JPS642776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a governor device applied to a diesel engine.

[Problems to be solved by conventional technology and invention]

When a diesel engine is operating as an all-speed governor (constant rotational speed) and a sudden load is applied, the engine rotational speed -
The rotational speed decreases from point A to point B on the engine's output torque characteristic curve, and this results in the engine being evaluated as a "sluggish engine." In addition, in a turbocharged engine, the engine moves from point A to point B as shown in the broken line, as shown in Figure 2, giving a feeling of sluggishness.
This is because when the load is light, the engine exhaust temperature is low, so the rotation speed of the turbocharger does not increase, and the intake air is hardly supercharged. This is because in such a state, even if a load is suddenly applied and fuel is increased, the rotational speed of the turbocharger does not increase immediately. When such a phenomenon occurs, work efficiency decreases and the burden on the operator increases.

In view of these circumstances, this invention improves work efficiency by preventing the engine rotation speed from changing significantly in response to sudden actual load changes.
The purpose of the present invention is to provide a governor device that reduces the burden on the operator.

[Means to solve the problem]

Therefore, in this invention, the target engine rotation speed
Control rack position command signal set based on the deviation ΔEa between Es and actual engine speed En
Esa is compared with the control rack position limit signal _ELS , which is set based on the actual engine speed En and the rated torque characteristics, and the smaller signal E is used to control the fuel injection pump. In a governor device for controlling the position of a rack, a first change rate detection means for differentiating the control position command signal Esa to detect a time change rate E'sa (=dEsa/dt) of the signal Esa; a first comparison means that outputs a timer activation signal when the rate of change E′sa exceeds a first set value Ed; and a predetermined time period is set in advance and is activated by the timer activation signal. a first timer means; a signal adding means for adding a preset value Eo to the control rack position limit signal _ELS only while the first timer means is operating; and a signal adding means for differentiating the target engine speed Es. a second change rate detection means for detecting a time change rate dEs/dt of the signal Es; and a time change rate dEs/dt detected by the second change rate detection means is equal to or higher than a second set value Ea. a second comparison means that outputs a timer activation signal when the second comparison means reaches a predetermined time, and a second timer means that is activated by the timer activation signal that is set in advance for a predetermined time and is output from the second comparison means; The apparatus further includes a function stopping means for stopping the function of the signal adding means only while the second timer means is performing a time counting operation.

[Effect]

According to this configuration, when a sudden load occurs,
Since the control position command signal Esa suddenly rises, its time change rate E′sa increases, and E′sa≧
Ed, and a timer activation signal is output from the first comparing means. Therefore, the first timer means is activated and the preset value Eo is added to the control rack position limit signal _ELS by the signal applying means only during the preset clocking time of the timer means. As a result, when there is a sudden load, the addition result E _LS +Eo is compared with the actual engine speed En, and the control rack position of the fuel injection pump is controlled based on the smaller signal E of these. That is, when a sudden load occurs on the engine, the engine output torque limit is relaxed and the engine outputs torque greater than the limit torque for a certain period of time, thereby preventing the engine rotational speed from decreasing.

Furthermore, in this invention, the second change rate detection means detects the time change rate of the target engine rotational speed Es.
dEs/dt is detected, and this detected value dEs/dt is the set value.
When dEs/dt>Ea, the function of the signal addition means is stopped by the operation of the function stop means for a preset time measured by the second timer means, and when dEs/dt>Ea, the addition result E _LS +
The control rack position control based on the comparison between Eo and the actual engine rotation speed En is prohibited, and at this time, the rack position control is executed as usual by comparing the control rack signal _ELS and the actual engine rotation speed En. In other words, when the throttle is moved frequently, the target engine speed Es also fluctuates greatly.
As a result, the control rack position command signal Esa also fluctuates. Therefore, during such work, a timer activation signal is output from the first comparing means, leading to an erroneous determination that a sudden load has been applied. Therefore, by the second comparison means,
A sudden displacement of the throttle is detected by detecting dEs/dt>Ea, and in such a case, the above-mentioned rack position control for sudden loads is prohibited.

〔Example〕

The present invention will be described in detail below based on an embodiment of the accompanying drawings.

Engines generally have a short-time rating that can be higher than a continuous rating. Therefore, by taking advantage of this, the output torque limit is relaxed for short-term sudden loads, that is, the amount of fuel injection is increased, the output torque of the engine is increased, and the rotational speed is not reduced. be able to. This can be explained using the torque-rotational speed characteristic curve as follows. Now, if the load pattern is expressed as shown in Figure 3, it is determined that a sudden load is applied when moving from point A to point B, and the output torque limit is raised to reach the position shown by the solid line in Figure 4. Place the item at the position indicated by the dashed line. Then, what would normally move to point C will now move to point B, making it possible to suppress the rate of speed fluctuation to an extremely low level. Next, after a while, the load shown in Figure 3 changes from point B to point A.
When it moves to the point, it returns to point A in FIG. 4 again. In addition, when the load pattern is as shown in Fig. 5, when the load moves from point A to point B, it moves from point A to point B as shown by the broken line in Fig. 4, but for a certain period of time t ₁ If the load does not decrease even after the above period has passed,
The engine is moved to point C (on the solid line in FIG. 4), which is within the continuous rating range of the engine, to prevent engine overload.

FIG. 6 is a block diagram showing an embodiment of the present invention, in which the actual rotational speed Ne of the engine 1 is detected as a pulse signal Pn of a corresponding frequency by an electromagnetic pickup coil 4, and this pulse Pn is detected by a frequency-voltage converter 31. Convert and output to the corresponding signal En. on the other hand,
The position of a throttle lever (not shown) is detected by a throttle sensor 3 to obtain a target engine rotational speed command signal Es corresponding to the lever position. Then, the deviation ΔEa between the signals Es and En is passed through the PID compensation circuit 33 to maintain control responsiveness and stability, and a control rack position command signal Esa is obtained. As is well known, the position of the control rack 2a provided in the fuel injection pump 2 determines the amount of fuel injected, and the amount of fuel injected determines the output torque of the engine.

The solid line in FIG. 7 is the rated torque characteristic of the engine 1, that is, the characteristic indicating the permissible value of the output torque of the engine, and this is also the rack position limit characteristic that sets the upper limit of the position of the control rack 2a.

The function generator 32 calculates, based on the actual engine speed Ne (En in terms of voltage) and the relationship shown in FIG.
It functions to output a control rack position limit signal _ELS corresponding to the rotational speed Ne.

The minimum signal priority circuit 34 compares the input signal Esa and _ELS , and when Esa> _ELS , the signal _ELS is set as Esa.
When ≦E _LS , signal Esa is output. In this manner, the control rack position command signal is prevented from exceeding the torque limit value. The signal E output from this minimum signal priority circuit 34 is
This is a position command signal for the control rack of the injection pump 2 which determines the injection amount.When the signal E becomes large, the amount of fuel injected from the injectors 1a to 1b is increased, and when it becomes small, it is decreased.
The deviation ΔEb between this command signal E and the position signal e _L output from the control rack position detector 10 is
Compensate in the same manner as described above through the PID compensation circuit 35,
Obtain command signal _ELC . After this signal E _LC is amplified by the amplifier 36, it is added to the control rack driving solenoid 20, and is then applied to the control rack 2a.
control the position of

Now, if the minimum signal priority circuit 34 were not present, the output signal Esa of the PID compensation circuit 33 would directly serve as the position command signal for the control rack 2a of the injection pump 2. Therefore, this signal Esa is used to detect sudden loads.

If a sudden load is applied to engine 1, the signal Esa
Since the value increases rapidly, the differentiator 41 calculates this change over time.
(first rate of change detection means), and a signal E'sa (=dEsa/dt) corresponding to the rate of change is determined. The comparison circuit 42 (first comparison means) receives this differential signal.
E'sa is compared with the reference signal Ed, and when E'sa≧Ed, a signal is output to operate the timer 43 (first timer means), and the switch 44 is turned on for a predetermined period of time. By inputting the signal Eo to the adder 70 through 44, a predetermined signal Eo is added to the output signal _ELS of the function generator 32. in short,
When E′sa≧Ed, E _LS +Eo (only for a certain period of time) is established (indicated by the broken line in Fig. 7). In addition, switch 4
4 and the adder 70 correspond to signal providing means in the claims. Since this signal (E _LS + Eo) becomes the torque limit value, the minimum signal priority circuit 34 selects the signal (E _LS + Eo) when the input signal is Esa>E _LS + Eo.
When Esa≦E _LS +Eo, the signal Esa is output. When a sudden load is applied to engine 1, the actual engine speed Ne decreases, so Esa>E _LS +Eo
Therefore, the output of the minimum signal priority circuit 24 is E=E _LS +Eo. Therefore, when a sudden load is applied, the fuel injection amount is increased for a certain period of time compared to normal times, thereby increasing the engine torque and preventing the rotational speed of the engine 1 from decreasing.

By the way, with construction machinery such as bulldozers, there is no problem because the engine rotation command value is fixed at an almost constant throttle during work, but if the throttle is moved frequently, the PID compensation circuit 33
The output voltage Esa may fluctuate, and the same judgment may be made as if a sudden load had been applied. Therefore, in order to prevent this, the signal Es indicating the target engine rotational speed is converted to a differentiator 51 (second rate of change detection means).
The signal E′s (=
dEs/dt) is detected and added to the comparison circuit 52 (second comparison means), and the comparison circuit 52 detects that this value E's exceeds a predetermined value Ea, and the timer 53 (second timer means) is detected. ) for a certain period of time and switch 54.
(function stop means) is turned off so that the signal Eo is not added to the signal _ELS even if the switch 44 is on. Therefore, it is possible to increase the amount of fuel in the engine 1 only when there is a real sudden load without being affected by the movement of the throttle.

〔Effect of the invention〕

As explained above, according to the present invention, when a load is suddenly applied, the output torque limit is relaxed, the fuel injection amount is increased to increase the engine output torque, and the target engine rotation corresponding to the throttle amount is increased. If the time rate of change of the speed command signal exceeds a certain value, control to increase the injection amount is prohibited for a certain period of time, so the engine rotation speed does not change even under sudden load changes. This makes it possible to improve work efficiency and reduce the burden on the operator, and furthermore, the above-mentioned increase control can be performed only when a real sudden load is actually applied.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing engine torque-revolution speed characteristics, Figure 3 is a diagram showing load patterns,
Fig. 4 is a diagram showing the torque-rotational speed characteristic of the engine, Fig. 5 is a diagram showing the load pattern, Fig. 6 is a block diagram showing one embodiment of the governor device according to the present invention, and Fig. 7 is a diagram showing the engine rotation. FIG. 3 is a diagram showing the relationship between speed voltage and control rack limit value. 1... Engine, 2... Injection pump, 3... Throttle sensor, 4... Pick up coil, 1
0... Control rack position detector, 32...
Function generator, 33, 35...PID compensation circuit, 4
1, 51... Differentiator, 42, 52, 61... Comparison circuit, 43, 53... Timer, 44, 54, 62
...Switch.

Claims (1)

[Claims] 1. A control rack position command signal that is set based on the deviation between the target engine speed and the actual engine speed, and a control rack that is set based on the actual engine speed and the rated torque characteristics. In a governor device that controls the position of a control rack of a fuel injection pump by comparing two position limit signals and using the smaller of the two signals, the first controller detects a rate of change over time of the control position command signal. a rate of change detection means; a first comparison means for outputting a timer activation signal when the time rate of change exceeds a first set value; a first timer means that is activated when the timer is activated; a signal adding means that adds a preset value to the control rack position limit signal only while the first timer means is in a timing operation; and a time change in the target engine rotational speed. a second rate of change detection means for detecting the rate of change; and a second comparison unit that outputs a timer activation signal when the time rate of change detected by the second rate of change detection means exceeds a second set value. means, a second timer means that is preset for a predetermined time and is activated by a timer activation signal output from the second comparison means, and only while the second timer means is in a timekeeping operation. A governor device comprising function stopping means for stopping the function of the signal adding means.