12 decreases, and the rotational speed (rotational speed) of the motor 12 decreases accordingly.

<Operation of electric pump>
Next, the operation of the electric pump configured as described above will be described.
When the electric pump 11 is operated, the microcomputer 15 outputs a motor control signal to the motor drive circuit 16. The motor drive circuit 16 outputs a PWM signal to the motor 12 based on the motor control signal, and the motor 12 is driven according to the PWM signal. Moreover, the microcomputer 15 calculates | requires the rotation speed of the motor 12 based on the rotation position information of the motor 12 detected by the rotation angle sensor 12a. Then, the microcomputer 15 passes through the motor drive circuit 16 so that the rotational speed of the motor 12 becomes the target rotational speed based on the difference between the obtained actual rotational speed and the target rotational speed stored in the storage unit 15a. Drive control of the motor 12 is performed.

  Here, the motor 12 employed in the present embodiment has characteristics as shown in FIG. That is, the relationship between the motor rotation speed N and the motor torque T is a characteristic line when 100% of the above-described characteristic line L during PWM control indicated by a solid line and the voltage of the battery 17 indicated by a broken line are applied 100%. As indicated by Lmax, when the motor torque T is on the horizontal axis and the motor rotation speed N is on the vertical axis, the relationship is inversely proportional. That is, the motor rotation speed N decreases as the motor torque T increases. In the present embodiment, the gear pump 13 is employed in which the required pump discharge amount is secured when the motor rotation speed N = N1 and the motor torque T = T1. Further, the intersection P between the motor torque T = T1 and the motor rotation speed N = N1 is located on the characteristic line L indicated by the solid line in FIG. The microcomputer 15 performs PWM control on the motor 12 so that the motor rotation speed N of the motor 12 is N = N1.

  As described above, the PWM control of the motor 12 causes the gear pump 13 to rotate (integrally) in synchronism with the motor 12, so that liquid such as fuel, water, and oil passes through a suction port and a discharge port (not shown). Perform inhalation and discharge. In the discharge process of the gear pump 13, a required pump discharge amount is secured.

Hereinafter, the PWM control of the motor 12 will be described in detail.
In the present embodiment, the motor 12 employs a motor that rotates at a rotational speed higher than the rotational speed at which a required pump discharge amount is ensured when a power supply voltage is applied 100%. For this reason, the microcomputer 15 applies the voltage of the battery 17 to the duty ratio of the PWM signal so that the rotational speed of the motor 12 is the target rotational speed N1 at which the required pump discharge amount is secured. Set to a smaller value than.

  As a result, as shown by the solid line in FIG. 2, the characteristic line L indicating the relationship between the motor rotational speed and the motor torque is obtained when the duty ratio of the PWM signal indicated by the broken line in FIG. The characteristic line Lmax is parallel to the side where the value of the motor rotation speed N becomes smaller than the characteristic line Lmax (when the voltage of 17 is applied 100%). The amount of current supplied to the motor 12 is smaller than when 100% of the voltage of the battery 17 is applied, and the motor 12 rotates at a target rotational speed N1 that ensures a required pump discharge amount. . At this time, the motor torque T = T1. Incidentally, when 100% of the voltage of the battery 17 is applied to the motor 12, the duty ratio of the PWM signal is set to 100%.

  Therefore, by performing the motor control as described above, the high rotation / high torque type motor 12 can be made to correspond to the low rotation / high torque type gear pump 13. When the electric pump 11 is operated, the high-rotation / low-torque motor 12 is not driven at the maximum rotation speed, and is driven by being limited to the target rotation speed N1 smaller than the maximum rotation speed. The operating noise of the motor 12 and the gear pump 13 is suppressed. This is because the operating noise of the motor 12 and the gear pump 13 increases as the rotational speed is increased. Further, the gear pump 13 employs a gear pump 13 whose operating sound level is equal to or lower than a threshold required for the vehicle on which the electric pump 11 is mounted when the rotational speed of the motor 12 reaches the target rotational speed N1. Therefore, the quietness of the vehicle is enhanced.

  Further, when the PWM control as described above is performed, the characteristic line M indicating the relationship between the motor torque T and the current value Idc on the battery 17 side of the motor drive circuit 16 is represented by a solid line in FIG. The slope is smaller than the characteristic line Mmax when the duty ratio of the PWM signal indicated by the broken line in the figure is set to 100% (when the voltage of the battery 17 is applied 100%). From this, for example, when a predetermined motor torque T (for example, T = T1) is to be obtained, the voltage of the battery 17 is reduced as in the present embodiment, rather than when 100% of the voltage of the battery 17 is applied. The current value Idc on the battery 17 side of the motor drive circuit 16 is smaller when 100% is not applied. Therefore, according to the motor control method of the present embodiment, the power consumption of the motor 12 can be reduced.

  The current value on the battery 17 side of the motor drive circuit 16 (current value at the point Pdc shown in FIG. 1) is the current value supplied to the motor 12 (current values at the points Pu, Pv, and Pw shown in FIG. 1). It was confirmed by an experiment using the device model of the present inventor that the value is smaller than (1). This is because although the current value on the battery 17 side of the motor drive circuit 16 is smaller than the current value required on the motor 12 side to obtain the predetermined motor torque T, the motor torque T is Indicates that it will be secured. Therefore, it is possible to suppress the consumption of the battery 17 while securing the motor torque T.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The motor 12 employs a motor that rotates at a rotational speed higher than the rotational speed at which a required pump discharge amount is secured when 100% of the power supply voltage is applied. The microcomputer 15 controls the motor 12 so that the rotational speed of the motor 12 is set to the target rotational speed N1 at which a necessary pump discharge amount is secured.

  In general, a motor that rotates at a higher rotational speed can be reduced in size. By adopting such a high rotation / low torque type small motor 12 as a drive source of the gear pump 13, the size can be reduced. In general, the motor and the pump become louder as they rotate at higher speed. On the other hand, during operation of the electric pump, the motor 12 rotates at a target rotational speed N1 that ensures a necessary pump discharge amount. This target rotation speed N1 is lower than the motor rotation speed when 100% of the power supply voltage is applied. For this reason, compared with the case where it uses in the state which applied 100% of power supply voltage to the motor 12 of high rotation and high torque type, the reduction of the operation sound of the motor 12 and by extension, the electric pump 11 is achieved. Further, even when a high-rotation / high-torque motor is employed, it is possible to cope with a low-rotation / high-torque pump.

(2) The motor drive circuit 16 is a PWM inverter circuit that converts the DC voltage from the battery 17 into an AC voltage and supplies the AC voltage to the motor 12.
When it is going to secure a predetermined motor torque, a motor with a high rotation and low torque type and a small physique requires more current. In recent years, there is still a tendency for vehicles to be electronic, and accordingly, further reduction in power consumption of the electric pump is required. In such a situation, according to the present embodiment, the motor 12 is PWM-controlled so that the rotation speed of the motor 12 is the target rotation speed N1 at which the required pump discharge amount is ensured. That is, the microcomputer 15 sets the duty ratio of the PWM signal so that the rotational speed of the motor 12 is the target rotational speed N1. As a result, the effective voltage applied to the motor 12, and thus the amount of current supplied to the motor 12, is smaller than when 100% of the voltage of the battery 17 is applied. As a result, the motor 12 is suitably driven at the target rotational speed N1.

  When such PWM control is performed, the current value (DC power supply current value) on the battery 17 side of the motor drive circuit 16 (inverter circuit) is smaller than the current value (motor current value) supplied to the motor 12. It was confirmed by experiments of the present inventors that This indicates that the motor torque is secured even though the DC power supply current value is smaller than the current value required to generate the predetermined motor torque. Therefore, consumption of the battery 17 can be suppressed while securing the motor torque.

  (3) When the rotational speed of the motor 12 reaches the target rotational speed N1, a pump whose operating sound level is equal to or lower than the threshold required for the vehicle on which the electric pump is mounted is adopted. . For this reason, the operation sound at the time of the driving | operation of the electric pump 11 can be suppressed suitably.

  (4) The microcomputer 15 includes a storage unit 15a in which the target rotation speed N1 that secures a necessary pump discharge amount is stored. The microcomputer 15 outputs a motor control signal to the motor drive circuit 16 so as to set the rotation speed of the motor 12 to the target rotation speed N1 stored in the storage unit 15a. In this way, the motor 12 is suitably driven and controlled so as to reach the target rotational speed N1 stored in the storage unit 15a.

In addition, you may implement the said embodiment as follows.
In the present embodiment, a brushless DC motor is employed as the motor 12, but a brushed DC motor can also be employed.

In the present embodiment, the gear pump 13 is employed, but other rotary pumps such as a vane pump or a screw pump can also be employed.
-Although this Embodiment demonstrated the case where the electric pump 11 was mounted in a vehicle, the mounting object of the said electric pump 11 is not restricted to a vehicle. For example, it may be mounted on a machine tool.

The block circuit diagram which shows schematic structure of the electric pump of this Embodiment. The characteristic view which similarly shows the relationship between motor rotation speed and motor torque. The block circuit diagram which shows schematic structure of the conventional electric pump. The characteristic view which similarly shows the relationship between motor rotation speed and motor torque.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Electric pump, 12 ... Motor, 12a ... Rotation angle sensor (rotation angle detection means), 15 ... Microcomputer (control means), 15a ... Memory | storage part (memory | storage means), 16 ... Motor drive circuit (inverter circuit), 17 ... Battery (DC power supply), N ... Rotational speed, N1 ... Target rotational speed.

Claims (5)

Control means for controlling the discharge amount of the pump by obtaining the rotational speed of the motor based on the rotational position of the motor detected by the rotational angle detection means, and driving the motor through a motor drive circuit based on the obtained rotational speed. In an electric pump comprising
The motor employs a motor that rotates at a rotational speed higher than the rotational speed at which a required pump discharge amount is secured when a power supply voltage is applied 100%.
The control means is an electric pump that outputs a motor control signal for setting the rotation speed of the motor to a target rotation speed at which a required pump discharge amount is secured to a motor drive circuit. The electric pump according to claim 1,
The motor drive circuit is an electric pump that is a PWM inverter circuit that converts a DC voltage from a DC power source into an AC voltage and supplies the AC voltage to the motor. In the electric pump according to claim 1 or 2,
An electric pump that employs a pump whose operating sound level is equal to or lower than a threshold required for an electric pump mounting target when the rotational speed of the motor reaches the target rotational speed. Comprising storage means for storing a target rotational speed at which a required pump discharge amount is secured;
The said control means outputs a motor control signal to a motor drive circuit so that the rotation speed of a motor may be made into the target rotation speed memorize | stored in the said memory | storage means. Electric pump. In a method for controlling an electric pump, the number of rotations of the motor is obtained based on the rotation position of the motor detected by the rotation angle detection means, and the pump is driven by a motor that is driven and controlled through a motor drive circuit based on the number of rotations. ,
The motor employs a motor that rotates at a rotational speed higher than the rotational speed at which a required pump discharge amount is secured when a power supply voltage is applied 100%.
A method for controlling an electric pump, wherein the motor is subjected to PMW control so that the rotation speed of the motor is set to a rotation speed at which a required pump discharge amount is secured.

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