1. A flow regulating valve (1A) comprising: a body (10) that has a fluid passage through which a fluid passes; a disc (21) that opens and closes the fluid passage; a stem (22) that is rotatably supported by the body (10) and coupled to the disc (21); and an AC servomotor (40) that includes an output shaft (41) connected to the stem (22), wherein the output shaft (41) of the AC servomotor (40) is rotated while an opening degree of the disc (21) is detected by an opening degree sensor to change the opening degree of the disc (21) via the stem (22) and regulate a flow rate of the fluid, and the opening degree sensor is an angular position sensor (50) attached to the AC servomotor (40) and no opening degree sensor is provided on a side of the disc (21) or the stem (22).

2. The flow regulating valve (1A) according to claim 1, wherein a gear (61, 71, 72, 81) is interposed between the output shaft (41) and the stem (22), and the flow rate of the fluid is regulated while the opening degree of the disc (21) is estimated by multiplying an angular position detected by the angular position sensor (50) by a coefficient corresponding to a ratio of rotation between the output shaft (41) and the stem (22).

3. A flow control device attached to or connected to the flow regulating valve (1A) according to claim 2, wherein The flow control device receives input of detection data by the angular position sensor (50), performs drive operation of the AC servomotor (40), and controls the flow regulating valve (1A) while estimating an opening degree of the disc (21) by multiplying the angular position detected by the angular position sensor (50) by a coefficient corresponding to a ratio of rotation between the output shaft (41) and the stem (22).

Description:BACKGROUND
TECHNICAL FIELD
[0001]
The present invention relates to a flow regulating valve and a flow control device using the same, and in particular to a flow regulating valve that performs a precise opening and closing operation of a disc using an AC servomotor, and a flow control device connected to the flow regulating valve and using the flow regulating valve for control.

RELATED ART
[0002]
A flow regulating valve adopting a system of precisely opening and closing a valve for regulating the flow rate of a fluid such as air or exhaust gas of an engine by driving an electric motor such as a DC motor or a stepping motor is known. For example, as in a flow regulating valve 1B including a DC motor 40B illustrated in FIG. 6, in order to detect a valve opening degree that is an opening angle of a disc 21, an opening degree sensor (angular position sensor) 31 and a detection magnet 32 are typically disposed on an axis of a stem 22 coupled to the disc 21.
[0003]
As the opening degree sensor, various types are used such as a contact type (resistance type) and a non-contact type (magnetic force type). However, opening degree sensors of any type need to include various components for detecting the opening degree of the disc, and this need is one factor that makes it difficult to reduce the size and cost of the flow regulating valve.
[0004]
In addition, it is also known to use an AC servomotor capable of accurately controlling the angular position of its output shaft that corresponds to the motor rotation state as an electric motor used as a driving means of the disc of the flow regulating valve.
[0005]
For example, as in a flow regulating valve 1C including an AC servomotor 40C illustrated in FIG. 7, the AC servomotor 40C typically includes an output shaft 41, a rotor 42 and a stator 43 disposed around the output shaft 41, and an angular position sensor 50 that detects an angular position at which the output shaft 41 has rotated. Since the flow regulating valve 1C includes two sensors that are the angular position sensor (encoder) 50 on the output side that detects the rotation angle of the output shaft 41 and an opening degree sensor 31 on the side of the disc 21 that detects the rotation angle of the stem 22 as the opening degree of the disc 21, the number of parts is increased, leading to a complicated structure and an increase in product cost.
[0006]
As in the above-described flow regulating valves 1B and 1C and the invention described in, for example, JP H06-93888 A, gears 61, 71, 72, and 81 for converting rotation speed and the like are typically interposed between the output shaft of the motor and the stem of the disc (see FIGS. 6 and 7), and the angle detected by the opening degree sensor 31 on the side of the disc 21 and the angle detected by the angular position sensor 50 on the output side do not coincide with each other. Therefore, it is not possible to execute the drive control of the motor using the detection data by the opening degree sensor 31 as it is.

SUMMARY
[0008]
An object of the present invention is to solve the above problem, and to enable highly accurate flow control with a simple configuration for a flow regulating valve that performs control while regulating the flow rate of a fluid.
[0009]
The present invention made to solve the above problems is a flow regulating valve including: a body that has a fluid passage through which a fluid passes; a disc that opens and closes the fluid passage; a stem that is rotatably supported by the body and coupled to the disc; and an AC servomotor that includes an output shaft connected to the stem, in which the output shaft of the AC servomotor is rotated while an opening degree of the disc is detected by an opening degree sensor to change the opening degree of the disc via the stem and regulate a flow rate of the fluid, and the opening degree sensor is an angular position sensor attached to the AC servomotor, and no opening degree sensor is provided on a side of the disc or the stem.
[0010]
As described above, since the detection data by the angular position sensor attached to the AC servomotor included in the flow regulating valve is used as the data for detecting the opening degree (valve angle) of the disc for the opening and closing control of the disc, the flow regulating valve includes no opening degree sensor on the side of the disc or the stem. This configuration enables highly accurate flow control with a simple configuration, and can make the product compact.
[0011]
In the present invention, a gear is interposed between the output shaft and the stem. When the flow rate of the fluid is regulated while the opening degree of the disc is estimated by multiplying an angular position detected by the angular position sensor by a coefficient corresponding to a ratio of rotation between the output shaft and the stem, it is possible to accurately control the flow regulating valve while accurately detecting the opening degree of the disc without imposing an excessive processing load on a control device that controls the flow regulating valve.
[0012]
Furthermore, a flow control device according to the present invention using the flow regulating valve is attached to or connected to the flow regulating valve, receives input of detection data by the angular position sensor, performs drive operation of the AC servomotor, and controls opening and closing of the flow regulating valve while estimating an opening degree of the disc by multiplying the angular position detected by the angular position sensor by a coefficient corresponding to a ratio of rotation between the output shaft and the stem, so that precise control can be automatically performed without applying manual operation or the like.
[0013]
According to the present invention in which the detection data by the angular position sensor of the AC servomotor is used for the opening and closing control of the disc, and no opening degree sensor is provided on the side of the disc or the stem, a highly accurate flow control can be performed with a simple configuration, and the product can be made compact.

BRIEF DESCRIPTION OF DRAWINGS
[0014]
FIG. 1 is a sectional view of a flow regulating valve according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating a connection state between an upper gear of intermediate gears and a pinion gear in a state where a lid member is removed in the flow regulating valve illustrated in FIG. 1;
FIG. 3 is a diagram illustrating a connection state between a lower gear of the intermediate gears and a drive gear in a state where the lid member is removed in the flow regulating valve illustrated in FIG. 1;
FIG. 4 is a diagram for explaining a connection state between the pinion gear, the intermediate gears, and the drive gear of the flow regulating valve illustrated in FIG. 1;
FIG. 5 is a graph illustrating an example of a relation between an angular position of an output shaft of an AC servomotor and an angular position of a stem in the flow regulating valve of FIG. 1;
FIG. 6 is a sectional view illustrating an example of a conventional flow regulating valve including a DC motor; and
FIG. 7 is a sectional view illustrating an example of a conventional flow regulating valve including an AC servomotor.

DETAILED DESCRIPTION
[0015]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a sectional view illustrating a flow regulating valve 1A according to the present embodiment. The flow regulating valve 1A includes a body 10 that has a fluid passage 11 through which a fluid passes, a disc 21 that opens and closes the fluid passage 11, a stem 22 that is rotatably supported by the body 10 and coupled to the disc 21, and an AC servomotor 40 including an output shaft 41 connected to the stem 22, and is used to perform control by regulating the flow rate of the fluid such as air or exhaust gas in an engine or the like. An electronic control device (flow control device) (not illustrated) precisely controls opening and closing of the disc 21 disposed in the fluid passage 11 while operating the AC servomotor 40.
[0017]
That is, the flow regulating valve 1A has a structure in which the output shaft 41 of the AC servomotor 40 is rotated while an opening degree (angular position) of the disc 21 is detected by an opening degree sensor and the stem 22 connected via a pinion gear (gear 61), intermediate gears (gears 71 and 72), and a drive gear (gear 81) is rotated, and the disc 21 is rotated and the opening degree is regulated to control the flow rate of the fluid.
[0018]
As the opening degree sensor that detects the opening degree (angular position) of the disc 21, unlike the conventional flow regulating valves 1B and 1C illustrated in FIGS. 6 and 7, the detection magnet 32 and the opening degree sensor (angular position sensor) disposed on the side of the stem 22 are not used, but the angular position sensor 50 attached to the AC servomotor 40 in advance also serves as the opening degree sensor, and no opening degree sensor is provided on the side of the disc 21 or the stem 22. This point is the largest feature of the present invention.
[0019]
As described above, the detection data transmitted by the angular position sensor 50 that is provided in advance as an encoder in the AC servomotor 40 of the flow regulating valve 1A and detects the angular position by the rotation of the output shaft 41 is used as data for detecting the opening degree (valve angle) of the disc 21 for the opening and closing control of the disc 21. Unlike the conventional example, by adopting the configuration in which no opening degree sensor is provided on the side of the disc 21 or the stem 22, it is possible to reduce the height of a lid 12 as compared with the conventional flow regulating valves 1B and 1C. This enables highly accurate flow control with a simple configuration at low cost while keeping the size of the device compact.
[0020]
As the encoder used for the angular position sensor 50, for example, an optical type, a magnetic type, or the like is known, and as the angular position sensor 50 in the present embodiment, any type of encoder among conventionally known encoders can be used.
[0021]
As illustrated in FIGS. 2 to 4, in the flow regulating valve 1A, the gears 61, 71, 72, and 81 are interposed between the output shaft 41 of the AC servomotor 40 and the stem 22, and the angular position of the output shaft 41 by the drive of the AC servomotor 40 detected by the angular position sensor 50 does not necessarily coincide with the angular position of the stem 22 or the opening degree (valve angle) of the disc 21.
[0022]
Thus, in the present embodiment, a system is adopted in which the angular position detected by the angular position sensor 50 is multiplied by a coefficient corresponding to the ratio of rotation between the output shaft 41 and the stem 22 to regulate the flow rate while estimating the opening degree of the disc 21.
[0023]
The graph of FIG. 5 illustrates the relation between the angular position of the output shaft 41 of the AC servomotor 40 and the angular position of the stem 22 in the flow regulating valve 1A, and is obtained by multiplying the angle of the disc 21 in the fully open state by the ratio (B/A) of the number of teeth of the gears 71 and 61 and the ratio (D/C) of the number of teeth of the gears 81 and 72.
[0024]
That is, the power of the gear 61, which is the pinion gear attached to the output shaft 41 of the AC servomotor 40, is transmitted to and drives the gear 81, which is the drive gear attached to the stem 22 to which the disc 21 is fixed, via the gears 71 and 72, which are two-stage gear-shaped intermediate gears disposed therebetween. Since the gear ratio between the pinion gear (the gear 61) and the drive gear (the gear 81) is the ratio of rotation between the AC servomotor 40 and the disc 21, it is possible to control the flow regulating valve 1A by estimating an angle (valve angle) of the disc 21 from angular position data detected by the angular position sensor 50 for operating the AC servomotor 40.
[0025]
The above-described control procedure is actually executed by an electronic control device (flow control device) (not illustrated) connected to the flow regulating valve 1A, and is a method of performing drive control of the AC servomotor 40 by feedback control on the basis of angular position data continuously detected by the angular position sensor 50. It is assumed that, for example, a control device (ECU) or the like that performs drive control of the engine also serves as such an electronic control device, and the above-described control procedure is stored as a control program in a storage unit of the electronic control device.
[0026]
In the present embodiment described above, the electronic control device (flow control device) can precisely control the flow regulating valve 1A while accurately detecting (estimating) the opening degree of the disc 21 without having an excessive processing load in controlling the flow regulating valve 1A.
[0027]
The electronic control device (flow control device) may be included in the flow regulating valve 1A (not illustrated). In this case, the flow regulating valve 1A can be controlled without including an additional circuit in or imposing excessive processing load on a control device (ECU) that performs drive control of the engine.
[0028]
As described above, according to the present invention, the flow regulating valve for performing control by regulating the flow rate of the fluid can perform highly accurate flow control with a simple configuration, and the product can be made compact.
, Claims:1. A flow regulating valve (1A) comprising:
a body (10) that has a fluid passage through which a fluid passes;
a disc (21) that opens and closes the fluid passage;
a stem (22) that is rotatably supported by the body (10) and coupled to the disc (21); and
an AC servomotor (40) that includes an output shaft (41) connected to the stem (22), wherein
the output shaft (41) of the AC servomotor (40) is rotated while an opening degree of the disc (21) is detected by an opening degree sensor to change the opening degree of the disc (21) via the stem (22) and regulate a flow rate of the fluid, and
the opening degree sensor is an angular position sensor (50) attached to the AC servomotor (40) and no opening degree sensor is provided on a side of the disc (21) or the stem (22).

2. The flow regulating valve (1A) according to claim 1, wherein
a gear (61, 71, 72, 81) is interposed between the output shaft (41) and the stem (22), and
the flow rate of the fluid is regulated while the opening degree of the disc (21) is estimated by multiplying an angular position detected by the angular position sensor (50) by a coefficient corresponding to a ratio of rotation between the output shaft (41) and the stem (22).

3. A flow control device attached to or connected to the flow regulating valve (1A) according to claim 2, wherein
The flow control device receives input of detection data by the angular position sensor (50), performs drive operation of the AC servomotor (40), and controls the flow regulating valve (1A) while estimating an opening degree of the disc (21) by multiplying the angular position detected by the angular position sensor (50) by a coefficient corresponding to a ratio of rotation between the output shaft (41) and the stem (22).