JPH0318675Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a horsepower control system for a diesel engine loaded with a hydraulic pump.

A diesel engine uses a speed governor to suppress changes in rotational speed due to load fluctuations, and FIG. 1 shows an example of this speed governor.

In this speed governor, if the adjuster steering lever 1, which is linked to a throttle lever (not shown), is operated to the highest speed position (full throttle position) shown in the figure, in this operating position, the lever 1 and the tension lever The tension of the control spring 3 interposed between the two is very strong.
Therefore, the lower end of the tension lever 2 strongly presses the control block 4 to the left. At this time, the control lever 6 is located at a position where the centrifugal force of the flyweight 5 rotated by the engine (not shown) and the tensile force of the control spring 3 are balanced, and the control lever 6 is thereby The control rack 7 associated with 6 is placed in the full load position shown.

The control rack 7 controls the fuel injection amount of an injection device (not shown), and when moved in the direction of arrow A, the injection amount increases, and when moved in the direction of arrow B, the injection amount decreases. do.

Now, when the engine speed becomes higher than the specified rotation speed _N0 set by the position of the adjuster steering lever 1, the centrifugal force caused by the fly weight 5 becomes larger than the tensile force of the control spring 3, so the tension The lower end of the lever 2 is moved to the right by the control block 4, and at the same time the guide lever 8 is also moved to the right. Therefore, the upper end of the control lever 6 moves the lever in the direction B that reduces the amount of fuel injected, and as a result, the engine speed is returned to the specified speed _N0 . Note that when the load increases and the engine speed becomes lower than the specified rotation speed, the control block 4 is moved to the left because the centrifugal force acting on the flyweight 5 is small. Therefore, the rack 7 is moved via the control lever 6 in the direction A for increasing the injection quantity, thereby raising the engine speed to the specified speed _N0 .

FIG. 3 shows an example of the relationship between engine rotation speed and generated horsepower. For example, when the adjuster steering lever 1 is operated to the maximum speed position shown in FIG. As a result, the engine speed is maintained at approximately the specified value N ₀ .

Next, when the adjuster steering lever 1 is operated to the partial position shown in FIG. 2 via the throttle lever, the control spring 3
Since the tension becomes weaker, the force that urges the tension lever 2 to the left becomes smaller. As a result, the fly weights 5 open wide and move the control block 4 to the right, thereby moving the control lever 6, ie, the rack 7, in the direction of reducing the injection amount as shown. The rack 7 is then stopped at a position where the centrifugal force acting on the flyweight and the tensile force of the control spring 3 are balanced. In other words, at the operating position of the adjuster steering lever 1 shown in FIG. 2, the flyweight 5 opens at low rotation speeds, so the engine rotational speed will eventually reach N shown in FIG. 3 corresponding to the operating position of the lever 1. ₁ rotation (no-load idle rotation speed)
is set to If the engine rotation becomes larger or smaller than N ₁ due to the magnitude of the load, the control rack is set so that the engine rotation becomes N ₁ by the action of the fly weight 5 in the same way as described above. 7 is controlled.

By the way, when the adjuster steering lever 1 is operated from the full throttle position shown in Fig. 1 to the partial position shown in Fig. 2, if PS ₀ is the maximum horsepower generated at full throttle and PS ₁ is the maximum horsepower generated at partial, then As shown in Figure 3, the horsepower of the engine decreases by ΔPS=PS ₀ -PS ₁ , and along with this, the fuel consumption also decreases by (ΔPS/PS ₀ )×100%. Therefore, under light loads where there is no problem even if the generated horsepower decreases, it is conceivable to operate the adjuster steering lever 1 to the partial position to reduce fuel consumption. Construction machinery such as a power shovel that operates an actuator for driving a working machine such as a hydraulic cylinder with hydraulic oil discharged from the hydraulic pump has the following disadvantages.

That is, when the hydraulic pump is driven with engine output horsepower PS ₀ when the engine rotation speed is N ₀ , the ranges in which the hydraulic oil discharge flow rate and discharge pressure of the pump can change are A, B, and A in FIG. This area is within the range connecting points C, D, and E, and when the above hydraulic pump is driven with engine output horsepower PS ₁ when the engine speed is N ₁ , the same area is AB′C′D′ in the figure. It is within the range connecting point E.

As shown in the figure, when the adjuster steering lever 1 is operated to the partial position, the maximum discharge flow rate of the pump becomes smaller by N ₁ /N ₀ than when the lever 1 is operated to the full throttle position. , if the discharge flow rate of the above pump when the swash plate angle is maximized is q (cc/rev), then the discharge flow rate Q (cc/min) of the pump is Q∞q×N...(1) However, This is also clear from the fact that N is expressed by the engine speed.

For the above reasons, when the adjuster steering lever 1 is changed from the full throttle position to the partial position, fuel consumption can be reduced, but the maximum discharge flow rate of the pump is restricted. This restriction of the discharge amount lengthens the cycle time of an actuator driven by the oil discharged from the pump, such as a cylinder for driving a work machine of a power shovel, thereby impairing the operability of the work machine.

In view of this, an object of the present invention is to provide a horsepower control device for a diesel engine that can reduce the horsepower generated by the engine without limiting the maximum discharge flow rate of the pump.

Therefore, the present invention includes a throttle lever that sets the target engine speed, a flyweight that rotates in accordance with the engine speed, a force corresponding to the target speed set by the throttle lever, and a centrifugal force of the flyweight. a block member that is moved to a position where the force is balanced; a control rack that is connected to the block member and controls the fuel injection amount according to the moved position; and the block member is moved to a position that corresponds to the maximum displacement position of the control rack. a speed governor equipped with a full load stopper for regulation, an engine rotation detection means for detecting engine rotation speed, and a hydraulic pump driven by the engine and whose discharge amount is controlled by controlling a swash plate angle. and a control means for variably controlling the swash plate angle of the hydraulic pump based on the deviation between the target rotation speed set by the throttle lever and the detected value of the engine rotation detection means. In the apparatus, an economy switch and a control rack forced moving means for forcibly moving the relative position of the control rack of the speed governor with respect to the block member by a predetermined amount in a direction in which the fuel injection amount is decreased by turning on the economy switch. and

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 5 shows an embodiment of a horsepower control device according to the present invention applied to a construction machine such as a power shovel.

In the figure, a diesel engine 10 includes a fuel injection pump 12 equipped with a speed governor 11, and the output shaft of the engine is connected to the input shafts of hydraulic pumps 13 and 14. The adjuster steering lever 1 of the speed governor 11 is connected to a throttle lever 15 provided in the operator's room, and one end of a maximum easy displacement position regulating lever 16, which will be described later, is connected to a solenoid 17. Note that the hydraulic oil discharged from the pumps 13 and 14 is supplied to a hydraulic actuator (hydraulic cylinder, hydraulic motor) that drives a working machine of a construction machine.

The potentiometer 18 detects the operating angle of the throttle lever 15, that is, the adjuster steering lever 1, as an electric signal, and the rotation speed detector 19 detects the rotation speed of the output shaft of the engine 10 as an electric signal. It is something to do. Further, servo mechanisms 20 and 21 attached to the hydraulic pumps 13 and 14 respectively position the swash plate angles of the pumps 13 and 14 at an angle corresponding to the magnitude of the input signal.

The control circuit 22 has a built-in means for calculating the deviation between the output signal S ₁ (engine rotation speed command signal) of the potentiometer and the output signal S ₂ of the rotation speed detector 19, and uses the deviation signal S ₃ as described above. Servo mechanism 20, 2
1 as a swash plate control signal. The control circuit 22 also incorporates means for energizing the solenoid 17 when the economy switch 23 is turned on.

Next, lever 1 for regulating the maximum easy displacement position mentioned above.
6 will be explained with reference to FIGS. 6 to 8. In each figure, the same elements as those shown in FIG. 1 are given the same reference numerals.

As shown in FIG. 6, the lever 16 has a substantially L-shape, and a U-shaped notch 16a, shown enlarged in FIG. The lower ends of the two are fitted and engaged. Therefore, when the solenoid 17 is energized, the lever 16 is rotated by a predetermined angle to the left about its rotation fulcrum 24 as shown in FIG. 8, and thereby the control lever 6 is rotated. It is rotated to the right about the fulcrum 25. As a result, the control rack 7 is moved to the right, and the amount of fuel injected by the injection device 12 is accordingly reduced. That is, solenoid 17
When energized, the position of the rack 7 is moved by a predetermined amount in the direction of decreasing the fuel injection amount from the position determined by the position of the block member at that time, and in this embodiment, this movement is quantity is first
The lever ratio of the lever 16 is set so as to provide the moving distance from the full load position shown in the figure to the partial position shown in FIG. 2. 6 and 8, 100 is a full load stopper that regulates the position of the control rack 7 to the maximum displacement position, and this full load stopper 100 has the conventional structure shown in FIGS. 1 and 2. are also provided.

The operation of the device shown in this example is as follows. That is, when the economy switch 23 is not turned on, the lower end rotation point of the control lever 6 in the speed governor 11 shown in FIG. 6 is at the same position as that of the speed governor shown in FIG. Therefore, both speed governors perform exactly the same speed governing operation. In other words, the speed regulating operation is performed so that the rotational speed of the engine 10 becomes the value N ₀ shown in FIG. 3.

Next, when the economy switch 23 is turned on by the operator, the solenoid 17 is energized and the rack 7 is moved to the position shown in FIG. As a result, the amount of fuel injected decreases and the rotational speed of the engine 10 decreases, but since the throttle lever 15 is not operated at this time, the value of the output signal _S1 of the potentiometer 18 is equal to the engine rotational speed. N is held at a value that commands ₀ . Therefore, the control circuit 22 outputs a signal _S3 indicating the deviation between the commanded rotational speed _N0 and the decreased engine rotational speed, and this signal _S3 indicates that the decreased engine rotational speed becomes the commanded rotational speed _N0 . As above pump 1
Controls the swash plate angles 3 and 14.

In the governor shown in FIG. 1, the engine speed is uniquely set by the operating position of the adjuster steering lever 1.
is moved to the position shown in FIG. 2, it is impossible to maintain the engine speed at the above value N ₀ even if the swash plate angles of the pumps 13 and 14 are controlled as described above. That is, in the operating state of the rack shown in FIG. 2, when the swash plate angle of the pump is controlled to increase the engine speed, the engine speed increases to the
Since the rack 7 is shifted to the right so as to reach the value N ₁ shown in the figure, it is not possible to maintain the engine speed at the value N ₀ .

On the other hand, according to the device of the above embodiment, in the operating state of the rack shown in FIG. 8, the control spring 3 pulls the tension lever 2 with the same strength as in the case of FIG. Therefore, the number of revolutions of the engine is not limited to the above _N1 revolutions. Therefore, by controlling the swash plates of the pumps 13 and 14, it is possible to maintain the engine speed at the specified rotation speed _N0 while reducing the engine horsepower, and FIG. 9 shows this effect. ing.

When the engine speed is maintained at N ₀ with the horsepower reduced as described above, the pump 1
The range in which the hydraulic oil discharge flow rate and discharge pressure of Nos. 3 and 14 can change is within the range connecting points A, B'', C'', D, and E in Fig. 10, and therefore these pumps have their maximum discharge amount. Q _MAX can be secured. Therefore,
According to the device of this embodiment, the pumps 13, 14
Fuel consumption can be reduced without affecting the cycle time of a hydraulic actuator operated by discharged oil.

Note that the lever 16 has the function of regulating the maximum displacement position of the control rack 7 in the A direction (injection amount increasing direction), so any lever having the same function may be used instead. can. That is, for example, the rod 26 connecting the control rack 7 and the control lever 6
The maximum displacement position may be regulated by configuring the length to be changed by an external operation. Of course, in that case, the lower end of the control lever 6 is pivoted at a predetermined position as shown in FIG.

Further, in the above embodiment, the lower end position of the control lever 6 is changed by the lever 16 and the solenoid 17, but the lower end position of the lever 6 is changed continuously by an electric motor or an electro-hydraulic servo mechanism. It is also possible to do
In this way, a wider range of engine horsepower control can be performed in accordance with the size of the load.

The present invention can of course be applied to engines equipped with other types of governors such as pneumatic governors.

According to the horsepower control device for a diesel engine according to the present invention, the horsepower of the engine is reduced without changing the rotational speed of the engine, that is, while ensuring the maximum discharge amount of the hydraulic pump driven by the engine. can be done. Therefore, it is possible to save fuel consumption without affecting the cycle time of the hydraulic actuator operated by the oil discharged from the hydraulic pump. Note that the horsepower and fuel consumption wg per hour are the same when the economy switch 23 shown in the example is turned on and when it is not turned on, so when the above switch is turned on, W x ΔPS (g/h) of fuel can be saved.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing the configuration and operation of a conventional speed governor, respectively. Figure 3 is a characteristic diagram showing the relationship between engine speed and generated horsepower and the function of the speed governor. Figure 4 is a characteristic diagram showing the relationship between the discharge flow rate and discharge pressure of the hydraulic pump based on the action of the governor shown in Figure 1, and Figure 5 conceptually shows an embodiment of the control device according to the present invention. The illustrated block diagram, FIGS. 6 and 8 are diagrams showing an example of the speed governor according to the present invention and its operating mode, and FIG. 7 shows the engagement relationship between the control lever and the lever for regulating the maximum easy displacement position. FIG. 9 is a characteristic diagram showing the relationship between the engine speed and generated horsepower when the speed is controlled by the control device according to the present invention, and FIG. FIG. 2 is a characteristic diagram showing the relationship between the discharge flow rate and the discharge pressure of the hydraulic pump when the horsepower of the engine is controlled by the device. 1...Adjustment lever, 2...Tension lever, 3...Control spring, 5
... Fly weight, 6 ... Control lever, 7 ... Control rack, 10 ... Engine, 11 ... Speed governor, 13, 14 ... Hydraulic pump, 15 ... Throttle lever, 16 ... Maximum rack displacement Position regulating lever, 17... solenoid, 18... potentiometer, 19... rotation speed detector, 20, 21... servo mechanism, 22... control circuit, 23... economy switch.

Claims (1)

[Claims for Utility Model Registration] A throttle lever that sets a target engine speed, a flyweight that rotates in accordance with the engine speed, a force that corresponds to the target speed set by the throttle lever, and the flyweight. a block member that is moved to a position where the centrifugal force of the block member is balanced with the centrifugal force of the block member, a control rack that is connected to the block member and controls the fuel injection amount according to the moved position, and a control rack that moves the block member to a maximum position of the control rack. a speed governor equipped with a full load stopper for regulating the engine position; an engine rotation detection means for detecting the engine rotation speed; A diesel engine comprising: a hydraulic pump; and a control means for variably controlling a swash plate angle of the hydraulic pump based on a deviation between a target rotation speed set by the throttle lever and a detected value of the engine rotation detection means. In a horsepower control device, an economy switch is provided, and a control rack forcibly moves the relative position of the control rack of the speed governor with respect to the block member by a predetermined amount in a direction in which the amount of fuel injection is decreased by turning on the economy switch. A means of transportation, and a horsepower control device for a diesel engine, comprising: