WO2022138353A1 - Hunting detection device, and hunting detection method - Google Patents

Abstract

A hunting detection device of the present disclosure is for detecting hunting in an engine equipped with a carburetor. The hunting detection device comprises: an acquisition unit that is configured to acquire the engine speed and the outside air temperature which is measured by a temperature sensor; a detection unit that is configured to detect hunting if a speed fluctuation state in which the outside air temperature is equal to or below a first reference value is detected; and an opening degree controller that is configured to control the opening degree of a choke valve provided to an intake passage of the engine. If the detection unit detects hunting, the opening degree controller executes closing control to reduce the opening degree of the choke valve.

Description

Hunting detection device and hunting detection method

The present disclosure relates to a hunting detection device and a hunting detection method for detecting hunting of an engine provided with a vaporizer.
This application claims priority based on Japanese Patent Application No. 2020-210965 filed with the Japan Patent Office on December 21, 2020, the contents of which are incorporated herein by reference.

An auto choke device configured to adjust the air-fuel ratio by controlling the opening of the choke valve when the engine is started has been proposed. For example, Patent Document 1 discloses an auto choke device that determines an opening degree of a choke valve by using temperature information representing an engine temperature at the time of starting an engine. As the engine temperature, the lubricating oil temperature, the cylinder head temperature, the cooling water temperature and the like are used.

Japanese Unexamined Patent Publication No. 2005-256757

By the way, in the type of engine equipped with a carburetor, fuel is supplied from the carburetor. In this case, in a low temperature environment, the density of the intake air may increase, resulting in a relative shortage of fuel. As a result, combustion becomes unstable, misfires are repeated, the engine speed becomes unstable, and the governor cannot properly control the throttle, resulting in hunting.

The engine is provided with an electronic rotation speed control device or a mechanical rotation speed control device. The mechanical rotation speed control device extracts the rotation speed of the engine by centrifugal force, automatically closes the throttle when the rotation speed is high, and automatically opens the throttle when the rotation speed is low to keep the rotation speed constant. Includes a governor configured to keep in. Hunting is particularly likely to occur in such a mechanical rotation speed control device.

It is known that hunting is suppressed by lowering the air-fuel ratio (that is, the number of revolutions becomes easier to stabilize), and that it converges if warm-up operation is continued. However, since hunting may be mistaken for a failure, if hunting cannot be suppressed in a short time, the commercial value will decrease. Patent Document 1 does not disclose a configuration for detecting hunting or a configuration for suppressing hunting in a short time.

In view of the above circumstances, it is an object of the present disclosure to provide a hunting detection device and a hunting detection method capable of detecting hunting of an engine equipped with a vaporizer.

The hunting detection device according to the present disclosure is
A hunting detection device for detecting hunting of an engine equipped with a vaporizer.
An acquisition unit configured to acquire the outside air temperature measured by the temperature sensor and the engine speed, and an acquisition unit.
A detection unit configured to detect the hunting when the fluctuation state of the rotation speed is detected when the outside air temperature is equal to or lower than the first reference value.
It is provided with an opening degree control unit configured to control the opening degree of a choke valve provided in the intake passage of the engine.
When the detection unit detects the hunting, the opening degree control unit executes closing control for reducing the opening degree of the choke valve.

The hunting detection method according to the present disclosure is
It is a hunting detection method for detecting hunting of an engine equipped with a vaporizer.
The step of acquiring the outside air temperature measured by the temperature sensor and the rotation speed of the engine, and
A step of detecting the hunting when the fluctuation state of the rotation speed is detected when the outside air temperature is equal to or lower than the first reference value, and
A step of controlling the opening degree of a choke valve provided in the intake passage of the engine and executing closing control for reducing the opening degree of the choke valve when the hunting is detected in the detection step. When,
including.

According to the present disclosure, it is possible to provide a hunting detection device and a hunting detection method capable of detecting hunting of an engine equipped with a vaporizer.

It is a schematic diagram which illustrates the whole structure of the engine which includes the hunting detection device which concerns on one Embodiment. It is a block diagram which shows schematic structure of the hunting detection apparatus which concerns on one Embodiment. It is a conceptual diagram which shows an example of the temporal change of the rotation speed when the hunting detection apparatus which concerns on one Embodiment does not detect hunting. It is a conceptual diagram which shows an example of the temporal change of the rotation speed when the hunting detection apparatus which concerns on one Embodiment detects hunting. It is a flowchart which shows an example of the process executed by the hunting detection apparatus which concerns on one Embodiment.

Hereinafter, some embodiments will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the invention, but are merely explanatory examples. ..
For example, expressions that represent relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" are exact. Not only does it represent such an arrangement, but it also represents a tolerance or a state of relative displacement at an angle or distance to the extent that the same function can be obtained.
For example, expressions such as "same", "equal", and "homogeneous" that indicate that things are in the same state not only represent exactly the same state, but also have tolerances or differences to the extent that the same function can be obtained. It shall also represent the existing state.
For example, an expression representing a shape such as a square shape or a cylindrical shape not only represents a shape such as a square shape or a cylindrical shape in a geometrically strict sense, but also an uneven portion or a chamfering within a range where the same effect can be obtained. It shall also represent the shape including the part and the like.
On the other hand, the expressions "to have", "to have", "to have", "to include", or "to have" one component are not exclusive expressions that exclude the existence of other components.

(Overall engine configuration)
FIG. 1 is a schematic diagram illustrating an overall configuration of an engine 1 including a hunting detection device 100 according to an embodiment. The engine 1 may be an engine of a work machine such as a small farm tool, a mower, a rice transplanter, or a cultivator, or may be an engine of a vehicle.

As shown in FIG. 1, the cylinder head of the engine 1 is provided with a spark plug 3 for igniting the engine 1, and an intake valve 4 and an exhaust valve 5 for adjusting the intake amount and the exhaust amount. The engine 1 includes a rotation speed detection sensor 20 configured to detect the rotation speed of the engine 1 and a temperature sensor 10 for measuring the outside air temperature. In some embodiments, the engine 1 further comprises a temperature sensor 2 for measuring the temperature of the ignition coil 13, as shown, for example, FIG.

In some embodiments, the rotation speed detection sensor 20 detects the rotation speed based on the primary line signal of the ignition coil 13. The primary line signal of the ignition coil 13 is not a signal due to energization, but a pulse signal based on sparks generated for each rotation. The rotation speed detection sensor 20 may be configured to detect the rotation speed based on the signal obtained from the inverter instead of the primary line signal of the ignition coil 13. Since the purpose of the rotation speed detection sensor 200 is to improve the accuracy of hunting detection, it is possible not to provide the sensor 200 in consideration of cost.

Further, in some embodiments, the engine 1 has a rotation speed control device 30 configured to open and close the throttle (throttle valve 8) according to the rotation speed of the engine 1, for example, as shown in FIG. Further prepare. The rotation speed control device 30 may be a mechanical rotation speed control device that utilizes centrifugal force according to the rotation speed of the engine 1, or may be an electronic rotation speed control device including an inverter and a motor. good. The rotation speed control device 30 includes a governor configured to maintain a constant rotation speed by automatically closing the throttle when the rotation speed is high and automatically opening the throttle when the rotation speed is low.

A vaporizer (carburetor) 7 is connected to the intake pipe 6 provided with the intake valve 4. The vaporizer 7 includes a throttle valve 8 arranged on the downstream side and a choke valve 9 arranged on the upstream side thereof. Air and fuel (not shown) are supplied to the vaporizer 7. The choke valve 9 provided in the intake passage of the engine 1 is opened and closed by a stepping motor 11.

As shown in FIG. 1, the engine 1 may be connected to a generator 12 configured to generate an alternating current by being driven by the engine 1. A recoil starter (not shown) for manual starting may be connected to the crank shaft of the engine 1.

The hunting detection device 100 is a device for detecting hunting of the engine 1. The hunting detection device 100 may be an auto-choke device or a device capable of communicating with the auto-choke device. In some embodiments, the hunting detection device 100 drives the stepping motor 11 to control the opening degree of the choke valve 9 so that an appropriate air-fuel ratio can be obtained.

(Configuration of hunting detection device)
Hereinafter, the configuration of the hunting detection device 100 will be described. The hunting detection device 100 includes, for example, a central processing unit (CPU) including a processor, a random access memory (RAM), a read-only memory (ROM), an I / O interface, and the like, and is configured as a microcomputer.

FIG. 2 is a block diagram schematically showing the configuration of the hunting detection device 100 according to the embodiment. As shown in FIG. 2, the hunting detection device 100 includes an acquisition unit 110 configured to acquire the outside air temperature and the rotation speed of the engine 1, a detection unit 120 configured to detect hunting, and a choke. It includes an opening degree control unit 130 configured to control the opening degree of the valve 9.

The acquisition unit 110 acquires the outside air temperature measured by the temperature sensor 10 from the temperature sensor 10. Further, the acquisition unit 110 acquires the rotation speed of the engine 1 measured by the rotation speed detection sensor 20 from the rotation speed detection sensor 20.

The detection unit 120 detects hunting of the engine 1 when the outside air temperature acquired by the acquisition unit 110 is equal to or lower than the first reference value and a fluctuation state is detected at the rotation speed of the engine 1 acquired by the acquisition unit 110. The first reference value is set to a temperature reference value at which a low temperature environment can be estimated, and is set to, for example, a temperature within the range of −5 ° C. or higher and 10 ° C. or lower.

The opening degree control unit 130 controls the opening degree of the choke valve 9 by controlling the number of input pulses to the stepping motor 11, for example. In some embodiments, the opening degree control unit 130 executes closing control for reducing the opening degree of the choke valve 9 when the detection unit 120 detects hunting. In some embodiments, the opening control unit 130 releases the closing control and chokes when a predetermined time has elapsed from the execution of the closing control or when the temperature of the ignition coil 13 reaches the second reference value. Increase the opening of the valve 9. The second reference value is set to, for example, a temperature within the range of 30 ° C. or higher and 35 ° C. or lower.

Note that the control at the time of hunting detection is not limited to the opening control of the choke valve 9. For example, the control at the time of hunting detection may be the control of the fuel supply amount. That is, the hunting detection device 100 may be configured to control a device other than the choke valve 9 to adjust the air-fuel ratio and suppress hunting.

FIG. 3A is a conceptual diagram showing an example of a temporal change in the rotation speed when the hunting detection device 100 according to the embodiment does not detect hunting. FIG. 3B is a conceptual diagram showing an example of a temporal change in the rotation speed when the hunting detection device 100 according to the embodiment detects hunting. Comparing FIGS. 3A and 3B, it can be seen that the variation in the rotation speed is large in FIG. 3A, whereas the variation in the rotation speed is small in FIG. 3B. However, in order to detect the fluctuation state of the rotation speed, a discrimination standard is necessary.

Therefore, for example, the detection unit 120 may be configured to detect the fluctuation state on the condition that the fluctuation of a predetermined amount or more occurs a predetermined number of times or more in the change of the rotation speed in the first time. As a result, the fluctuation state of the engine speed can be detected only when the hunting and presumable conditions are satisfied.

In the above configuration, the first time is preferably set to a time within the range of 1 second or more and 5 seconds or less. The predetermined amount is preferably set to a rotation speed within the range of 100 rpm or more and 300 rpm or less. The predetermined number of times is preferably set to a number within the range of 2 times or more and 5 times or less. In this case, since the conditions for hunting and the presumable rotation speed fluctuation are set, the accuracy of detecting the fluctuation state of the rotation speed of the engine 1 can be improved.

(Process flow)
Hereinafter, the flow of processing executed by the hunting detection device 100 will be described. FIG. 4 is a flowchart showing an example of a process executed by the hunting detection device 100 according to the embodiment. This process is performed while the engine 1 including the vaporizer 7 is in operation.

As shown in FIG. 4, the acquisition unit 110 of the hunting detection device 100 acquires the measured values of the outside air temperature and the rotation speed (step S1). Specifically, the acquisition unit 110 of the hunting detection device 100 acquires the outside air temperature measured by the temperature sensor 10 and the rotation speed of the engine 1 measured by the rotation speed detection sensor 20. The acquisition unit 110 may collectively acquire the time-series data of each measured value, or may acquire the latest measured value each time the measured value is obtained.

The detection unit 120 of the hunting detection device 100 performs a process for detecting the fluctuation state of the rotation speed based on the measured value of the rotation speed of the engine 1, and determines whether or not the fluctuation state is detected (step S2). .. For example, the detection unit 120 of the hunting detection device 100 makes this determination based on whether or not a predetermined amount or more of the change in the rotation speed in the first time has occurred more than a predetermined number of times.

When it is determined that the fluctuation state has not been detected (step S2; No), the hunting detection device 100 skips the subsequent processes of steps S3 to S5. On the other hand, when it is determined that the fluctuation state has been detected (step S2; Yes), the detection unit 120 of the hunting detection device 100 determines whether or not the outside air temperature acquired by the acquisition unit 110 is equal to or less than the first reference value. (Step S3).

When it is determined that the outside air temperature is not equal to or lower than the first reference value (step S3; No), the hunting detection device 100 skips the subsequent processes of steps S4 and S5. On the other hand, when it is determined that the outside air temperature is equal to or lower than the first reference value (step S3; Yes), the detection unit 120 of the hunting detection device 100 detects that the hunting state is in the hunting state. Further, the opening degree control unit 130 of the hunting detection device 100 executes closing control for reducing the opening degree of the choke valve 9 (step S4).

The opening control unit 130 determines whether or not the end condition is satisfied, with the end condition being whether a predetermined time has elapsed since the closing control was executed or the temperature of the ignition coil 13 has reached the second reference value. (Step S5). If the end condition is not satisfied (step S5; No), the opening degree control unit 130 returns to step S4 and continues the closing control. On the other hand, when the end condition is satisfied (step S5; Yes), the opening degree control unit 130 releases the closing control and increases the opening degree of the choke valve 9.

The processing described above may be performed periodically during the operation of the engine 1. The hunting detection device 100 is not limited to the configuration that controls the opening degree. The hunting detection device 100 may be configured to detect the presence or absence of hunting and transmit the detection result to another device.

The present disclosure is not limited to the above-mentioned embodiment, and includes a form in which the above-mentioned embodiment is modified and a form in which a plurality of embodiments are appropriately combined.

(summary)
The contents described in each of the above embodiments are grasped as follows, for example.

(1) The hunting detection device (100) according to the present disclosure is
A hunting detection device (100) for detecting hunting of an engine (1) provided with a vaporizer (7).
An acquisition unit (110) configured to acquire the outside air temperature measured by the temperature sensor (10) and the engine speed.
A detection unit (120) configured to detect the hunting when the fluctuation state of the rotation speed is detected when the outside air temperature is equal to or lower than the first reference value.
An opening control unit (130) configured to control the opening degree of the choke valve (9) provided in the intake passage of the engine (1) is provided.
When the detection unit (120) detects the hunting, the opening degree control unit (130) executes closing control for reducing the opening degree of the choke valve (9).

According to the above configuration, hunting is detected when the outside air temperature is equal to or lower than the first reference value (that is, in a low temperature environment) and the rotation speed is in a predetermined fluctuation state. Therefore, it is possible to detect the hunting of the engine (1) provided with the vaporizer (7). It is also possible to use the hunting detection result for control for suppressing hunting in a short time (for example, control for adjusting the air-fuel ratio). Further, when hunting is detected, the opening degree of the choke valve (9) is reduced to lower the air-fuel ratio, so that hunting can be suppressed. Further, by warming up the engine (1) in this state, the hunting can be converged in a short time.

(2) In some embodiments, in the configuration described in (1) above,
Further equipped with a temperature sensor (2) for measuring the temperature of the ignition coil (13),
The opening control unit (130) releases the closing control and the choke valve when a predetermined time has elapsed from the execution of the closing control or when the temperature of the ignition coil reaches the second reference value. Increase the opening of (9).

When a predetermined time has elapsed from the execution of the closing control or when the temperature of the ignition coil (13) reaches the second reference value, it is conceivable that the hunting converges due to the rise in the engine temperature. According to the above configuration, since the closing control is released in such a case, it is possible to reduce the possibility that the execution time of the closing control becomes excessively long.

(3) In some embodiments, in the configuration described in (1) or (2) above,
The first reference value is set to a temperature within the range of −5 ° C. or higher and 10 ° C. or lower.

According to the above configuration, it is possible to discriminate the low temperature environment where hunting is likely to occur by the first reference value.

(4) In some embodiments, in the configuration according to any one of (1) to (3) above,
The second reference value is set to a temperature within the range of 30 ° C. or higher and 35 ° C. or lower.

According to the above configuration, it is possible to release the closing control at an appropriate timing.

(5) In some embodiments, in the configuration according to any one of (1) to (4) above,
The detection unit (120) detects the fluctuation state on condition that the fluctuation of a predetermined amount or more occurs a predetermined number of times or more in the change of the rotation speed in the first time.

According to the above configuration, since the fluctuation state of the rotation speed of the engine (1) is detected only when the condition that can be estimated as hunting is satisfied, over-detection can be suppressed.

(6) In some embodiments, in the configuration described in (5) above,
The first time is set to a time within the range of 1 second or more and 5 seconds or less.
The predetermined amount is set to a rotation speed within the range of 100 rpm or more and 300 rpm or less.
The predetermined number of times is set to a number within the range of 2 times or more and 5 times or less.

According to the above configuration, since the conditions for hunting and the presumable rotation speed fluctuation are set, it is possible to improve the detection accuracy of the rotation speed fluctuation state of the engine (1).

(7) In some embodiments, in the configuration according to any one of (1) to (6) above,
The detection unit (120) determines the fluctuation state based on the rotation speed detected by the rotation speed detection sensor (20) based on the primary line signal of the ignition coil (13) for igniting the engine (1). To detect.

According to the above configuration, the primary line signal of the ignition coil (13), which is widely used in the engine (1), is used. In this case, it is advantageous in that it is not necessary to separately add a dedicated sensor for detecting the rotation speed of the engine (1).

(8) In some embodiments, in the configuration according to any one of (1) to (7) above,
The engine (1) includes a mechanical rotation speed control device (30) configured to open and close the throttle according to the rotation speed.

According to the above configuration, it is meaningful because it is applied to the engine (1) provided with the mechanical rotation speed control device (30) in which hunting is likely to occur.

(9) The hunting detection method according to the present disclosure is
It is a hunting detection method for detecting hunting of an engine (1) equipped with a vaporizer (7).
A step of acquiring the outside air temperature measured by the temperature sensor (10) and the rotation speed of the engine (1), and
A step of detecting the hunting when the fluctuation state of the rotation speed is detected when the outside air temperature is equal to or lower than the first reference value, and
When the opening degree of the choke valve (9) provided in the intake passage of the engine (1) is controlled and the hunting is detected in the detection step, the opening degree of the choke valve (9) is reduced. And the steps to perform the closure control to
including.

According to the above method, hunting is detected when the outside air temperature is equal to or lower than the first reference value (that is, in a low temperature environment) and the rotation speed is in a predetermined fluctuation state. Therefore, it is possible to detect the hunting of the engine (1) provided with the vaporizer (7). It is also possible to use the hunting detection result for control to suppress hunting in a short time. Further, when hunting is detected, the opening degree of the choke valve (9) is reduced to lower the air-fuel ratio, so that hunting can be suppressed. Further, by warming up the engine (1) in this state, the hunting can be converged in a short time.

1 Engine 2, 10 Temperature sensor 3 Spark plug 4 Intake valve 5 Exhaust valve 6 Intake pipe 7 Vaporizer 8 Throttle valve 9 Chalk valve 11 Stepping motor 12 Generator 13 Ignition coil 20 Rotation speed detection sensor 30 Rotation speed control device 100 Hunting detection Device 110 Acquisition unit 120 Detection unit 130 Opening control unit

Claims (9)

A hunting detection device for detecting hunting of an engine equipped with a vaporizer.
An acquisition unit configured to acquire the outside air temperature measured by the temperature sensor and the engine speed, and an acquisition unit.
A detection unit configured to detect the hunting when the fluctuation state of the rotation speed is detected when the outside air temperature is equal to or lower than the first reference value.
An opening control unit configured to control the opening of a choke valve provided in the intake passage of the engine is provided.
The opening degree control unit is a hunting detection device that executes closing control for reducing the opening degree of the choke valve when the detection unit detects the hunting. Further equipped with a temperature sensor that measures the temperature of the ignition coil,
The opening control unit releases the closing control and opens the choke valve when a predetermined time has elapsed from the execution of the closing control or when the temperature of the ignition coil reaches the second reference value. The hunting detection device according to claim 1. The hunting detection device according to claim 1 or 2, wherein the first reference value is set to a temperature within the range of −5 ° C. or higher and 10 ° C. or lower. The hunting detection device according to any one of claims 1 to 3, wherein the second reference value is set to a temperature within the range of 30 ° C. or higher and 35 ° C. or lower. The hunting unit according to any one of claims 1 to 4, wherein the detection unit detects the fluctuation state on condition that the fluctuation of a predetermined amount or more occurs a predetermined number of times or more in the change of the rotation speed in the first time. Detection device. The first time is set to a time within the range of 1 second or more and 5 seconds or less.
The predetermined amount is set to a rotation speed within the range of 100 rpm or more and 300 rpm or less.
The hunting detection device according to claim 5, wherein the predetermined number of times is set to a number of times within the range of 2 times or more and 5 times or less. One of claims 1 to 6, wherein the detection unit detects the fluctuation state based on the rotation speed detected by the rotation speed detection sensor based on the primary line signal of the ignition coil for igniting the engine. Hunting detection device described in. The hunting detection device according to any one of claims 1 to 7, wherein the engine includes a mechanical rotation speed control device configured to open and close the throttle according to the rotation speed. It is a hunting detection method for detecting hunting of an engine equipped with a vaporizer.
The step of acquiring the outside air temperature measured by the temperature sensor and the rotation speed of the engine, and
A step of detecting the hunting when the fluctuation state of the rotation speed is detected when the outside air temperature is equal to or lower than the first reference value, and
A step of controlling the opening degree of a choke valve provided in the intake passage of the engine and executing closing control for reducing the opening degree of the choke valve when the hunting is detected in the detection step. When,
Hunting detection method including.

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