Valve device and system in which the valve device is mounted

A valve device that includes a valve body; a valve shaft configured to rotate the valve body; a coil spring being electrically conductive and configured to be twisted with rotation of the valve body and the valve shaft; a first conductive member being electrically conductive and facing an inner circumferential surface or an outer circumferential surface of the coil spring in a radial direction of the coil spring; and a first detector configured to detect at least one of a rotation angle of the valve body or a rotation angle of the valve shaft based on an electrostatic capacitance between the coil spring and the first conductive member, the electrostatic capacitance changing according to a state of the coil spring that changes with the rotation of the valve body and the valve shaft.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2019-204893, filed on Nov. 12, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a valve device and a system in which the valve device is mounted.

BACKGROUND

Japanese Patent Application Publication No. 2019-124527 describes a throttle valve. The throttle valve of Japanese Patent Application Publication No. 2019-124527 includes a rotary body and a coil spring (return spring) configured to be twisted with rotation of the rotary body. Japanese Patent Application Publication No. 2019-124527 further describes a rotation angle detector. The rotation angle detector described in Japanese Patent Application Publication No. 2019-124527 includes a rotary body, a rotor disposed coaxially with the rotary body, a rotary conductive member disposed coaxially with the rotor at one end of the rotor, a fixed conductive member disposed to face the rotary conductive member, and an electronic circuit configured to detect a rotation position of the rotary body based on a change in an inductance between the rotary conductive member and the fixed conductive member according to a position of the rotary conductive member in its rotation direction.

SUMMARY

In the technique of Japanese Patent Application Publication No. 2019-124527, the rotary conductive member and the fixed conductive member need to be disposed to detect the rotation position of the rotary body, which may cause the rotation angle detector to become oversized and complicated. In view of this, the disclosure herein provides art that enables a valve device to determine a rotation angle while preventing the valve device from becoming oversized and complicated.

A valve device disclosed herein may comprise: a valve body; a valve shaft configured to rotate the valve body; a coil spring being electrically conductive and configured to be twisted with rotation of the valve body and the valve shaft; a first conductive member being electrically conductive and facing an inner circumferential surface or an outer circumferential surface of the coil spring in a radial direction of the coil spring; and a first detector configured to detect at least one of a rotation angle of the valve body or a rotation angle of the valve shaft based on an electrostatic capacitance between the coil spring and the first conductive member, the electrostatic capacitance changing according to a state of the coil spring that changes with the rotation of the valve body and the valve shaft.

This configuration enables detection of at least one of the rotation angle of the valve body or the rotation angle of the valve shaft by using a change in the electrostatic capacitance between the coil spring and the first conductive member in response to rotation of the valve body and the valve shaft. In realizing the configuration for determining the rotation angle in the valve device, the above configuration enables detection of the rotation angle by using the coil spring that is twisted with the rotation of the valve body and the valve shaft without any additional configurations such as a rotary conductive member and a fixed conductive member as in the conventional technique. This can prevent the valve device from becoming oversized and complicated.

The first conductive member may define a circumferential wall extending in an axial direction of the valve shaft. The circumferential wall may face the coil spring over a whole area from one end to another end of the coil spring in an axial direction of the coil spring.

In this configuration, the coil spring and the first conductive member face each other over a large area. Due to this, the electrostatic capacitance between the coil spring and the first conductive member greatly changes when the valve body and the valve shaft rotate. This can ensure that an output value required for determining at least one of the rotation angle of the valve body or the rotation angle of the valve shaft is outputted.

The present disclosure discloses a system in which the above valve device may be mounted. The system may comprise two power sources. The valve device may further comprise a motor configured to be operated by direct current and rotate the valve shaft. One of the two power sources may be configured to apply a voltage to the motor and another of the two power sources may be configured to apply a voltage to at least one of the coil spring or the first conductive member to generate a potential difference between the coil spring and the first conductive member.

This configuration can provide increased accuracy for the detection of the rotation angle.

Another valve device disclosed herein may comprise: a valve body; a valve shaft configured to rotate the valve body; a coil spring being electrically conductive and configured to be twisted with rotation of the valve body and the valve shaft; and a second detector configured to detect at least one of a rotation angle of the valve body or a rotation angle of the valve shaft based on an inductance of the coil spring, the inductance changing according to a state of the coil spring that changes with the rotation of the valve body and the valve shaft.

This configuration enables detection of at least one of the rotation angle of the valve body or the rotation angle of the valve shaft by using a change in the inductance of the coil spring in response to rotation of the valve body and the valve shaft. In realizing the configuration for determining the rotation angle in the valve device, the above configuration enables detection of the rotation angle by using the coil spring that is twisted with the rotation of the valve body and the valve shaft without any additional configurations such as the rotary conductive member and the fixed conductive member as in the conventional technique. This can prevent the valve device from becoming oversized and complicated.

The valve device may further comprise at least one second conductive member being electrically conductive and arranged on at least one of: an inner side relative to an inner circumferential surface of the coil spring or an outer side relative to an outer circumferential surface of the coil spring in a radial direction of the coil spring.

In this configuration, the at least one second conductive member functions as a core of the coil spring, which can ensure that the output value for determining at least one of the rotation angle of the valve body or the rotation angle of the valve shaft is outputted.

The at least one second conductive member may define a circumferential wall extending in an axial direction of the valve shaft. The circumferential wall may face the coil spring over a whole area from one end to another end of the coil spring in an axial direction of the coil spring.

In this configuration, the coil spring and the at least one second conductive member face each other over a large area. Due to this, the electrostatic capacitance between the coil spring and the at least one second conductive member greatly changes when the valve body and the valve shaft rotate. This can ensure that the output value for determining at least one of the rotation angle of the valve body or the rotation angle of the valve shaft is outputted.

The present disclosure discloses a system in which the other valve device may be mounted. The system may comprise two power sources. The valve device may further comprise a motor configured to be operated by direct current and to rotate the valve shaft. One of the two power sources may be configured to apply a voltage to the motor and another of the two power sources may be configured to apply a voltage to at least one of the coil spring or the at least one second conductive member to generate a potential difference between the coil spring and the at least one second conductive member.

This configuration can provide increased accuracy for the detection of the rotation angle.

DETAILED DESCRIPTION

First Embodiment

A valve device2of a first embodiment will be described. As shown inFIG. 1, the valve device2includes a casing10, a valve body30, and a motor50. The valve device2shown inFIG. 1is, for example, mounted on an automobile with an engine. The valve device2is, for example, disposed on an intake passage through which air to be suctioned into the engine of the automobile flows. The valve device2is used to control a flow rate of the air flowing through the intake passage. The valve device2may be called a throttle valve.

The casing10of the valve device2includes a housing unit12and a passage unit11. The housing unit12houses a first gear41, a plurality of second gears42, the motor50, and a coil spring20to be described later. The passage unit11of the casing10constitutes a part of the intake passage through which the air to be suctioned into the engine of the automobile flows. The passage unit11has a substantially cylindrical shape. The air flows along an axial direction of the cylindrical passage unit11(direction perpendicular to a sheet surface ofFIG. 1). The valve body30is disposed inside the passage unit11.

The valve body30has a substantially disk shape. The valve body30is fixed to a valve shaft31. The valve shaft31extends in a radial direction of the passage unit11(direction orthogonal to the axial direction of the passage unit11). The valve shaft31is supported rotatably by a bearing32fixed to the casing10. The valve body30rotates with rotation of the valve shaft31. The valve body30changes a cross-sectional area inside the passage unit11(passage area of the intake passage) by rotating inside the passage unit11. The change in the passage area of the intake passage changes the flow rate of the air flowing through the intake passage. For example, when the valve body30rotates forward, the passage area increases and the air flow rate increases. Further, when the valve body30rotates in reverse, the passage area decreases and the air flow rate decreases. The air flow rate changes based on a rotation angle of the valve body30.

The first gear41is fixed to an end33of the valve shaft31. The first gear41is mechanically connected to a rotary shaft51of the motor50via the plurality of second gears42. When the rotary shaft51of the motor50rotates, the second gears42and the first gear41rotate. When the first gear41rotates, the valve shaft31and the valve body30rotate. The motor50is configured to be operated by direct current and rotate the valve shaft31.

As shown inFIGS. 2 and 3, the first gear41includes a shaft portion61, an inner guide62(example of a first conductive member), and a gear63. The first gear41is constituted of a conductor such as metal or conductive resin. The conductor is electrically conductive. The shaft portion61is fixed to the valve shaft31via a fastener65. The inner guide62is fixed to the shaft portion61. The gear63is fixed to the inner guide62. The gear63of the first gear41is connected to the rotary shaft51of the motor50via the plurality of second gears42(seeFIG. 1).

The inner guide62of the first gear41is disposed around the valve shaft31. The inner guide62has a substantially cylindrical shape. The inner guide62surrounds the valve shaft31. The inner guide62is disposed coaxially with the valve shaft31. The inner guide62extends in an axial direction of the valve shaft31. A portion of the inner guide62facing the coil spring20is constituted as a conductive member. The coil spring20is disposed around the inner guide62. The inner guide62faces an inner circumferential surface24of the coil spring20over an area from one end to the other end of the coil spring20in an axial direction of the coil spring20. The inner guide62faces the inner circumferential surface24of the coil spring20over a whole area of the coil spring20in the axial direction. In other words, the inner guide62defines a circumferential wall extending in the axial direction of the valve shaft31. The circumferential wall (inner guide62) is disposed to face the coil spring20over the whole area of the coil spring20from its one end to the other end in the axial direction.

The coil spring20is wound around the inner guide62. The coil spring20surrounds the valve shaft31and the inner guide62. The coil spring20is disposed coaxially with the valve shaft31and the inner guide62. The coil spring20is constituted of a conductor such as metal or conductive resin. The conductor is electrically conductive. The coil spring20is configured of a wound conductor wire. The inner circumferential surface24of the coil spring20faces an outer circumferential surface64of the inner guide62in a radial direction of the coil spring20. The inner circumferential surface24of the coil spring20is at a position separated from the outer circumferential surface64of the inner guide62. A clearance is defined between the inner circumferential surface24of the coil spring20and the outer circumferential surface64of the inner guide62. The coil spring20being the conductive member and the inner guide62being the conductive member constitute a capacitor by facing each other.

As shown inFIG. 4, the coil spring20includes a fixed abutment portion21and a rotary abutment portion22. The fixed abutment portion21is disposed at one end of the coil spring20and the rotary abutment portion22is disposed at the other end thereof. The fixed abutment portion21abuts a first abutment portion71. The first abutment portion71is disposed on an inner surface of the casing10housing the coil spring20(not shown). Forward rotation of the coil spring20(for example, counter-clockwise rotation) is restricted by the fixed abutment portion21coming into abutment with the first abutment portion71.

The rotary abutment portion22at the other end of the coil spring20abuts a second abutment portion72. The second abutment portion72is disposed on an outer surface of the first gear41housed in the casing10(not shown). Reverse rotation of the coil spring20(for example, clockwise rotation) is restricted by the rotary abutment portion22coming into abutment with the second abutment portion72. When the first gear41rotates forward, the rotary abutment portion22comes into abutment with the second abutment portion72.

When the first gear41rotates, the coil spring20is thereby twisted. When the first gear41rotates forward, the coil spring20is twisted in a forward rotation direction (for example, counter-clockwise). When the first gear41rotates in reverse, this twist in the coil spring20is released. When the coil spring20is twisted, a diameter of the coil spring20decreases. When the diameter of the coil spring20decreases, a distance H between the inner circumferential surface24of the coil spring20and the outer circumferential surface64of the inner guide62becomes shorter (seeFIG. 3). Further, when the coil spring20is twisted, a length L of the coil spring20in the axial direction becomes longer. When the length L of the coil spring20in the axial direction becomes longer, the area over which the inner circumferential surface24of the coil spring20faces the outer circumferential surface64of the inner guide62becomes larger.

As shown inFIG. 3, the valve device2includes a CV circuit80and an engine control unit (ECU)100.

The CV circuit80is connected to the coil spring20and the inner guide62of the first gear41. The CV circuit80is a circuit configured to output a voltage value depending on an electrostatic capacitance of a capacitor to which the CV circuit80is connected. The electrostatic capacitance of a capacitor is generally proportional to an area over which a pair of conductive members faces each other, and is inversely proportional to a distance between this pair of conductive members. The coil spring20and the inner guide62of the valve device2constitute a capacitor. The CV circuit80outputs a voltage value depending on the electrostatic capacitance between the coil spring20and the inner guide62(that is, the electrostatic capacitance of the capacitor). Since the CV circuit80is incorporated in a known CV converter, a detailed description thereof will be omitted.

The ECU100is configured to execute processes and control related to the valve device2. The ECU100includes a memory120. The ECU100is configured to determine the rotation angle of the first gear41, the valve shaft31, and the valve body30based on the voltage value outputted from the CV circuit80. As shown inFIG. 5, the ECU100stores, in advance in the memory120, a graph T indicating a relationship between the voltage value and the rotation angle of the first gear41, the valve shaft31, and the valve body30. The ECU100uses the graph T stored in the memory120to determine the rotation angle of the first gear41, the valve shaft31, and the valve body30based on the voltage value outputted from the CV circuit80. The graph T is obtained in advance by experiments and/or analyses. For example, the graph T is created in advance by determining a relationship between the rotation angle exhibited when the first gear41, the valve shaft31, and the valve body30rotate and the voltage value outputted from the CV circuit80in response to the rotation thereof by experiments. The graph T created as such is stored in the memory120.

Next, an operation of the valve device2will be described. In the valve device2as above, the first gear41, the valve shaft31, and the valve body30rotate (forward or in reverse) when the rotary shaft51of the motor50rotates (forward or in reverse).

When the first gear41, the valve shaft31, and the valve body30rotate forward, the coil spring20is thereby twisted circumferentially in the forward rotation direction. When the coil spring20is twisted in the forward rotation direction, the diameter of the coil spring20decreases. That is, the inner circumferential surface24of the coil spring20approaches the outer circumferential surface64of the inner guide62, by which the distance H between the coil spring20and the inner guide62becomes shorter. As a result, the electrostatic capacitance between the coil spring20and the inner guide62becomes larger. Further, when the coil spring20is twisted in the forward rotation direction, the length L of the coil spring20in the axial direction becomes longer. That is, the area over which the inner circumferential surface24of the coil spring20faces the outer circumferential surface64of the inner guide62increases. As a result, the electrostatic capacitance between the coil spring20and the inner guide62becomes larger. The larger the rotation angle of the first gear41, the valve shaft31, and the valve body30is, the larger the electrostatic capacitance between the coil spring20and the inner guide62becomes.

When the first gear41, the valve shaft31, and the valve body30rotate in reverse, the twist of the coil spring20is released. When the twist of the coil spring20is released, the diameter of the coil spring20becomes larger. That is, the inner circumferential surface24of the coil spring20moves away from the outer circumferential surface64of the inner guide62, by which the distance H between the coil spring20and the inner guide62becomes longer. As a result, the electrostatic capacitance between the coil spring20and the inner guide62becomes smaller. Further, when the twist of the coil spring20is released, the length L of the coil spring20in the axial direction becomes shorter. That is, the area over which the inner circumferential surface24of the coil spring20faces the outer circumferential surface64of the inner guide62decreases. As a result, the electrostatic capacitance between the coil spring20and the inner guide62becomes smaller.

The ECU100determines the rotation angle of the valve body30and the valve shaft31based on the electrostatic capacitance that changes between the coil spring20and the inner guide62in response to the rotation of the valve body30and the valve shaft31. More specifically, the CV circuit80connected to the coil spring20and the inner guide62outputs a voltage value depending on the electrostatic capacitance between the coil spring20and the inner guide62when the coil spring20is not twisted or the electrostatic capacitance therebetween when the coil spring20is twisted. Then, based on the voltage value outputted from the CV circuit80, the ECU100determines the rotation angle of the first gear41, the valve shaft31, and the valve body30. The ECU100determines the rotation angle of the first gear41, the valve shaft31, and the valve body30according to the graph T (seeFIG. 5) stored in the memory120. Due to this, the ECU100corresponds to a first detector.

The valve device2of the first embodiment has been described above. As it is apparent from the above disclosure, the valve device2includes the coil spring20configured to be twisted with the rotation of the first gear41, the valve shaft31, and the valve body30, and the inner guide62being the conductive member that faces the inner circumferential surface24of the coil spring20in the radial direction of the coil spring20. Further, the valve device2includes the ECU100configured to determine the rotation angle of the first gear41, the valve shaft31, and the valve body30based on the voltage value depending on the electrostatic capacitance between the coil spring20and the inner guide62exhibited when the coil spring20is twisted with the rotation of the first gear41, the valve shaft31, and the valve body30.

This configuration enables the determination of the rotation angle of the first gear41, the valve shaft31, and the valve body30by using the existing configuration. That is, the configuration can provide the function of detecting the rotation angle to the valve device2while preventing the valve device2from becoming oversized and complicated.

In the above valve device2, the inner guide62is disposed to face the coil spring20over the whole area from the one end to the other end of the coil spring20in the axial direction of the coil spring20. In this configuration, the area over which the coil spring20faces the inner guide62is large. As such, the electrostatic capacitance between the coil spring20and the inner guide62greatly changes upon when the coil spring20is twisted, by which accuracy for determining the rotation angle can be increased.

One embodiment has been described above, however, specific aspects are not limited to the above embodiment. In the description below, the same reference signs will be given to configurations identical to those in the foregoing disclosure, and description thereof will be omitted.

Second Embodiment

As shown inFIG. 6, a valve device2of a second embodiment includes an LV circuit90instead of the CV circuit80. The LV circuit90is connected to the one and the other ends of the coil spring20in the axial direction. The LV circuit90is a circuit configured to output a voltage value depending on an inductance of a coil to which the LV circuit90is connected. The inductance of a coil is generally proportional to the square of the number of turns of the coil. The LV circuit90outputs a voltage value depending on an inductance of the coil spring20. The ECU100is configured to determine the rotation angle of the first gear41, the valve shaft31, and the valve body30based on the voltage value outputted from the LV circuit90. Since the LV circuit90is incorporated in a known LV converter, a detailed description thereof will be omitted.

In the valve device2of the second embodiment, when the first gear41, the valve shaft31, and the valve body30rotate forward, the coil spring20is thereby circumferentially twisted in the forward rotation direction. When the coil spring20is twisted in the forward rotation direction, the number of turns of the coil spring20increases. When the number of turns of the coil spring20increases, the inductance of the coil spring20becomes larger proportional to the square of the number of turns. The larger the rotation angle of the first gear41, the valve shaft31, and the valve body30is, the larger the inductance of the coil spring20becomes.

As such, the ECU100determines the rotation angle of the valve body30and the valve shaft31based on the inductance of the coil spring20that changes with the rotation of the valve body30and the valve shaft31. More specifically, the LV circuit90connected to the coil spring20outputs a voltage value depending on the inductance of the coil spring20when the coil spring20is not twisted or the inductance of the coil spring20when the coil spring20is twisted. Further, the ECU100determines the rotation angle of the first gear41, the valve shaft31, and the valve body30based on the voltage value outputted from the LV circuit90. The ECU100determines the rotation angle of the first gear41, the valve shaft31, and the valve body30based on the graph T (seeFIG. 5) stored in the memory120. Due to this, the ECU100corresponds to a second detector.

The second embodiment has been described above. As it is apparent from the above description, the valve device2of the second embodiment can determine the rotation angle of the first gear41, the valve shaft31, and the valve body30by using the existing configuration. That is, the function of detecting the rotation angle can be provided to the valve device2, while the valve device2is prevented from becoming oversized and complicated.

Further, the above valve device2includes the inner guide62(an example of a second conductive member) arranged on an inner side relative to the inner circumferential surface24of the coil spring20in the radial direction of the coil spring20. The inner guide62functions as a core of the coil. This configuration ensures that the output value for determining the rotation angle is outputted.

Other Embodiments

(1) In another embodiment, the inner guide62of the first gear41may not face the inner circumferential surface24of the coil spring20over the area from the one end to the other end of the coil spring20in the axial direction. The inner guide62may not face the inner circumferential surface24of the coil spring20over the whole area of the coil spring20in the axial direction. The inner guide62may face at least a part of the inner circumferential surface24of the coil spring20.

(2) In another embodiment, metal plating may be applied on the outer circumferential surface64of the inner guide62of the first gear41. The outer circumferential surface64of the inner guide62may be coated by a metal film. Alternatively, the outer circumferential surface64of the inner guide62may be covered by a metal plate. The metal film or the metal plate may be another example of the first conductive member. In this configuration, the capacitor is constituted of the coil spring20and one of the metal film and the metal plate.

(3) In the first embodiment as above, the inner guide62facing the inner circumferential surface24of the coil spring20is an example of the first conductive member, however, no limitation is made to this configuration. In another embodiment, as shown inFIG. 7, the valve device2may include an outer guide66facing an outer circumferential surface25of the coil spring20. The outer guide66is constituted of a conductor such as metal or conductive resin. The outer guide66may be another example of the first conductive member. The capacitor may be constituted of the coil spring20and the outer guide66. The outer circumferential surface25of the coil spring20and an inner circumferential surface67of the outer guide66face each other. The CV circuit80is connected to the coil spring20and the outer guide66(not shown). The CV circuit80outputs a voltage value depending on an electrostatic capacitance between the coil spring20and the outer guide66. This configuration can ensure that the output value for determining the rotation angle is outputted with a simple configuration, as well. Only a portion of the outer guide66facing the coil spring20may be constituted of a conductor such as metal or conductive resin.

(4) In the second embodiment as above, the inner guide62facing the inner circumferential surface24of the coil spring20is an example of the second conductive member, however, no limitation is made to this configuration. In another embodiment, the outer guide66facing the outer circumferential surface25of the coil spring20may be an example of the second conductive member. One of the inner guide62and the outer guide66may be an example of the second conductive member. Further, both the inner guide62and the outer guide66may be examples of the second conductive member.

(5) In the above embodiments, the ECU100determines the rotation angle of the first gear41, the valve shaft31, and the valve body30according to the graph T stored in the memory120, however, no limitation is made to this configuration. In another embodiment, the ECU100may determine the rotation angle of the first gear41, the valve shaft31, and the valve body30according to a predetermined conversion equation. Similar to the graph T, the predetermined conversion equation indicates a relationship between the voltage value and the rotation angle.

(6) In the above embodiments, the valve device2is employed in the automobile, however, no limitation is made to this configuration. In another embodiment, the valve device2may be employed in machines or devices other than automobiles.

(7) In another embodiment, the valve device2may include, instead of the CV circuit80, a circuit (not shown) configured to output a value of the electrostatic capacitance between the coil spring20and the inner guide62when the coil spring20is twisted. The ECU100may determine the rotation angle of the first gear41, the valve shaft31, and the valve body30based on this value of the electrostatic capacitance outputted from this circuit. That is, the ECU100may obtain the electrostatic capacitance between the coil spring20and the inner guide62from the circuit, and may detect the rotation angle from the obtained electrostatic capacitance.

(8) In another embodiment, in a case where a system including the valve device2includes two or more power sources, one of the power sources (one power source) may apply a voltage to the motor50and the other of the power sources (the other power source) may apply a voltage to the coil spring20or the inner guide62to generate a potential difference between them. For example, the coil spring20may be connected to the other power source and the inner guide62may be connected to the ground. Alternatively, the coil spring20may be connected to the ground and the inner guide62may be connected to the other power source. In this configuration, motor noise does not affect the detection of the rotation angle, thus accuracy for the detection of the rotation angle can be increased.

(9) In a variant of the first embodiment, the ECU100may include the function of the CV circuit80. In this case, the CV circuit80may be omitted. Similarly, in a variant of the second embodiment, the ECU100may include the function of the LV circuit90. In this case, the LV circuit90may be omitted.