JP2000304149A - Stepping motor type flow rate control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high torque during normal operation, to suppress the increase of the temperatures of a switching element and a stator coil by controlling a drive current during a high temperature, and to miniaturize and standardize an ECU. SOLUTION: This control device comprises a stepping motor 1 consisting of a rotor 2 having a rotary shaft 5, a stator 3 having a stator coil 6, and a housing 7 rotatably supporting the rotor 2 and holding the stator 3; a flow rate control valve 12 coupled to and driven by the rotary shaft 5 of the stepping motor 1; a terminal group 19 provided on the housing 7 of the stepping motor 1 and connected to an external terminal 9 and a stator coil 6; and a circuit board 17 on which a switching element to supply a drive current to the stator coil 6 is mounted and which is mounted on the housing 7 and electrically connected to the terminal group 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor type flow control device used for an internal combustion engine for a vehicle.

[0002]

2. Description of the Related Art A stepping motor type valve is often used in a flow control device for controlling an intake system of a vehicle internal combustion engine. FIG. 6 shows a conventional example, for example, Japanese Patent Application Laid-Open No. H3-1726.
It is an example of an idling speed control device for an internal combustion engine for a vehicle disclosed in Japanese Patent Application Publication No. 89-89. In the figure, reference numeral 1 denotes a stepping motor including a rotor 2 and a stator 3;
Is constituted by a multi-pole magnetized permanent magnet 4 and a rotating shaft 5, and the stator 3 is constituted by a stator coil 6 and a magnetic pole (not shown). The stator 3 is held by a housing 7, and the rotor 2 is rotatably supported by bearings 8 provided on the housing 7.

[0003] Reference numeral 9 denotes a connector having a terminal 10,
The controller is provided separately from the stepping motor 1 to supply current to the stator coil 6 from a controller (not shown). The controller (not shown) inputs and calculates the state of the internal combustion engine (hereinafter, referred to as a control unit). And a drive circuit having a switching element that receives a signal from the ECU and supplies current to the stepping motor 1. Reference numeral 12 denotes a valve body for controlling the idling speed by adjusting the intake air amount of the internal combustion engine together with the valve seat 13.
Is held in such a manner that it can move only in the axial direction and cannot rotate.

[0004] In the idling rotational speed control device configured as described above, if it becomes necessary to control the idling rotational speed due to, for example, a load fluctuation of the internal combustion engine, E
The CU outputs a signal pulse according to the control content, and the drive circuit operates the switching element in accordance with the signal to energize the stator coil 6 and rotate the rotor 2 by a predetermined angle. By the rotation of the rotor 2, the valve body 12, which is screwed and held non-rotatably, moves in the axial direction to change the distance between the valve body 12 and the valve seat 13, and the flow rate of the intake air flowing through the inner diameter of the valve seat 13. To control the idling speed.

[0005]

SUMMARY OF THE INVENTION High response and small size are required for a flow control device for an internal combustion engine for a vehicle. In order to obtain high responsiveness with the above-described stepping motor type flow control device, it is necessary to increase the torque of the motor, and to increase the torque of the motor, it is necessary to increase the ampere-turn of the stator coil as much as possible. is necessary. However, there is a limit in increasing the ampere-turn of the stator coil in a flow control device for a vehicle, which may be required to be miniaturized and the ambient temperature may be high. There was a limit to the improvement.

The drive circuit for driving the stepping motor is an electronic circuit, which is usually integrated with the same electronic circuit, the ECU, and is formed separately from the stepping motor. However, the specifications of the switching elements and the like of the drive circuit are determined by the characteristics of the stepping motor, and the specifications of the ECU are determined by the control contents. Since the number of models is increased and a switching element is a heating element, a heat sink for heat dissipation is indispensable, and there is a problem that a control device in which an ECU and a drive circuit are integrated becomes large.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems. A drive circuit is formed separately from an ECU and is integrated with a stepping motor, and a drive current limiting circuit is added. By providing a heat-sensitive element in the coil and controlling the drive current by temperature, a high torque can be obtained in normal times, and at high temperatures, the drive current is controlled to suppress the temperature rise of the switching element and stator coil, and the ECU It is an object of the present invention to obtain a stepping motor type flow control device capable of reducing the size and standardizing the device.

[0008]

SUMMARY OF THE INVENTION A stepping motor type flow controller according to the present invention rotatably supports a rotor having a rotating shaft, a stator having a stator coil, and holds the stator. A stepping motor constituted by a housing, a flow control valve coupled to and driven by a rotating shaft of the stepping motor, a terminal group provided in the housing of the stepping motor and connected to an external terminal and a stator coil; And a circuit board on which a switching element for supplying a drive current to the stator coil is mounted and which is electrically connected to the terminal group.

Further, a drive current limiting circuit for limiting the current of the switching element and the stator coil is mounted on the circuit board. Further, a thermal element is provided in proximity to or in contact with the switching element of the circuit board, and the drive current limiting circuit is operated by an output signal of the thermal element. Still further, a thermosensitive element is provided near or incorporated in the stator coil, and the drive current limiting circuit is operated by an output signal of the thermosensitive element.

Further, a cut is provided in each of the terminal groups provided in the housing, and the lead terminals of the circuit board are engaged with the cuts and connected by soldering or the like. Further, the circuit board is made of ceramic. Furthermore, a heat radiation means is provided on one surface of the circuit board.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 1 to 3 show a configuration of a stepping motor type flow control device according to a first embodiment of the present invention. FIG. 1 is a sectional view, FIG. 2 is a perspective view, and FIG. 3 is a circuit board on which a drive circuit is mounted. It is a perspective view, and the same code | symbol is attached | subjected to the same part as the above-mentioned conventional example. In the figure, reference numeral 1 denotes a rotor 2 composed of a multi-magnetized permanent magnet 4 and a rotating shaft 5, a stator 3 composed of a stator coil 6 and magnetic poles (not shown), and a housing 7. The stator 3 is held by a housing 7 and the rotor 2 is
Are rotatably supported by a bearing 8 and a sleeve bearing 16 provided on the shaft. 9 is terminal 10
, A signal from an ECU (not shown) and power from a power supply are supplied. Reference numeral 12 denotes a valve body that controls the idling speed by adjusting the intake air amount of the internal combustion engine together with the valve seat 13. The valve body 12 engages with the rotating shaft 5 with a screw portion 14 and the outer peripheral portion is a valve body holding portion of the housing 7. 15 is movable only in the axial direction and is held so as not to rotate.

Reference numeral 17 denotes a circuit board mounted on the housing 7 of the stepping motor 1, and reference numeral 18 denotes a heat sink for radiating heat of the circuit board 17. As shown in FIG. Stator coil 6 and connector 9 of stepping motor 1
The circuit board 17 has a lead terminal 20 electrically connected to and attached to the terminal group 19, and a heat sink 18 is adhesively fixed to one surface. As shown in FIG. 3, on the other surface of the circuit board 17, an electronic component 21 constituting a circuit is mounted on a printed wiring pattern. The electronic component 21 is an amplification circuit for amplifying a signal from the ECU, the ECU.
And a driving current limiting circuit such as a chopper circuit for controlling the current flowing through the switching element and the stator coil by controlling the switching element and the current flowing through the stator coil. A drive circuit is formed.

In the thus configured stepping motor type flow control device according to the first embodiment of the present invention, the control operation of the intake flow rate is the same as that of the above-described conventional example, and the circuit board 17 is controlled by a signal from an ECU (not shown). A switching element of a drive circuit mounted on the controller controls on / off of energization of the stator coil 6 and controls a position of the valve body 12 to control an intake air amount. This switching element is a heating element for controlling a relatively large current, and this heat is radiated by the heat sink 18. However, the heat conduction is improved to enhance the heat radiation effect.
In order to obtain heat resistance, a ceramic substrate is used for the circuit board 17, and an aluminum heat sink is used for the heat sink 18.

The drive current limiting circuit mounted on the circuit board 17 detects the temperature of the stator coil 6 as a heating element and the temperature of the switching element, and if the temperature exceeds a predetermined value, the switching element and the stator coil Is configured to limit the current and suppress heat generation. Further, a U-shaped cut is provided at a tip end of the terminal group 19 which is insert-molded in the housing 7 from the housing 7, and the lead terminals 20 of the circuit board 17 are provided at the same pitch as the terminal group 19, The circuit board 17 is configured to be electrically connected only by attaching the circuit board 17 to the housing 7 of the stepping motor 1 and performing soldering.

In the stepping motor type flow controller according to the first embodiment of the present invention, the drive current is limited when the temperatures of the stator coil 6 and the switching element exceed predetermined values as described above. In a normal state or when the ambient temperature is low, a current determined by the power supply voltage and the resistance value of the stator coil 6 is applied, and the operation becomes frequent or the ambient temperature rises abnormally, and the temperature of the stator coil or the switching element increases. The current value is reduced only when the value exceeds a predetermined value.In normal times, the current is set to a large value, a sufficient ampere turn is obtained, the torque of the stepping motor is increased, and the response of the flow control is improved. In addition, it is possible to prevent burnout of the stator coil and destruction of the switching element due to temperature rise. Since those made possible ECU miniaturization of the standardization and is.

Embodiment 2 FIG. 4 is a perspective view showing a configuration of a circuit board mounted on a stepping motor type flow rate control device according to a second embodiment of the present invention. A thermosensitive element 22 such as a thermistor is provided in the vicinity, in particular, in proximity to or in contact with the switching element. With this configuration, when the temperature of the switching element exceeds a predetermined value, the drive current limiting circuit is operated by the output of the thermosensitive element 22, and the current value is reduced to prevent the destruction of the switching element. it can.

Embodiment 3 FIG. 5 shows a configuration of a stepping motor type flow rate control device according to a third embodiment of the present invention. This embodiment is incorporated in the vicinity of or in the stator coil 6 of the stepping motor. A thermosensitive element 23 such as a thermistor is provided. With this configuration, when the temperature of the stator coil 6 exceeds a predetermined value, the drive current limiting circuit is operated by the output of the thermosensitive element 23, and the current value is reduced to prevent the stator coil 6 from burning. Can be prevented.

[0018]

As described above, according to the stepping motor type flow control device of the present invention, a driving current limiting circuit is added to the driving circuit of the stepping motor to drive the switching element and the stator coil by the temperature. Since the current is limited and the circuit board is integrated with the stepping motor, it is possible to design the switching element and the stator coil to match the heat resistance limit, and to select parts without waste, High performance and reliability can be ensured, for example, by obtaining a high torque during normal operation and controlling the flow rate with good responsiveness, and by limiting the current at high temperatures to prevent burning of the stator coil and destruction of the switching element. It is possible to obtain a possible stepping motor type flow controller.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a stepping motor type flow rate control device according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a stepping motor type flow rate control device according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a circuit board used in the stepping motor type flow controller according to Embodiment 1 of the present invention.

FIG. 4 is a perspective view of a circuit board used in a stepping motor type flow control device according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a configuration of a stepping motor type flow rate control device according to a third embodiment of the present invention.

FIG. 6 is a sectional view of a conventional stepping motor type flow controller.

[Explanation of symbols]

1 Stepping motor, 2 rotors, 3 stators, 4
Permanent magnet, 5 rotating shaft, 6 stator coil, 7 housing, 8, 16 bearing, 9 connector, 10
Terminal, 12 valve body, 13 valve seat, 14 screw part,
15 valve body holder, 17 circuit board, 18 heat sink, 19 terminal group, 20 lead terminal, 21 electronic component, 22, 23 heat-sensitive element.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/20 315 H02K 37/14 535Y H02K 37/14 535 37/24 L 37/24 F02D 33/00 318G H02P 8/14 H02P 8/00 A F term (reference) 3G301 HA01 JA00 JA03 KA07 LA04 LC04 PG00Z PG02Z 3H062 AA02 AA15 BB05 BB15 BB16 BB24 CC02 DD01 EE06 FF34 HH02 HH10 5H580 AA08 BB07 CA02 HH37 JJ

Claims (7)

[Claims] 1. A stepping motor comprising a rotor having a rotating shaft, a stator having a stator coil, and a housing for rotatably supporting the rotor and holding the stator, and rotation of the stepping motor. A flow control valve coupled to and driven by a shaft, a terminal group provided on a housing of the stepping motor and connected to an external terminal and a stator coil, mounted on the housing, electrically connected to the terminal group, and a stator. A stepping motor type flow controller comprising a circuit board on which a switching element for supplying a drive current to a coil is mounted. 2. The stepping motor type flow control device according to claim 1, wherein a drive current limiting circuit for limiting the current of the switching element and the stator coil is mounted on the circuit board. 3. A heat-sensitive element is provided adjacent to or in contact with a switching element on a circuit board, and a drive current limiting circuit is operated by an output signal of the heat-sensitive element. The stepping motor type flow control device according to claim 1 or 2. 4. A heat-sensitive element is provided adjacent to or incorporated in the stator coil, and a drive current limiting circuit is activated by an output signal of the heat-sensitive element. A stepping motor type flow control device according to claim 1 or 2. 5. The terminal group provided in the housing is provided with a notch, and a lead terminal of the circuit board is engaged with the notch and connected by soldering or the like. Item 5. A stepping motor type flow control device according to any one of Items 4. 6. The stepping motor type flow controller according to claim 1, wherein the circuit board is formed of ceramic. 7. The stepping motor type flow control device according to claim 1, wherein a heat radiating means is provided on one surface of the circuit board.