JP4659803B2 - Engine electronic governor - Google Patents

Description

  The present invention relates to an electronic governor for an engine.

  Recently, electronic governors that use an actuator to control the engine speed to a target speed are often used. When the engine is a diesel engine, the actuator adjusts the fuel supply amount so that the engine rotation speed approaches the target rotation speed by operating a metering rack that adjusts the fuel supply amount. As shown by the solid line in FIG. 3, this actuator has a hysteresis characteristic with respect to the actuator drive current. FIG. 3 is a diagram illustrating the hysteresis characteristics of the actuator. The vertical axis indicates the position of the metering rack that moves in accordance with the driving of the actuator, and the horizontal axis indicates the actuator driving current that drives the actuator. Due to this hysteresis characteristic, the actuator may not drive in response to changes in the actuator drive current. For example, if the actuator is driven so that the position of the metering rack is moved from point A to point B, the actuator will not be driven even if the actuator drive current is increased from point C to point D. Need to be increased. The width of the actuator drive current from point C to point D where the actuator is not driven is called the hysteresis width, and the actuator is not driven when the change width of the actuator drive current is shorter than the hysteresis width. In order to prevent the influence of this hysteresis characteristic, in the conventional electronic governor, the actuator is minutely vibrated by superimposing a dither current on the actuator drive current, and the response of the actuator is improved (see Patent Document 1). In order to minutely vibrate the actuator, the dither current amplitude (hereinafter referred to as dither width) is initially set to at least about half the hysteresis width of the actuator.

JP 2001-20789 A

  Thus, the dither width is initially set corresponding to the hysteresis width of the actuator, but the hysteresis width of the actuator varies depending on the engine temperature and the like.

  The actuator has a plunger and moves the metering rack in the axial direction by moving the plunger in the axial direction. The sliding resistance of the metering rack varies with the viscosity of the engine oil that varies with the engine temperature, and the hysteresis width of the actuator also varies with the engine temperature. That is, when the engine temperature decreases and the viscosity of the engine oil increases, the hysteresis width of the actuator increases. When the engine temperature increases and the viscosity of the engine oil decreases, the hysteresis width of the actuator decreases.

  FIG. 4 is a diagram showing that the hysteresis width of the actuator is increased by changing the engine temperature. As shown in FIG. 4, the hysteresis width (for example, the width from the broken line F point to the G point) after the engine temperature is lowered is the initial hysteresis width (for example, the width from the solid line H point to the I point). ) Bigger. For this reason, during cold weather, the hysteresis width increases due to a decrease in engine temperature, and the initial dither width corresponding to the initial hysteresis width becomes smaller than half of the hysteresis width of the actuator. As a result, the actuator and the metering rack do not vibrate slightly, and there is a risk that the response of the actuator will be reduced by the hysteresis characteristic. On the other hand, if the dither width is kept large even when the engine temperature rises, the dither width becomes a disturbance of control and the control stability is lowered during the warm period.

  An object of the present invention is to provide an engine electronic governor that solves the above-described problems, that is, an engine electronic governor that can enhance the response of an actuator and maintain high control stability.

The present invention controls the actuator drive current for driving the actuator (2) to cause the actuator (2) to operate the fuel metering means so that the fuel metering means causes the engine speed to approach the target speed. Adjust the supply amount,
A rotation speed detection means (3) for detecting the rotation speed of the engine, a target rotation speed setting means (4) for setting the target rotation speed, and the actuator drive current are controlled so that the rotation speed of the engine approaches the target rotation speed. Drive current control means (5), dither current superimposing means (6) for superimposing the dither current on the actuator drive current, and drive means (7) for outputting the actuator drive current with the dither current superimposed on the actuator (2) In the electronic governor of the equipped engine,
Disturbance determining means (8) for determining that the dither is a control disturbance is provided, and the disturbance determining means (8) is linked to the rotation speed detecting means (3) and the dither current superimposing means (6),
The disturbance determination means (8) calculates the time difference Δt and the rotation speed difference ΔR between adjacent peaks of the engine speed fluctuation, the time difference Δt is less than the predetermined time difference t, and the rotation speed difference ΔR is the predetermined rotation speed difference R. When the above number of times continues for a predetermined number n or more, the disturbance determination means (8) determines that the dither is a control disturbance, and based on this determination, the dither current superimposing means (6) An electronic governor for an engine, wherein the dither width of the dither current is reduced.

<Effect> The response of the actuator can be kept high.
Since the dither width can be increased until just before the dither becomes a disturbance of control, minute vibrations of the actuator and fuel metering means (such as a metering rack) are appropriately performed, and the response of the actuator can be kept high. it can.

<Effect> When it is determined that the dither is capable of maintaining control stability, the dither width of the dither current is reduced, so that the control stability can be maintained high.

<Effect> It is possible to efficiently suppress the engine rotation fluctuation based on the dither disturbance.
The disturbance determination means (8) calculates a time difference Δt and an engine speed difference ΔR between adjacent peaks of the engine speed fluctuation, the time difference Δt is less than the predetermined time difference t, and the engine speed difference ΔR is a predetermined engine speed difference R. When the above number of times continues for a predetermined number n or more, the disturbance determination means (8) determines that the dither is a control disturbance, so the engine rotation fluctuation is based on fluctuations in the external load or the like. Therefore, it is possible to clearly discriminate whether it is based on the disturbance of the dither, and it is possible to efficiently suppress the engine rotation fluctuation based on the disturbance of the dither.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an example of an electronic governor 1 for a diesel engine according to an embodiment of the present invention. This engine is used as a generator.
The electronic governor 1 according to the embodiment of the present invention controls the actuator driving current that drives the actuator 2. When the controlled actuator driving current is output to the actuator 2, the actuator 2 operates a fuel supply adjusting means (not shown) for adjusting the fuel supply amount, so that the engine speed approaches the target speed. Adjust the fuel supply amount. The actuator 2 is a solenoid, and the actuator drive current is an excitation current. The fuel supply adjusting means is, for example, a fuel metering rack provided in the fuel injection pump, and adjusts the fuel supply amount to the engine.
In the electronic governor 1 of the present embodiment, the rotation speed detection means 3, the target rotation speed setting means 4, the drive current control means 5, the dither current superimposing means 6, the drive means 7, and the dither become control disturbances. Disturbance determining means 8 for determining whether or not the

The rotational speed detection means 3 detects the rotational speed of the engine. The rotation speed detection means 3 detects the rotation speed based on, for example, the actuator drive current or the number of pulses detected per rotation speed.
The target rotational speed setting means 4 sets the target rotational speed. The target rotation speed setting means 4 is, for example, a speed control lever.

The drive current control means 5 controls the actuator drive current so that the engine speed approaches the target speed. The drive current control means 5 includes a rotation speed deviation calculation means 51, a target current value calculation means 52, a current detection means 53, a current deviation calculation means 54, and a PWM signal calculation means 55. These means of the drive current control means 5 are realized by a computer such as an ECU, for example.
The rotational speed deviation calculating means 51 calculates the rotational speed deviation between the engine rotational speed and the target rotational speed. The target current value calculation means 52 sets the actuator drive current value so that the calculated rotation speed deviation is within an allowable range. The current detection means 53 performs A / D conversion on the current detected from the actuator by a shunt resistor (not shown), and calculates the detected current value of the actuator from the value after the A / D conversion. The current deviation calculation means 54 calculates a current value deviation between the set actuator drive current value and the detected current value of the actuator. The PWM signal calculation means 55 calculates the duty ratio of the PWM signal that makes the calculated current value deviation within an allowable range based on PID control.

The disturbance determining means (8) is linked to the rotation speed detecting means (3) and the dither current superimposing means (6).
As shown in FIGS. 2A and 2B, the disturbance discriminating means (8) calculates a time difference Δt and an engine speed difference ΔR between adjacent peaks of the engine speed fluctuation, and the time difference Δt is a predetermined time difference t. If the number of times that the rotational speed difference ΔR is greater than or equal to the predetermined rotational speed difference R continues for a predetermined number n or more, the disturbance determination means (8) determines that the dither is a control disturbance. Based on this determination, the dither current superimposing means (6) reduces the dither width of the dither current. The time difference t is 100 ms (milliseconds), the rotational speed difference R is 10 rpm, and the number of times n is 10 times. In general, the time difference due to load fluctuation is 600 to 1000 ms and the rotation speed difference is about 100 rpm, so that the rotation fluctuation due to load fluctuation and the rotation fluctuation due to dither can be clearly distinguished.
FIG. 2B shows the engine speeds R0 to R7, the time differences Δt0 to Δt7, the rotational speeds at the generation times to to t7 of the continuous fluctuations in the engine speed when the dither is a control disturbance. Differences ΔR1 to R7 are shown.

  As shown in FIG. 1, the dither current superimposing means 6 changes the dither width of the dither current based on the determination by the disturbance determination means (8), and then superimposes the dither current on the actuator drive current. The dither current superimposing unit 6 includes a dither width setting unit 61 and a PWM signal output unit 62. These means of the dither current superimposing means 6 are realized by a computer such as an ECU, for example.

  As shown in FIG. 1, the dither width setting means 61 changes the dither width of the dither current based on the determination by the disturbance determination means (8). That is, the dither width setting means 61 reduces the dither width of the dither current by reducing the pulse width of the dither signal based on the fact that the disturbance determination means (8) has determined that the dither is a control disturbance. To do.

  The PWM signal output means 62 superimposes a dither signal having a pulse width controlled to increase the dither width of the dither current on the PWM signal calculated by the PWM signal calculation means 55. Next, the PWM signal output means 62 outputs a PWM signal on which the dither signal is superimposed to the driving means 7.

  Based on the PWM signal input from the PWM signal output means 62, the drive means 7 outputs an actuator drive current on which the dither current is superimposed to the actuator 2. For example, when the actuator 2 is a solenoid, the driving unit 7 includes an excitation circuit.

  The electronic governor described above is only one embodiment of the present invention, and the present invention is not limited to this embodiment, and can be appropriately changed within the technical scope based on the claims. Can be implemented.

It is the block diagram which showed an example of the electronic governor which concerns on embodiment of this invention. 2A and 2B are diagrams for explaining an electronic governor according to an embodiment of the present invention, in which FIG. 2A is a graph illustrating engine rotation fluctuation and dither width, and FIG. It is an enlarged view. It is the figure which showed the hysteresis characteristic of the actuator. It is a figure which shows that the hysteresis width of an actuator increases at the time of cold.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electronic governor 2 ... Actuator 3 ... Speed detection means 4 ... Target speed setting means 5 ... Drive current control means 6 ... Dither current superposition means 7 ... Drive means 8 ... Disturbance discrimination means

Claims (1)

By controlling the actuator drive current that drives the actuator (2), the actuator (2) operates the fuel metering means, and the fuel metering means adjusts the fuel supply amount so that the engine speed approaches the target speed. Let
A rotation speed detection means (3) for detecting the rotation speed of the engine, a target rotation speed setting means (4) for setting the target rotation speed, and the actuator drive current are controlled so that the rotation speed of the engine approaches the target rotation speed. Drive current control means (5), dither current superimposing means (6) for superimposing the dither current on the actuator drive current, and drive means (7) for outputting the actuator drive current with the dither current superimposed on the actuator (2) In the electronic governor of the equipped engine,
Disturbance determining means (8) for determining that the dither is a control disturbance is provided, and the disturbance determining means (8) is linked to the rotation speed detecting means (3) and the dither current superimposing means (6),
The disturbance determination means (8) calculates the time difference Δt and the rotation speed difference ΔR between adjacent peaks of the engine speed fluctuation, the time difference Δt is less than the predetermined time difference t, and the rotation speed difference ΔR is the predetermined rotation speed difference R. When the above number of times continues for a predetermined number n or more, the disturbance determination means (8) determines that the dither is a control disturbance, and based on this determination, the dither current superimposing means (6) An electronic governor for an engine, wherein the dither width of the dither current is reduced.

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