JPS6393637A - Car speed control device for working machine - Google Patents

Abstract

PURPOSE:To provide number-of-revolutions control of high precision by incorporating such an arrangement that the number of engine revolutions is retained at a set value through adjustment of the amount of supplied fuel according to the engine load, and therein electrically controlling the speed change ratio of a speed change means for running in accordance with the load. CONSTITUTION:In a working machine 1 in which wheels are driven by an engine 2 through a speed change device for running 3, the device 3 is controlled by a control part 15 together with an electronic governor 5 furnished on a fuel injection pump 4. This control part 15 is equipped with a ROM 19 to store the relationship between the number of engine revolutions sensed by a rotation sensor 8 and the engine output in the form of output characteristics in accordance with the magnitude of the load. The range nipped by two adjoining ones among those output characteristics is specified, and the speed change ratio of the speed change device for running 3 is altered in accordance with the actual load sensed so that operation in the selected range is maintained with the set number of engine revolutions.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a vehicle speed control device for a working machine that automatically changes vehicle speed according to load.

<Conventional technology> Generally, in working machines such as agricultural machinery and construction machinery,
The built-in internal combustion engine is used as a power source to drive and perform various tasks, and when you want to perform work while moving at the same time, you may want to perform PT○ work at a constant speed even if you sacrifice vehicle speed. Not a few.

For example, Japanese Patent Application Laid-open No. 6
No. 1-6026 proposes detecting the load based on the engine speed and the accelerator position, and shifting the automatic transmission means to maintain the engine speed within a predetermined range.

<Problems to be solved by the invention> In the device proposed above, a mechanical so-called all-speed governor is used as the governor, or detecting the load from the engine speed and accelerator position is All-speed governors with small number changes have poor accuracy and may be difficult to control properly.

Figure 11 shows an example of load detection when driving in the intermediate range, where A is the no-load rotation speed at the recognized accelerator position, and B
is the actual rotational speed, C is the output characteristic relative to the rotational speed at the recognized accelerator position, D is the output characteristic relative to the actual rotational speed, and E
is the load recognized from the actual rotation speed, and F is the actual load. That is, there is a discrepancy between the actual accelerator position and the load, which tends to cause detection errors.

Furthermore, it is difficult to maintain a constant engine speed with a mechanical governor, and from this point of view as well, it is not suitable for performing accurate control.

This invention focuses on the above-mentioned problems, and when the load fluctuates during work, it automatically changes the gear ratio and changes the traveling speed to deal with the load fluctuation, thereby stabilizing PTO workability. This was done with the purpose of providing a work machine that can perform work at high speed.

<Means for Solving the Problems> In order to achieve the above object, the vehicle speed control device for a working machine of the present invention detects the engine load based on the engine rotation speed and fuel supply amount, and adjusts the fuel consumption according to the load. A running gear that can electrically control the gear ratio in a working machine equipped with an electric control means that adjusts the supply amount and maintains the engine speed at a constant value set by the accelerator. storage means for storing the relationship between engine speed and output in the form of a plurality of output characteristics according to the magnitude of load; and an area sandwiched between two adjacent output characteristics among the plurality of output characteristics. a characteristic selection means for specifying the engine speed, and a transmission ratio control means for changing the transmission ratio of the traveling transmission means in accordance with the detected actual load so as to maintain operation in the selected range at the set engine speed. , and is equipped with.

Since the amount of fuel supplied is a direct reflection of the load on the engine, the current load can be detected without error by detecting the engine speed and the amount of fuel supplied. Since the automatic control means is used, control to keep the rotational speed constant is performed with high precision. An example of such electrical control is, for example, Japanese Patent Laid-Open No. 61-72846. In addition, since the gear ratio of the driving transmission is electrically controlled according to the load, changes in vehicle speed are made appropriately and the selected output characteristics are maintained, resulting in a constant speed unaffected by load fluctuations. It becomes possible to work in

<Example> Hereinafter, an illustrated example of a working machine equipped with a diesel engine will be described.

[A) Overall configuration and basic control In the conceptual system diagram in Figure 1, 1 is the working machine, 2 is the engine,
3 is a transmission for driving; 4 is a fuel injection pump for the engine 2; 5 is a rack actuator 6; and a rack position sensor 7.
, an electronic governor equipped with a rotation sensor 8, etc.; 9 is an accelerator;
10 is an accelerator position sensor, 11 is a cooling water temperature sensor, 1
2 is a fuel temperature sensor.

Reference numeral 15 denotes a control unit, which controls the operating state of the engine according to instructions from the operator. For example, a microcomputer is used as this control unit, including an input port 16 into which various signals are input, and a C which provides control calculations and input/output instructions.
RAM1 used for control calculations of PU17 and CPU17
8. ROM that stores control programs and score data necessary for control calculation] 9. Traveling transmission 3 and electronic governor 5
It is composed of an output port 20 and the like to which a control output is output.

The traveling transmission 3 has a structure in which the gear ratio can be controlled electrically, and is, for example, a hydraulic clutch type transmission as shown in FIGS. As the electronic governor 5, for example, one having a structure as shown in FIG. 2 of the above-mentioned Japanese Patent Laid-Open No. 61-72846 is used.

The control unit 15 also controls the engine 2 and the working machine 1 as a whole, and receives various signals in addition to signals from the sensors 11 and 12, and outputs various control outputs other than those described below. It is configured to be output from the port.

The ROM 19 contains the set value of the engine speed, which is arbitrarily set by the position of the accelerator operated by the operator's will, and the speed fluctuation rate characteristic, which shows how the actual speed (actual value) changes depending on the load. , the required speed fluctuation rate characteristics are stored in the form of arithmetic expressions or numerical tables for each work content. The case of the numerical table will be explained below. Table 1 is the first numerical table (hereinafter referred to as droop rate map)
In this example, Dl at the intersection of the set value N5et and the actual value Nact indicates the droop coefficient in each case.

In addition, Table 2 defines the relationship between the no-load idling rotation speed N1dl corresponding to the set value N5et and the rack position corresponding to this, that is, the no-load equivalent rack position Ridl.
The no-load equivalent rack position map shown in Table 3 and the maximum rack position map shown in Table 3 determined to limit the maximum injection amount at each rotation speed are stored in the ROM 19, respectively.

Note that even if N1dl in Table 2 above is replaced with N5et, and Nmax in Table 3 is replaced with Nact, they are substantially the same.

=7- As mentioned above, droop rate maps are created for each of a plurality of control modes with different speed fluctuation rate characteristics, but in order to simplify the explanation below, 1=1 and i=2, that is, control A case will be described in which two maps, mode 1 and control mode 2, are used. In Figure 1,
Reference numeral 13 is a mode selection switch for selecting a predetermined one from among these multiple modes, and the selection instruction is recognized by the on/off state of the switch and is made by logical judgment on the control program, and one of the modes is always selected. It has the ability to select one mode.

Next, the operation will be explained with reference to the control flowchart shown in FIG.

Various signals for recognizing the state of the engine are converted into recognizable signals at the input port 16 and input to the CPU 17 . The CPU 17 then performs control calculations according to a predetermined program and outputs various control signals.

Regarding the speed fluctuation rate, as shown in Fig. 2, first recognize the set value N5et and actual value Nact of the engine speed, -8.1 Also read the no-load equivalent rack position Ridl from Table 2,
Next, the state of the mode selection switch 13 set by the operator is read, and the target rack position Rset to be set is calculated based on the droop rate map of i=1 or i=2 depending on the mode.

This target rack position Rset is the set value N of the engine rotation speed.
corresponding to the target fuel supply amount for obtaining a predetermined actual value Nact for set, the detected N act
Using the droop coefficient Di found from Table 1 from set and Nact and Table 2, use the following calculation formula % Formula % Next, read the maximum rack position Rmax from Table 3 and compare it with the R set just found. Rset > Rma
If not, a control signal is output from the control unit 15 to the rack actuator 6 to set the actual rack position Ract to Rset, and if Rset>Rmax, a control signal is outputted to the rack actuator 6 so that the rotation speed does not exceed the allowable value. to Rs.
et = Rmax, and the actual rack position Rac
A control signal for setting t to the corrected target rack position Rset is output. In this way, the rack position of the fuel pump 4 is automatically adjusted, and the fuel pump 4 is operated at a predetermined speed fluctuation rate.

The plurality of speed variation @ rate characteristics in the above explanation are selected depending on the work content, and in this invention, control mode 2 is a constant speed control characteristic with a speed fluctuation rate of zero, and when this characteristic is selected, will be implemented.

Such constant speed control is used for work that requires constant speed operation, such as rotary, plowing, potato digging, and the like.

In this way, when one of the control modes is a constant speed characteristic,
Although one of the maps shown in Table 1 may have a constant speed characteristic with no speed fluctuations, an example using the correction coefficient N5ift will be described next.

FIG. 3 shows the control mode selection procedure,
Constant speed control is based on the assumption that the operator is not operating the accelerator, so when the mode selection switch 13 is set to mode 2, it is first checked whether the accelerator is fixed, and if the accelerator is fixed. If the accelerator is being accelerated or decelerated, mode 1 droop control is selected regardless of the mode selection switch 13.

When mode 2 is selected, as shown in FIG. 4, the set value N set and the actual value Nact are first compared, and the corrected set value N5et' is determined by the following arithmetic expression %. The correction coefficient N5ift is a value that is set in advance through preliminary experiments depending on the structure and rating of the engine. Next, the target rack position Rset is calculated in the same manner as in FIG. 4, but when N5et' is determined, this N5et' is used instead of the set value Nset set by the accelerator.

In this way, the rack is moved to the target rack position based on the corrected set value, and constant speed control is performed.

(B) Control according to the present invention In FIG. 5, zl, z2, and Z3 are preset load ranges, and are used for deceleration solar, appropriate solar, and
Indicates the speed increase zone. This invention changes the gear ratio of the traveling transmission 3 according to the load when constant speed control is performed according to the above procedure, and keeps the speed of PTO operation constant. In the example, suitable solar z2
is selected.

For this reason, the ROM 19 stores a deceleration instruction load rate map as shown in Table 4 below, and an acceleration instruction load rate map as shown in Table 5, and these maps are used to perform the following operations. Control takes place. The deceleration instruction load rate map in Table 4 and the acceleration instruction load rate map in Table 5 are based on the boundary line between the deceleration zone Z1 and the appropriate solar Z2 shown by the dashed line in FIG.
and the boundary line between the proper zone Z2 and the speed increase zone z3 shown by the two-dot chain line, respectively.

=12- First, as shown in Figure 6 (8), the actual value N of the engine speed
act and the actual rack position Ract, calculate the no-load equivalent rack position Ridl and the maximum rack position Rmax from Tables 2 and 3, and calculate the load factor L a at that time using the following formula.
ct is required. Note that the intermediate values in the table are determined by interpolation calculations.

Rmax-Ridl Next, as shown in FIG. 6(b), the actual value of the rotation speed N a
ct is applied to Tables 4 and 5, and the load factors Vdown and Vup, which are the criteria for determining whether the load factor for the rotational speed at that time exceeds the allowable value, are determined. The intermediate values in the table are determined by interpolation calculations.

Thus obtained L act, Vdown and Vup
The vehicle speed is controlled using the procedure shown in FIG.

That is, the load factor L act at that time is compared with the reference value Vdown just obtained, and if L act > V down, a deceleration instruction signal is output from the output port 20 of the control unit 15, and the driving transmission is 3 to the deceleration direction. L act > V down, not L
; If ict<V up, a speed increase instruction signal is output from the control unit 15, and the driving transmission 3 is switched to the speed increase direction.

Furthermore, if L act is not any of the above, the gear ratio is maintained as it is.

As described above, by automatically lowering the traveling speed when the load factor increases, and conversely by automatically increasing the traveling speed when the load factor decreases, changes in the engine speed are prevented and the load is increased. This allows the PT○ work to be performed at a constant speed. The idea of this invention can also be applied to droop control, but in the case of constant speed control, which attempts to keep the engine speed constant even when the load fluctuates, it is important to It is particularly effective in preventing deterioration.

In this invention, as described above, the traveling speed is changed according to an increase or decrease in the load factor, but in some cases, the increase in load is large and the constant speed control by the electronic governor 5 cannot be applied even if the vehicle speed is reduced. First, the engine speed may drop. Next, an example will be described in which a warning is issued in such a case.

Therefore, the overload determination load rate map as shown in Table 6 or the overload determination rack position map as shown in Table 7 is stored in the ROM.
19, and use this to detect overload,
It issues an alarm to the operator to prompt him to take measures such as lightening the load.

To explain the case of using Table 6, first, let's start with Figure 6 (
The actual load factor L act is determined by the procedure shown in a), and then the actual value Nact of the rotational speed at that time is applied to Table 6 to determine the load factor L over, which is the criterion, and then the load factor L over is determined as shown in Figure 8 (a).
Compare L act and L over as shown in
When act>Lover, the control unit 15 outputs an overload alarm=15- signal. Reference numeral 25 in FIG. 1 is an alarm means such as an indicator light or a buzzer which is activated by this signal.

In addition, in the control using Table 7, first the actual value Nact of the engine speed and the actual rack position Ract are recognized as shown in FIG. seek. And Ract and R
Rover is compared, and when Ract > Rover, an overload alarm signal is output and the alarm means 25 is activated.

Although the above embodiments are for a diesel engine, the control according to the present invention can be similarly implemented for, for example, a gasoline engine by making modifications according to the type of engine. In this case, the throttle opening corresponds to the rack position in the embodiment.

[C] Modified example of the embodiment In order to maximize the efficiency during work, it is necessary to utilize the maximum output point of the engine. It is not preferable from the point of view of efficiency that the torque characteristic is lower than the torque characteristic of . Moreover, when the speed change of the driving transmission 3 is stepped, the load changes stepwise as the vehicle speed changes, so depending on the load situation, it may not be possible to utilize the maximum output point at that engine speed. As a countermeasure against this problem, it is conceivable to set each zone so that the maximum output point is included in the appropriate zone Z2 as shown in FIG.

Therefore, in this modification, the driving transmission 3 is structured so that the gear ratio can be changed manually, and a means is provided to select whether to change the gear ratio automatically or manually. The number of rack positions has been increased to increase output.

The reason for excluding manual operation is to prevent the output up area from being intentionally used regularly.

Reference numeral 26 in FIG. 1 is an automatic/manual changeover switch of the traveling transmission 3, and the ROM 19 stores a maximum rack position map as shown in Table 8 below. Table 1, the number of maximum rack positions during manual operation, corresponds to Table 3 above, and corresponds to the original torque characteristics shown by the solid line in Figure 9, and the number of maximum rack positions during self-excitation. In Table (2), each rack position is increased, for example, by 10% compared to the rack position in Table I.

FIG. 10 shows the control procedure. First, the state of the automatic/manual changeover switch 26 is read, and depending on the result, the numerical table I
and numerical table ■ are selected.

Next, the actual value Nact of the engine speed is recognized, the corresponding maximum rack position Rmax (here R11, R2□, etc.) is calculated from a numerical table, and the target rack position Rset is calculated from the set value N5et of the engine speed and the actual value. be done.

Next, compare the maximum rack position and the target rack position,
If Rset > Rmax, the rack actuator 6 is driven so that the actual rack position Ract becomes Rset, and if Rset > Rmax, the rack actuator 6 is driven to correct Rset = Rmax.

In this way, when the automatic/manual selector switch 26 is set to the automatic side, the number table ■ whose rack position is higher than the manual number table 1 is selected, and the maximum output at that engine speed is selected. Even if the traveling transmission 3 is stepped, it is possible to operate using the maximum output point at that engine speed, resulting in efficient work. becomes possible.

In Table 9, a maximum rack position map called number table i is provided. This is because, in general, work styles are diverse and the required torque characteristics are different depending on the work, so multiple maps are provided to accommodate this (for example, Japanese Patent Laid-Open No. 59-192839 (see issue).

Therefore, the numerical table I is one of them, and a set of numerical tables for the manual maximum rack position and the automatic maximum rack position may be provided for each torque characteristic. In this case, a means for selecting a predetermined one from a plurality of sets of numerical tables is provided as appropriate, and a step of recognizing the selected set of numerical tables (i.e., torque characteristics) is inserted at the beginning of the procedure shown in FIG. Ru.

In addition, it is necessary to avoid driving for a long time in an output increase range that exceeds the limit, so if the load does not decrease after a certain period of time, it is necessary to stop the output increase operation and reduce the vehicle speed. It is desirable to add appropriate control procedures.

<Effects of the Invention> As is clear from the above description, the present invention detects the engine load based on the engine speed and fuel supply amount, adjusts the fuel supply amount according to the load, and adjusts the engine speed to a set value. In a work machine equipped with electrical control means that operates to maintain the
The gear ratio of the traveling transmission means is electrically controlled according to the load.

Therefore, the load can be detected without error, and the engine speed can be controlled with high precision to keep it constant.Furthermore, the vehicle speed can be changed appropriately according to the load, so it is not affected by changes in the load. It becomes possible to operate the engine at a constant speed, and it is possible to obtain a working machine that fully satisfies the requirement to perform PTO work at a constant speed even if the vehicle speed is sacrificed.

[Brief explanation of the drawing]

Figures 1 to 8 show one embodiment of the present invention.
The figure is a conceptual system diagram, Figures 2 to 4 are basic control flowcharts, Figure 5 is a characteristic diagram showing the relationship between engine speed, rack position, and shaft torque, and Figures 6 (a) and (b). and FIG. 7 are flowcharts of control according to the present invention, and FIG.
)(b) is a flowchart of control when an alarm occurs. FIG. 9 is a characteristic diagram showing the relationship between engine speed, rack position, and shaft torque in a modification of the embodiment, and FIG. 10 is a flowchart of control in the modification. FIG. 11 is an explanatory diagram of load detection in a conventional example. DESCRIPTION OF SYMBOLS 1... Work equipment, 2... Engine, 3... Travel transmission, 4... Fuel injection pump, 5... Electronic governor, 6...
・Rack actuator, 7・Rack position sensor, 8
... Rotation sensor, 9... Accelerator, 10... Accelerator position sensor, 13 Mode selection switch, 15...
・Control unit, 17...cpu, 19...ROM, 25
...Alarm means, 26...Auto/manual changeover switch. Patent applicant: Yanmar Diesel Co., Ltd. (and one other person) Agent: Patent attorney Shino 1) Actual figure 8 (
a) Fig. 8 (b) Stock interleave φyun (rpm)

Claims (1)

[Claims] (1) Electrical control that detects the engine load based on the engine speed and fuel supply amount, and adjusts the fuel supply amount according to the load to maintain the engine speed at a constant value set by the accelerator. In a work machine equipped with a means for driving, the transmission means for traveling can electrically control the transmission ratio, and the relationship between engine speed and output can be expressed in the form of multiple output characteristics depending on the size of the load. a storage means for storing; a characteristic selection means for specifying a region sandwiched between two adjacent output characteristics among the plurality of output characteristics; and a characteristic selection means for maintaining operation in the selected region at a set engine speed. A vehicle speed control device for a work machine, comprising: a speed ratio control means for changing a speed ratio of a traveling speed change means according to a detected actual load.