DEVICE FOR SPEED SETTING OF AN INTERNAL COMBUSTION ENGINE, PARTICULARLY DIESEL ENGINE, IN EARTH WORKERS

Abstract: A device for setting the speed of, in particular, an excavator engine which is to operate at a speed adapted to the type of work to be done and is automatically shifted to resting speed when no work is done. In this manner, fuel consumption and the disturbing effect of unnecessarily high noise levels are reduced. The setting device comprises simple electronic control units and actuates the fuel-controlling means (7) of the engine in that a d.c. servo motor (1) connected to said fuel-controlling means is supplied with a referene value signal corresponding to the desired engine speed. By manual activation of a push-button (16) on the control lever, the device provides the possibility of manually stepping the engine speed upwards or downwards to at least three different levels (w1, w2, w3). The device also comprises a resting speed unit (3) ("idling unit") having a preset high (z1) and preset low (z2) resting speed. If the manual control means of the machine are not activated for a given short period of time, the unit (3) provides a high (z1) resting speed, and if no manual control means is activated for a further period of time, it provides a low (z2) resting speed. On activation of any manual control means, the engine resumes the actual working speed.

Description: DEVICE FOR SPEED SETTING OF AN INTERNAL COMBUSTION ENGINE, PARTICULARLY DIESEL ENGINE, IN EARTH WORKERS. The present invention relates to a speed setting device of the type stated in the preamble of Claim 1. A diesel engine normally has a regulator for controlling, via a lever on the fuel injection pump, the amount of fuel supplied to the combustion chamber of the engine, to drive the engine at a predetermined speed. In an excavator, the engine usually is placed in the rear part of the rotatable machine superstructure, and the above-mentioned speed control can be actuated manually and variably from the driver's seat by means of a hand-wheel, as well as by steps by means of a push¬ button on the control lever, said hand-wheel and said push-button being adapted/ via a -electromechanical control system, to transmit the movement to the lever on the fuel injection pump. During the excavating work, the engine shall operate at a speed suitable for the type of work. Before or during excavation, the operator can set, for instance by means of a hand-v/heel, an initial speed which, together with the speed control device, provides an operating speed suitable for the work. As soon as the operator actuates his controls to carry out excavation, the engine speed is increased automatically from resting speed to working speed. If required, the device permits manual stepwise increase/decrease of the engine speed during work, and automatic return to resting speed when no work is carried out. A prior art device for the above-mentioned speed control, Swedish patent 394403 comprises a hydro- mechanical control means connected to the operating system of the work unit of the machine, said system actuating the lever of the fuel injection pump. In this arrangement, the automatic engine control varies between a variably settable resting speed and the racing speed. This arrangement was intended to reduce automatically the engine speed when no excavating movement takes place, and to increase the motor speed when excavation is carried out. In this manner, fuel consumption is reduced and, at the same time, also the high noise level period. Other automatic idling systems in excavators utilise, in principle, a pneumatic cylinder, the piston rod of which is connected to the lever on the fuel injection pump of the engine. The cylinder is activated by means of a pressure control device in the hydraulic circuit, or by an electric switch on the control lever. These means provide for automatic control only between a resting speed/idling speed and a maximum speed. The present invention affords completely different speed setting possibilities well suited to make excavation work more effective and to further minimise fuel con¬ sumption and to reduce the noise level. In"addition, its electromechanical unit has but few moving parts and ma be readily adapted to different speed control patterns. The speed setting possibilities are realised by means of the arrangement s defined in the charac¬ terising clause of the appended claims. The invention will be described in more detail below, reference being had to the accompanying drawings illustrating an embodiment. Fig. 1 provides, in the form of a block diagram, a basic functional description of the device, while Fig. 2 describes the function in mere detail. The manner in which the speed is varied y means of different factors is illustrated in Figs. 3 and 4. Fig. 5 shows possible engine speed settinσs . The speed setting device according to the invention, which has been designed for internal combustion er.αines , especially diesel engines, in earth-working machines, comprises a system which is actuated in a specific manner and sets the diesel engine speed by means of a d.c. servo motor, the output shaft of which is fixedly connected to the control lever of the fuel injection pump of the diesel . engine. A basic functional description of the system is given in Fig. 1. The system, and thus the speed of the diesel engine, is actuated by the manual control means 14 (levers, pedals etc) of the machine, a push-button 16 on the control lever, and means 9 for manual setting of the engine speed. For changing to fixedly set resting speeds, when no excavating movement is carried out during machine operation, a so-called fuelmiser unit 3 is provided. The fuelmiser unit 3 can be manually connected or dis- connected by means of a special switch 8. When the fuel¬ miser unit is disconnected, the diesel engine speed corresponds directly to the output signals from the speed determination unit 4 (i. e. the reference value corresponds to the actual working speed). The output diesel engine speed is indicated by a speed indicator 11. If required, the speed of the diesel engine 14 can be quickly changed manually by means of the push-button 16 on the control " lever. The speed setting signals which determine the actual value to the d.c. servo motor 1 and which thus control the engine speed, are as follows: - Accelerator setting (for instance a potentio¬ meter on the instrument panel ) . - Push-button on right-hand control lever - Diesel engine speed - Activated or unactivated levers/panels. Fig. 2 illustrates in more detail the function of the speed setting device for the diesel engine of the excavating machine. The device comprises a d.c. motor unit 1, a regulator unit 2, a fuelmiser unit 3 with a control unit β y a speed determination unit 4 comprising a control unit ESC 5 (Engine Speed Control) and a signal transducer 15. The d.c. motor unit 1 which has an output shaft including a gear and a transducer showing the rotation of the motor unit output shaft, is fixedly connected to the control lever 7 of the fuel injection pump of the diesel engine, said pump controlling the engine speed. The d.c. motor unit 1 sets the control lever 7 for engine speed control by means of the regulator unit 2, the input signal y (reference value) of which 5 is determined by the speed determination unit 4 and the fuelmiser unit 3. The feedback value x of the regulator unit 2 corresponds to the angle of rotation of the output shaft of the d.c. motor unit 1. The feedback value x is indicated by, for example, a rotary 10 potentiometer of linear characteristic. To prevent over- speeding of the diesel engine when full speed (so-called racing speed) is set, there is provided an adjustable fixed stop which the lever 7 strikes in the event of a movement greater than the angular deflection of full- 15 load speed. The output signal u (input signal to the fuelmiser unit 3) of the speed determination unit 4 preferably corresponds to the determined actual working speed of the diesel engine. The input signals of the speed determination unit 4 are an input signal from 20 the manual accelerator 10 and from the speed indicator 11 of the diesel engine, and a constant input signal from the setting means 9. The actual engine speed (low, variable or high) is indicated on, for example, a display in the driver's 25. cabin. By means of the control unit 5, ESC (Engine Speed Control ) , the output signal u corresponding to the actual working speed may be obtained for three predetermined working speeds. One of these working speeds, the variable 30 working speed w_ , is manually and variably settable from the driver's seat. The variable working speed is determined by, for example, the hand-wheel for setting the accelerator 10 on the instrument panel. A complete clockwise turn of the handv/heel gives a diesel engine 35 working speed corresponding to full-load engine speed (so-called racing speed), and a complete counter-clock¬ wise turn of the hand-wheel qives the lowest enσine working speed (idling speed). Furthermore, manual changing of the actual working speed to the nearest higher/lower working speed (for example w^ to w-,, or w~ to w, ) can be effected by means of, for example, a push-button 16 in the right-hand control lever. The output signal of the speed determination unit 4 corresponds to three possible actual working speeds: 1. Low working speed 2. Variable working speed 3. High working speed. The low working speed (corresponding to the signal w, ) is obtained by direct signal conversion in the signal transducer 15 of the variable speed (corresponding to the signal w_ ) settable from the driver's seat. The high working speed (corresponding to signal w is obtained by means of the setting means 9 (for example a potentiometer) which is set to a value corresponding to the racing speed of the diesel engine. The control unit 5, ESC (Engine Speed Control) of the speed determination unit 4 changes the actual working speed if, due to actuation of the manually set- table accelerator 10, the variable working speed exceeds a predetermined value of the low working speed (for example about 900 rpm), in the manner described below for the embodiment also illustrated in Fig. 3. 1. Changing the actual working speed to the next higher possible speed (from low to variable working speed, or from variable to high working speed) occurs when the push-button 16 on the right-hand lever has been activated for at most 0.4 second. 2. Changing the actual working speed to the next lower possible speed (from high to variable working speed, or from variable to low working speed) occurs when the push-button 16 on the right-hand control lever has been activated for more than 0.4 second. 3. Changing of the actual working speed to the variable speed occurs when the variable working speed falls below the low resting speed (about 900 rpm), or when the actual speed of the 5 combustion engine falls below about 300 rpm. The actual reference value for setting the diesel engine speed is finally determined by the fuelmiser unit 3, the input signals of which are obtained, besides from the speed determination unit 4 (signal u), from _0 transducers in the manual control means 14 of the working machine, the engine speed indicator 11 and the fuelmiser switch 8. In operation, the fuelmiser unit can be con¬ nected or disconnected by the switch 8. This implies that, when the fuelmiser unit is disconnected, its input 5 and output signals merely consist of the output signal u of the speed determination unit 4, i. e. the fuel¬ miser unit does not, in the disconnected position, actuate the engine speed (the reference value corresponds to the actual working speed). 20 The fuelmiser unit 3 is used for reducing the combustion engine speed from the actual working speed to the preset fixed resting speed, when the machine is not working, and for increasing the speed when the machine is working. The output signal y (the reference 25 value of the regulator unit 2 ) of the fuelmiser unit 3 is then provided, by the control unit 6, with a signal corresponding to three alternative speed possibilities: 1. Low resting speed 2. High resting speed 30 3. Actual working speed The low and high resting speeds are set at suitable constant values by the setting means 13 and 12. The fuelmiser unit is inactive, i. e. its output signal corresponds directly to the output signal of 35 the speed regulation unit 4 (i. e. the reference value corresponds to the actual working speed) when - the fuelmiser switch 8 on the instrument panel is in the "off" position; - the diesel engine speed is below 300 rpm; - the parking brake of a wheeled excavator is not in the excavating position. When the fuelmiser is disconnected, the reference value y corresponds to the actual working speed (signal u). hen the fuelmiser is connected and active, the reference value speed is changed in the manner indicated below and shown in Fig. 4. 1. Changing of the reference value speed from the resting speed (low or high) to the actual working speed occurs when any control lever (for control¬ ling boom, bucket, dipper arm, slew, and bull- dozer blade movement) or pedal (for caterpillar movement forward/backward, or additional equipment) is activated by a movement greater than the dead band, i. e. a signal from lever/pedal movement greater than a given predetermined value. 2. Changing of the reference value speed from the actual working speed to high resting speed occurs when no lever or pedal has been activated for, for example, 1 second. 3. Changing of the reference value speed from -high to low resting speed occurs when no lever or pedal has been activated for, for example, another 3 seconds . Fig. 5 illustrates the different speed setting possibilities available. It should be noted that the fixed speeds (low/high resting speed and low/high working speed) preset for the automatic speed setting are placed in an order and a dimension such that the speed setting can be effected in the most convenient manner by means of tie above-mentioned automatic setting possibilities. It appears from Fig. 4 that speed setting in the present case may occur either manually or automatically, and that the automatic setting may occur between a settable lower speed which is higher than (for instance 300) the idling speed and an upper engine speed limited by the racing speed. Although the invention has been described above in its electrical application, it is, of course, possible to replace the means referred to at least partly by pneumatic or hydraulic means.

Claims: 0439 CLAIMS 1. A device for setting the speed of an engine (M) in a working machine, especially an excavator, comprising a manually adjustable control device (3, 4) adapted to provide electric signals (y) which are applied to a driving device (1, 2) connected to the fuel regulator (7) of the engine (M) , c h a r a c ¬ t e r i s e d in that said control device (3, 4) comprises a unit (3) for setting the resting speed of the engine (M), and a unit (4) for setting the working speed of the engine (M), and means for automatically shifting from the actual speed to working speed or the resting speed, when the machine makes no working move¬ ments . 2. A device as claimed in claim 1, c h a r a c - t e r i s e d in that said unit (3) for setting the resting speed has at least two manually operable resting speed setting means (12, 13) and a shifting device (6) which, for shifting purposes, is operable by the manual control means of the working machine, a manually re- leasable signal, or a change in the hydraulic pressure and/or the speed of the engine (M), said shifting device having an output connected to said driving device (1, 2 ) and inputs connected to said resting speed setting means (12, 13) and to the unit (4) for setting the working speed of the engine (M), in order to connect to said driving device ( 1 , 2 ) either one of said setting means (12, 13) or said unit (4) for setting the working speed. 3. A device as claimed in claim 2, c h a r a c ¬ t e r i s e d in that said unit ( 4 ) for setting the working speed has a control means (ESC) having an output connected to one input of the shifting device (6), and at least two inputs connectible to said output, one of said inputs being connected to a manually settable means (10) providing an output signal (w~) for a first working speed, said other input being connected to a means (9) providing a prefixable output signal (w„) for a second working speed. 4. A device as claimed in claim 3, c h a r a c - t e r i s e d in that said control means (ESC) has a third input connectible to said output and connected to a signal transducer (15) connected to said manually settable means (10) and providing an output signal (w, ) for a third working speed. 5. A device as claimed in claim 4, c h a r a c ¬ t e r i s e d in that said control means (ESC) is con¬ nected, for connection of a desired input to said output, to a manually operable switch, preferably an incremental push-button (16) mounted in a control lever. 6. A device as claimed in claim 4, c h a r a c ¬ t e r i s e d in that said control means (ΞSC) is adapted to sense the actual speed of the engine (M) to prevent shifting between the working speeds (w, , w„ , w_ ) when the speed of the enging (M) falls below a predetermined minimum speed and to automatically connect the input connected to said manually settable means (10) to its output.

Inventors: TORDENMALM LARS OESTEN, TORDENMALM, LARS, OESTEN
Applicants: AKERMANS VERKSTAD AB, AOKERMANS VERKSTAD AB
Application year: 1985
Main classification: F02D1
IPC codes: F02B3, F02D41