JP2017057741A - Valve device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress, in a valve device in which a valve element is driven by an electric motor having a rated voltage lower than a nominal voltage of a battery, ripples of a current flowing through the electric motor.SOLUTION: A valve device 1 comprises a valve element 3 opening and closing an EGR flow passage 2, an electric motor 5 generating driving force for driving the valve element 3, and a control part 6 controlling application of a voltage to the electric motor 5. The electric motor 5 generates driving force by being supplied with electric power from a battery 29 which has a nominal voltage higher than the own rated voltage, and the control part 6 calculates a duty ratio based on the operation state of an internal combustion engine and outputs a signal for turning-on/off the application of a voltage to the electric motor 5 based on the calculated duty ratio. A period for turning on the application of a voltage to the electric motor 5 is shorter than a period for calculation of a duty ratio by the control part 6. The frequency of the on-off signal therefore can be increased, so that ripples of a current flowing through the electric motor 5 can be suppressed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a valve device incorporated in an intake / exhaust system of an internal combustion engine.

  Conventionally, in the above valve device, a valve body that opens and closes a flow path that constitutes an intake and exhaust system of an internal combustion engine, an electric motor that generates a driving force for driving the valve body, and voltage application to the electric motor are controlled. What is provided with a control part is known. Such a valve device is employed in, for example, a throttle device that increases or decreases the flow rate of intake air and an EGR device that increases or decreases the recirculation amount of exhaust gas to the intake side (see, for example, Patent Document 1). .

  In recent years, in vehicles equipped with a battery with a nominal voltage of 24V, a valve device that employs an electric motor with a rated voltage of 12V instead of the electric motor with a rated voltage of 24V is known in order to suppress heat generation and reduce the size of the electric motor. It has become. And a control part performs duty-ratio control regarding the voltage application from a battery to an electric motor in order to control suitably the voltage application from the battery of nominal voltage 24V to the electric motor of rated voltage 12V.

That is, the control unit controls the duty ratio indicating the ON / OFF period ratio of the voltage application from the battery to the electric motor as an upper limit of 50%, thereby applying the voltage from the battery having the nominal voltage of 24V to the electric motor having the rated voltage of 12V. It controls suitably.
Note that the electric motor having a rated voltage of 12V operates favorably by power supply from a battery having a nominal voltage of 12V.

  However, when duty ratio control is performed in the voltage application from the battery to the electric motor, a so-called ripple is generated in the current flowing through the electric motor (see FIG. 6). As a result, the heat generation suppression effect due to the adoption of the electric motor having the rated voltage of 12V instead of the electric motor having the rated voltage of 24V is partially reduced.

JP 2014-005814 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a valve by an electric motor incorporated in an intake / exhaust system of an internal combustion engine and having a rated voltage lower than a nominal voltage of a battery. In the valve device for driving the body, there is to suppress the ripple of the current flowing through the electric motor.

  A valve device according to the present invention includes a valve body that opens and closes a flow path that constitutes an intake and exhaust system of an internal combustion engine, an electric motor that generates a driving force for driving the valve body, and a control unit that controls voltage application to the electric motor. With. In addition, the electric motor is supplied with power from a battery having a nominal voltage higher than its rated voltage to generate driving force, and the control unit has a duty ratio that indicates the on / off period ratio of voltage application from the battery to the electric motor. Based on this, voltage application to the electric motor is controlled.

The control unit calculates a duty ratio based on the operating state of the internal combustion engine and outputs a signal for turning on / off based on the duty ratio. The period when the voltage application to the electric motor is turned on is shorter than the period when the control unit calculates the duty ratio.
Thus, the ON portion of the ON / OFF signal can be output more than once while the process for controlling the duty ratio is executed once. For this reason, since the frequency of an on-off signal can be raised, the ripple of the electric current which flows into an electric motor can be suppressed (refer FIG. 5).

It is explanatory drawing of a valve apparatus (Example). It is explanatory drawing of the drive circuit of an electric motor (Example). It is explanatory drawing of the relationship between a duty ratio calculation period and an on-off signal output period (Example). It is a flowchart showing the control method at the time of sticking generation | occurrence | production of a valve body (Example). It is explanatory drawing of an electric current ripple (Example). It is explanatory drawing of a current ripple (conventional example).

  Hereinafter, modes for carrying out the invention will be described based on examples. In addition, an Example discloses a specific example, and it cannot be overemphasized that this invention is not limited to an Example.

[Configuration of Example]
The configuration of the valve device 1 of the embodiment will be described with reference to FIG.
The valve device 1 opens and closes a flow path that constitutes an intake and exhaust system of an internal combustion engine (not shown). For example, the valve device 1 is used in an EGR device that recirculates exhaust gas to the intake side. (Hereinafter, it is used to open and close the EGR flow path 2).
And the valve apparatus 1 is provided with the valve body 3, the electric motor 5, and the control part 6 which are demonstrated below.

  The valve body 3 is a disk-shaped butterfly valve, for example, and opens and closes the EGR flow path 2 by rotating. A seal ring 8 that closes the periphery of the valve body 3 and the flow path wall 7 of the EGR flow path 2 when the EGR flow path 2 is closed is attached to the peripheral edge of the valve body 3.

  Here, the seal ring 8 is provided as, for example, a C-shaped ring to form a joint (not shown), and fits into a fitting groove 9 provided at the periphery of the valve body 3. And rotate together with the valve body 3. And when the EGR flow path 2 is closed, the seal ring 8 is slidably contacted with the flow path wall 7 in a ring shape and closes the periphery of the valve body 3 and the flow path wall 7. At this time, the seal ring 8 is in sliding contact with the flow path wall 7 in an elastically deformed state so as to narrow the joint.

The valve body 3 is rotatably accommodated in a cylindrical nozzle 11 press-fitted into the body 10 of the valve device 1. Here, the inner peripheral surface of the nozzle 11 forms a flow path wall 7 that receives the sliding contact of the seal ring 8.
Here, the valve body 3 and the nozzle 11 are made of, for example, stainless steel from the viewpoint of heat resistance and corrosion resistance.
Moreover, the body 10 is provided with, for example, an aluminum alloy from the viewpoint of weight reduction and heat dissipation.

Here, the valve body 3 is rotatably supported in the nozzle 11 via the shaft 13. That is, the valve body 3 is rotated integrally with the shaft 13 to adjust the opening degree of the EGR flow path 2.
The shaft 13 has a cylindrical shape and rotates around its axis.
The body 10 houses the electric motor 5.

The electric motor 5 generates a driving force for rotationally driving the valve body 3.
More specifically, the valve body 3 is rotated by decelerating the rotation of the electric motor 5 by the speed reducer 15 in which a plurality of gears are combined, and the rotational torque amplified by the deceleration is transmitted.
That is, the rotational torque amplified by the speed reducer 15 is transmitted to the shaft 13, and the valve body 3 is rotated by rotating the shaft 13.

The valve device 1 is provided with a return spring 19 that urges the valve body 3 in the valve closing direction.
The return spring 19 is a coil spring and is coaxially disposed around the shaft 13.
The return spring 19 is assembled between the body 10 and the speed reducer 15.

  The control unit 6 constitutes the center of control for the internal combustion engine, and signals are input from various sensors that are mounted on the vehicle and detect parameters indicating the operation state and control state of the internal combustion engine. The control unit 6 also stores an input circuit that processes the input signal, a CPU that performs control processing related to the control of the internal combustion engine 6 based on the input signal, data and programs necessary for control of the internal combustion engine, and the like. And an output circuit for outputting a signal necessary for controlling the internal combustion engine based on the processing result of the CPU.

Here, the valve device 1 is provided with a rotation angle sensor 25 that detects the rotation angle of the valve body 3 as one of various sensors that output signals to the control unit 6.
The rotation angle sensor 25 is housed in a resin sensor case 27.
The body 10 and the sensor case 27 are integrated by abutting and fastening the flange of the body 10 and the flange of the sensor case 27, whereby the rotation angle sensor 25 is fixed to one end side of the shaft 13.

  The control unit 6 controls voltage application from the battery 29 to the electric motor 5. More specifically, the voltage application to the electric motor 5 is controlled based on the duty ratio DR indicating the ON / OFF period ratio of the voltage application from the battery 29 to the electric motor 5.

Here, the control unit 6 executes the opening degree control process of the EGR flow path 2 once in the control cycle T set for the CPU, and calculates the duty ratio DR once in the process. Yes.
In this process, the control unit 6 first calculates the command value of the opening degree of the EGR flow path 2, that is, the rotation angle of the valve body 3 in accordance with the operating state of the internal combustion engine. Next, the duty ratio DR of voltage application from the battery 29 to the electric motor 5 is calculated so as to eliminate the difference between the detected value of the rotation angle of the valve body 3 by the rotation angle sensor 25 and the command value of the rotation angle. Thereby, the control unit 6 calculates the duty ratio DR based on the operating state of the internal combustion engine.
Then, the control unit 6 outputs a signal for turning on / off the voltage application to the electric motor 5 based on the calculated duty ratio DR.

[Features of Examples]
Next, a characteristic configuration of the embodiment will be described with reference to FIG.
Here, the rated voltage of the electric motor 5 is 12V. The nominal voltage of the battery 29 that supplies power to the electric motor 5 is 24V, which is higher than the rated voltage of the electric motor 5.

The control unit 6 outputs a signal for turning on / off the voltage application to the electric motor 5 to the voltage application unit 30 based on the calculated duty ratio DR. This signal is, for example, a rectangular 0V, 5V on / off signal (hereinafter, a 5V signal may be referred to as an on signal and a 0V signal may be referred to as an off signal).
The voltage application unit 30 applies the voltage of the battery 29 to the electric motor 5, and includes, for example, an H bridge circuit 30a and a control circuit 30b. Here, one end of the H-bridge circuit 30a is connected to the positive electrode of the battery 29, and the other end is grounded.

Then, the control circuit 30b controls the on / off of the four switching elements Tr1 to Tr4 of the H bridge circuit 30a according to the input of the on / off signal from the control unit 6, thereby applying a voltage from the battery 29 to the electric motor 5. Controls on / off.
Note that the switching elements Tr1 to Tr4 are, for example, MOSFETs that are turned on so that the source terminal and the drain terminal become conductive when a voltage is applied to the gate terminal.

  More specifically, the control circuit 30b continues to apply the voltage of the battery 29 to the electric motor 5 during the period when the 5V ON signal is given. That is, for example, the control circuit 30b turns on Tr1 and Tr4 and turns off Tr2 and Tr3 during the period. Thus, in the above period, 24V from the positive electrode of the battery 29 is applied to one terminal of the electric motor 5, the other terminal of the electric motor 5 is grounded, and voltage application to the electric motor 5 is on. It becomes.

And the voltage applied to the electric motor 5 is set to 0V during the period when the OFF signal of 0V is given. That is, for example, the control circuit 30b turns on Tr3 and Tr4 and turns off Tr1 and Tr2 during the period. Thereby, in the said period, both terminals of the electric motor 5 are earth | grounded, and the voltage application to the electric motor 5 will be in the OFF state.
As described above, voltages of 0V and 24V are alternately applied from the battery 29 to the electric motor 5 at the duty ratio DR of the on / off signal input to the control circuit 30b.

  Here, the cycle t when the voltage application to the electric motor 5 is turned on is shorter than the control cycle T in which the control unit 6 calculates the duty ratio DR, that is, the control cycle T of the opening control of the EGR flow path 2. (See FIG. 3). That is, the control unit 6 outputs the ON portion of the ON / OFF signal a plurality of times while executing the process of calculating the duty ratio DR once. FIG. 3 illustrates an example in which ON is output four times during the control period T.

Further, when controlling the voltage application to the electric motor 5, the control unit 6 performs the upper limit restriction control for restricting the duty ratio DR so as not to exceed the upper limit value UL. Here, the upper limit UL is a value that does not exceed 50%, which is the ratio of the rated voltage 12V of the electric motor 5 to the nominal voltage 24V of the battery 29, and is, for example, 40%.
Further, the control unit 6 determines whether or not the valve body 3 is fixed, and increases the upper limit value UL of the duty ratio DR to 50% when it is determined that the valve body 3 is fixed.

[Control method of embodiment]
A control method at the time of occurrence of sticking of the valve body 3 of the embodiment will be described with reference to the flowchart of FIG.
First, in step S100, the control unit 6 determines whether or not the calculated duty ratio DR is the upper limit value UL.
When it is determined that the duty ratio DR is the upper limit value UL (YES), the process proceeds to step S110. When it is determined that the duty ratio DR is not the upper limit value UL, the determination in step S100 is repeated.

Next, in step S110, the control unit 6 determines whether or not the valve body 3 is stuck depending on whether or not the period TS that is the upper limit value UL exceeds 200 ms.
When it is determined that the period TS that is the upper limit value UL exceeds 200 ms (YES), it is determined that the valve body 3 is stuck, and the process proceeds to S120.
In S120, the upper limit value UL of the duty ratio DR is set to 50%, and the process ends.

When it is determined that the period TS that is the upper limit value UL does not exceed 200 ms (NO), it is determined that the valve body 3 is not stuck, and the process proceeds to S130.
In S130, the upper limit UL of the duty ratio DR is set to 40%, and the process is terminated.
Note that the release of the sticking of the valve body 3 after the upper limit UL of the duty ratio DR is set to 50% is executed in a separate control flow.

[Effects of Examples]
According to the valve device 1 of the embodiment, the cycle t when the voltage application to the electric motor 5 is turned on is the control cycle T in which the control unit 6 calculates the duty ratio DR, that is, the opening control of the EGR flow path 2. It is shorter than the control period T.
Thereby, while the process which controls the opening degree of the EGR flow path 2 is executed once, the ON portion of the ON / OFF signal can be output more than once. For this reason, since the frequency of an on-off signal can be raised, the ripple of the electric current which flows into the electric motor 5 can be suppressed (refer FIG. 5).

  Further, according to the valve device 1 of the embodiment, when the control unit 6 controls the voltage application to the electric motor 5, the upper limit regulation control that regulates the duty ratio DR so as not to exceed the upper limit value UL. It is carried out. Here, the upper limit UL is a value that does not exceed 50%, which is the ratio of the rated voltage 12 V of the electric motor 5 to the nominal voltage 24 V of the battery 29.

  Thereby, the overcurrent supply to the electric motor 5 resulting from the nominal voltage 24V of the battery 29 being higher than the rated voltage 12V of the electric motor 5 can be suppressed, and heat generation and consumption of the electric motor 5 can be suppressed.

Further, according to the valve device 1 of the embodiment, the control unit 6 determines whether or not the valve body 3 is fixed, and when it is determined that the valve body 3 is fixed, the upper limit value of the duty ratio DR is 50. Increase to%.
Thereby, the torque of the electric motor 5 can be increased and the sticking of the valve body 3 can be easily released.

[Modification]
Various modifications can be considered for the present invention without departing from the gist thereof.
For example, the valve device 1 of the embodiment has been used in an EGR device, but the valve device 1 may be used in a throttle device that increases or decreases the flow rate of intake air of an internal combustion engine.

In the embodiment, when it is determined that the valve body 3 is fixed, the upper limit value of the duty ratio DR is increased to 50%. However, the upper limit value UL of the duty ratio DR is set to a rated voltage of 12 V with respect to the nominal voltage of 24 V. It is good also as a value exceeding 50% which is a ratio, for example, 60%.
Thereby, the torque of the electric motor 5 can be further increased, and the sticking of the valve body 3 can be easily released.

Further, in the embodiment, the sticking of the valve body 3 is determined based on the period during which the duty ratio DR is the upper limit value UL. The sticking of the body 3 may be determined.
In the embodiment, the nominal voltage of the battery 29 is 24 V, but is not limited to this value. Similarly, in the embodiment, the rated voltage of the electric motor 5 is 12 V, but is not limited to this value.

DESCRIPTION OF SYMBOLS 1 Valve apparatus 2 EGR flow path (flow path) 3 Valve body 5 Electric motor 6 Control part 29 Battery

Claims (3)

A valve body (3) that opens and closes a flow path (2) constituting an intake / exhaust system of an internal combustion engine, an electric motor (5) that generates a driving force for driving the valve body, and voltage application to the electric motor A control unit (6) for controlling,
The electric motor is powered by a battery (29) having a nominal voltage higher than its rated voltage to generate the driving force,
In the valve device (1) for controlling the voltage application to the electric motor based on a duty ratio indicating a period ratio of ON / OFF of voltage application from the battery to the electric motor,
The control unit calculates the duty ratio based on the operating state of the internal combustion engine, and outputs a signal for turning on and off the voltage application to the electric motor based on the duty ratio,
The valve device according to claim 1, wherein a cycle in which voltage application to the electric motor is turned on is shorter than a cycle in which the control unit calculates the duty ratio. The valve device according to claim 1,
The control unit, when controlling the voltage application to the electric motor, is performing an upper limit restriction control for restricting the duty ratio so as not to exceed an upper limit value,
The upper limit value is a value that does not exceed a ratio of the rated voltage to the nominal voltage. The valve device according to claim 2,
The said control part determines the presence or absence of the adhering of the said valve body, and when it determines with the said valve body adhering, the said upper limit is raised, The valve apparatus characterized by the above-mentioned.

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