SE539265C2 - Work machine system and procedure for checking a work machine system - Google Patents

Abstract

A method of controlling a work machine system, the work machine comprising a power source (19), to power source coupled drive devices (20-24) for propelling the work machine, and a control system (28) controlling the operation. In the method changes in a functional quantity of the drive devices are monitored by means of a with control system connected sensor (34). The functional quantity monitored is such that the change of which predicts an increase in the load of the drive devices while driving over an obstacle. In addition, in the process, a change in magnitude is compensated by the control system by controlling the power source (19) or the drive devices (20-24), or both thereof, to drive over the obstacle. In the work machine system, the sensor (34) is adapted to monitor changes in said functional quantity, and the control system is - to compensate for changes in quantity - adapted to control the power source (19) or the drive devices (20-25), or both of them, to drive over the obstacle. (Fig. 3)

Description

FIELD OF THE INVENTION Field of the Invention The invention relates to a method for controlling a work machine system. The invention also relates to a work machine system. The invention also relates to a forestry machine.

BACKGROUND OF THE INVENTION Various work machines moving in the terrain run over impressions, pits, ditches, elevations, tufts, trunks of fallen trees, stones, stumps and similar obstacles. Driving over obstacles loads the drive devices of the work machine, since the drive devices must use more force than normal when driving over obstacles, and the force must also be available quickly so that the work machine does not stop or its speed would not be reduced unnecessarily. The reworking machine transports different loads, the power requirement is greater than normal and its variation is greater than normal.

Some work machines are forest machines, such as different harvesters, forwarders and combinations of these. To perform driving, the crown tip of a harvester is provided with a driving device, a so-called harvester head, with which an upright-growing tree trunk is cut, felled, pruned and sawn into parts of the desired size. The sawn tree trunks are collected together with a forwarder which is provided with a grab loader mounted on the crane and in whose cargo space the tree trunks are transported away.

A wheel-movable forwarder is presented in the publication EP-1923289-A2, comprising two chassis connected to one another by a joint, in which the drive devices are arranged. The rear chassis is equipped with a crane and a cargo space, in which the tree trunks gather. The front chassis is equipped with a driver's cab and a power source belonging to the drive devices, which is an internal combustion engine.

Driving over obstacles also causes the turning of work machines and can also have a negative impact on the stability of the work machine. The work machine's 2 drivers also experience the swing as unpleasant. The increased power demand and the variations in the power demand burden the drive devices more than normal, which can affect the need for their service and their service life.

Summary of the invention The method according to the invention for controlling a work machine system is presented in claim 1. The work machine system according to the invention is presented in claim 10. The forest machine according to the invention is presented in claim 15.

The method according to the solution is carried out or is applicable in a work machine system which comprises a power source, drive devices connected to the power source for propelling the work machine, i.e. for its movement, as well as a control system that controls the function.

As the work machine can be used different in the terrain moving work machines that are movable with wheels or caterpillar tracks or combinations of these.

The working machine is, for example, a forestry machine, such as a harvester for felling trees, a forwarder for transporting tree trunks, or a skimmer. The working machine can be an excavator or a forestry machine which uses the crane and chassis of an excavator and whose crane tip is equipped with a harvester head for handling trees or a felling head for felling trees. The working machine can be a tractor intended for agriculture and suitable for towing a forest trailer or to which a forest trailer has been connected for transporting tree trunks. A forest trailer is typically equipped with a crane and a grapple trunk attached to this for loading and unloading.

In the presented method, changes in a functional quantity of the drive devices are monitored with one or more sensors connected to the control system. The functional quantity monitored is one whose change predicts an increase in the load of the drive devices while driving over an obstacle. In the method, a change in the functional quantity is also compensated by controlling the power source or the drive devices or both of them by means of the control system to drive over an obstacle when the control system detects that the change in the functional quantity is greater than a predetermined limit value.

According to an example of the method, the drive devices are controlled by means of the control system so that the speed of the working machine decreases, in order to drive over an obstacle.

The work machine runs over the obstacle, and with the method described above, e.g. an increase in the pressure of the drive devices is damped or limited. A decrease in the speed reduces the power required to propel the machining machine, which directly affects the pressures of the hydraulic drive device or - in the case of a drive device based on any other technology - any other quantity, the change of which must be mitigated or limited.

The method avoids a reduction in the rotational speed of the power source, especially an internal combustion engine. A smaller change in the combustion engine rotation speed than before affects the fuel consumption, which decreases.

The consequence of this is also an improvement in driving comfort and an improvement in the stability of the work machine.

According to a second example of the system, the power source is also controlled by the control system so that the rotational speed at the power take-off of the power source increases at least instantaneously.

According to a third example of the system, the power source is also controlled by the control system so that the torque at the power take-off of the power source increases at least torque.

In one embodiment of the method, the drive devices are controlled by the control system so that their so-called Gear Ratio value changes to drive over an obstacle.

In a particular embodiment of the method, said functional quantity, the change of which is monitored to detect an increase in the load, is the hydraulic pressure of the drive devices. According to one example, the drive devices comprise a hydraulic pump and a hydraulic motor, and in the process said pump or motor or both of them are controlled by means of the control system so that the control is dependent on the change in said functional quantity.

The drive devices may comprise a hydraulic drive device, a mechanical drive device or an electric drive device, or a combination thereof.

The drive devices of the work machine can be based on different devices which convert generated or stored energy into kinetic energy for propelling the work machine. The power source can be e.g. an internal combustion engine and a mechanical shaft power generated by it, an accumulator system, a generator rotated by a single-combustion engine, or a fuel cell. In the case of energy transfer, the drive devices can use e.g. electrical energy, mechanical energy, hydraulic energy or pneumatic energy. For propulsion, work machines use e.g. hydraulic motors, compressed air motors, electric motors or mechanical devices.

According to a fourth example of the method, the control system also controls another device of the work machine system which consumes power from the power source. In this case, the function of the device is delayed or stopped at least instantaneous.

The advantage is a reduction in the load on the power source. The device can last.ex. a fan or an air conditioner.

A work machine system in which the solution is carried out or in which it is applicable comprises a power source, drive devices connected to the power source for propelling the work machine, and a control system which controls the function. In addition, the work machine system comprises one or more sensors which are connected to the control system. The sensor is adapted to monitor changes in a functional quantity of the drive devices, said functional quantity to be monitored being such, the change of which predicts an increase in the load of the drive devices while driving over an obstacle. To compensate for a single change in magnitude, the control system is also adapted to control the power source or drive devices, or both of them, for driving over an obstacle. According to one example, the control system is adapted to control the drive devices so that the speed of the working machine decreases for driving over an obstacle.

With a control system according to the solution, the benefit already presented above is achieved.

In a particular embodiment of the work machine system, said sensors are adapted to measure the hydraulic pressure in the drive devices.

According to one example, the drive devices comprise a hydraulic drive device, a mechanical drive device or an electric drive device, or a combination thereof.

The work machine system according to the presented solution is applicable in, for example, a work machine which is a forest machine moving in the terrain. According to a special example, it is a question of a forwarder moving in the terrain.

Brief description of the drawings In the following description, the invention will be further elaborated in detail by way of example and with reference to the accompanying drawings, in which Figure 1 shows a work machine which is a working machine moving in the terrain and to which the presented solutions can be applied, Figure 2 is a diagram showing drive devices of a working machine according to an example, which can be applied in the working machine of Figure 1, Figure 3 is a diagram showing drive devices of Figure 2 and couplings thereof hydraulic drive device in more detail, Figure 4 is a diagram showing couplings of drive devices according to a another example and its hydraulic drive device in more detail, and Figure 5 shows an example of the behavior of a functional quantity of the drive devices and the control of the drive devices. DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a working machine, in particular a working machine movable in the terrain, in which a solution according to that presented is applied. It is a single forest machine, which is more precisely a forwarder for transporting tree trunks. The forwarder comprises a front chassis 11 and a rear chassis 12, which are interconnected by a chassis track 13 and in which the drive devices are located. In the front chassis 11 there is a cab 14 and an energy source 15, and in the rear chassis 12 there is a crane 16 with a gripper 17 and a cargo space 18. The energy source is an internal combustion engine. Each chassis includes a rocking axle with 2 wheels, but in the front chassis you can alternatively use a standard axle with 1 wheel that is larger than the wheels in the rear chassis.

We will now examine drive devices of a work machine, which are based on an internal combustion engine as well as a combination of hydrostatic and mechanical drive device for moving the work machine. Said drive devices are edge applied in a forwarder according to figure 1.

According to Figure 2, the internal combustion engine at any given time generates a suitable power that is needed, for example, to move and drive the work machine in different situations and terrains. The mechanical power that the internal combustion engine 19 generates on its shaft is converted into a hydraulic power in a pump 20, the power being proportional to the feed pressure and the volume that the pump 20 produces. The pump 20 is adjustable, whereby the volume flow produced can be varied. The hydraulic power is utilized in a motor 21 which eats generates a driving torque and a rotational speed for a PTO shaft. The supply pressure produced by the pump 20 depends on the load and power demand of the pemotor 21. The rotational speed of the motor 21 depends on the volume flow produced by the pump 20 and the setting of the motor 21, if the motor 21 is adjustable. The motor 21 is again connected to a gear 22 (fast / slow), by means of which the mechanical power is transmitted to the wheels 27 of the work machine, for example by a cardan drive 23 and differential shafts 24 to rocking shafts with 2 wheels or to bogies 25 with work machines. The drive devices 27 are mounted on rotating wheel suspensions 26. The drive devices are controlled by the electronic control system 28 of the work machine, which also controls the internal combustion engine 19 through an electronic control unit 29 (ECU, 7Electronic Control Unit). The ECU (Engine Control Unit) is the engine control unit that controls and monitors engine functions.

The mechanical power generated by the internal combustion engine is proportional to the torque and rotational speed obtained from the internal combustion engine 1. The rotational speed or working speed of the work machine depends on a deflector determined control value typically given by a pedal 30. By means of sensor 31 the pedal generates a setting signal 32 position of the pedal 30 and which is fed into the control system 28. Other means, eg a control lever, can also be used to give the control value. It is typical that the greater the displacement in the position of the pedal or the control value, the higher the rotational speed or driving speed reached. Pressing the pedal 30, if necessary, also provides an opening of the working brake of the work machine, after which the control system 28 controls the pump 20 with a control signal which has a predetermined minimum level or a minimum value. The control signal is typically a current signal, on which the volume output produced by the pump 20 depends.

Figure 3 shows the drive devices of Figure 2 in more detail with respect to the hydraulic drive device. In this example, it is a question of a closed circuit and a single-circuit system, in particular a single-engine system. The function and numbering of different parts correspond to the numbering presented in Figure 2 and the description relating to it.

The pump 20 is, for example, an axial piston pump which can be adjusted in its stroke volume (Vg) with an inclined disc, in which the direction of the volume and thereby the direction of rotation of the further motor and the working direction of the working machine can be changed by turning the inclined disc of the pump on both sides of the neutral intermediate position. The controllable quantities are the pump's stroke volume and at the same time the volume flow produced by the pump. The motor 21 is, for example, an axial piston motor with an inclined disc or an inclined shaft, or a radial piston motor. One-adjustable motor includes e.g. a rotatable bevel. The controllable parameters are thus the engine stroke volume (Vg) and rotational speed. The motor 21 can also have a fixed, ie. constant stroke volume (Vg). The controllable quantity is the rotational speed of the motor.

Figure 4 shows the drive devices of Figure 2 in more detail with respect to the hydraulic drive device. In this example, it is an open circuit. The function and numbering of different parts correspond to the numbering presented in Figure 2 and the description relating to it.

By means of a hydraulically operating drive device in Figure 4, an adjustable driving speed for the working machine is achieved, since the volume flow to the motor 21 is developed with a valve 35 adjustable volume flow. Preferably, it is a one-way valve that is electrically controllable and proportionally functioning. The volume fl fate of the valve depends on the position and opening of the valve, which in turn are controlled by a control signal. The control signal is typically a current signal, on which the volume fl fate of the valve depends. In Figure 4, the valve 35 is shown in a principle diagram, but said valve and its functions can also be performed by means of one or more different hydraulic components which are interconnected with channels.

In the example of Figure 4, the pump 20 is adjustable with respect to stroke volume (Vg), e.g. an axial piston pump. The controllable quantities are the stroke volume of the pump and the volume flow produced by the pump. The motor 21 has a fixed, i.e. constant stroke volume (Vg); it is e.g. an axial piston engine or a radial piston engine. The controllable quantity is thus the rotational speed of the motor.

The work machine's control system monitors the drive devices, e.g. the drive device, its hydraulic control circuit and all associated auxiliary functions. Said control system works e.g. in a PC operating environment. The control system equipment is located within the reach of the driver in the cab. Regarding the connection to actuators, the control system control automation is based on a CAN bus solution according to the prior art, where information is transmitted in digital form.

According to one example, the control system equipment comprises a display module, a PC keyboard, a mouse pad, a central unit (HPCCPU) with processor and memory, and in many cases also a printer, and the control system modules. The equipment also includes one or more control panels, whose keys, pushbuttons and joysticks are used to influence the control system. In this example, the control system 28 has been connected or belongs to its equipment at least one sensor (eg sensor 34 according to Figure 3 or Figure 4) or a measuring device which gives a signal which is proportional to the value of a functional quantity of the working machine. 9Preferently, said sensors are also connected e.g. to a drive device of the machining machine.

In the examples of Figures 3 and 4, the sensor 34 is connected to the hydraulic drive device of the work machine. The control system 28 comprises e.g. a predetermined parameter, the value of which depends on the magnitude measured by the sensor 34. Saw magnitude can be measured continuously at a requested sampling frequency or bar periodically. Said quantity is, for example, pressure, in particular the pressure of the hydraulic drive device, for example the supply pressure generated by the pump 20, or the pressure in the motor 21.

According to a second example, said quantity is the rotational speed of the internal combustion engine, in particular the rotational speed of its PTO shaft. According to a third example, said quantity is the internal pressure of the wheel 27 which is measured by a sensor.

The application required for the execution of the presented solution and the software contained therein are installed in the processor-based central unit of the control system, which comprises the necessary RAM and mass memories. The control system uses an operating system, during which the application is run. The device and the operating system comprise the necessary applications and protocol means for communication with other devices.

The work machine's control system is based on e.g. CAN bus technology (ControlArea Network) and decentralized control. The system consists of independent intelligent modules that communicate via a CAN bus. The control system controls the power source, the drive device and with these connected auxiliary functions, and if necessary also the crane system. The system typically consists of modules in the CAN bus. The control system or one of its modules takes care of the control of the power source, the drive device and the auxiliary functions and communication associated therewith, and controls the stroke volume of said pump and motor.

The following is an example, in which the functional load of the working machine is to be considered, the value of which depends on the load of the drive devices. The load depends on the generated power needed to move and drive the working machine in different situations and terrains. In particular, it is a question of such a change in the value of the quantity which is a consequence of the work machine running over an obstacle or starting to run over an obstacle. The current change in the value of the quantity represents a future increase in the load; in other words, it predicts a coming major change. By monitoring said magnitude, one can thus predict the coming load. In this way, the control system can prepare for changes in the load and control the drive devices in a requested manner in said situation.

In Figure 5, the quantity to be monitored is the pressure of the hydraulic drive device. Figure 5 shows the behavior of the hydraulic drive device pressure within a certain period of time. According to one example, it is a question of the pressure measured by a pressure sensor, for example the pressure 36 measured by the sensor 34.

In a similar manner as the pressure 36, some other functional quantity of said work machine can also behave, so that what is to be presented in the following can also be applied to other quantities in addition to the pressure.

At an obstacle or when hitting an obstacle, the value of the quantity changes, since e.g. a greater force is required to ascend the obstacle or to maintain a required driving speed despite the obstacle. In the case of a hydraulic drive device, the supply pressure of the pump 20 or the pressure of the motor 21 increases (Figure 3 or Figure 4). In the example of Figure 5, an increase in the pressure 36 can be seen, which is higher than a set limit value 38.

The control system detects the change in magnitude and preferably also compares the change in magnitude with a predetermined limit value. If the change in magnitude is greater than the said limit value, the control system changes to a state in which it affects the working machine to compensate for the change that has occurred. As for the change in size, e.g. the absolute or relative change or rate of change. In addition, it is often the case that the change in magnitude must occur within a set time interval. In the example of Figure 5, the increase in pressure must be at least about 60-100 bar or preferably at least about 75 bar. The change in pressure must occur within a time interval of no more than approx. 80-150 ms or preferably within a time distance of at most 120 ms.

The control system controls the drive devices with a control signal which depends on the requested driving speed. When it comes to e.g. a hydraulic drive device, controls said control signal b | .a. a pump. Said control signal is dependent on b | .a. a setting signal (eg setting signal 32 according to Figure 3 or Figure 4) and according to an example also the maximum value of the rotational speed of the internal combustion engine, or the current rotational speed of the internal combustion engine, or the rotational speed of the internal combustion engine corresponding to the setting signal, or a combination thereof. The control signal used by the control system is, for example, a control signal which changes the so-called Gear Ratio value of the hydraulic drive device, or alternatively the control signal affects such quantities of the drive devices in which a change causes a change in the Gear Ratio value. The control system utilization tabulation, rules or calculation algorithms in the control. The control system also includes adjustable parameters, in which values of variables as mentioned in this description have been stored. Preferably, they can be set to the user, in order to be able to influence the system's function.

In the case of a hydraulic drive, the Gear Ratio value refers to the characteristics of either the pump or the motor, e.g. the position of the inclined disc, or the relationship between the characteristics of the pump and the motor, e.g. the relationship between the position (angle) of their inclined discs. The drive device can be realized completely mechanically, e.g. with a gearbox, whereby the Gear Ratio value can be determined between its power intake and power take-off.

In the case of driving over an obstacle and an increasing need for power, the control system compensates the situation so that the driving speed is reduced or the working machine is braked, the control system affecting either power source or other drive devices, or both. According to one example, the reduction of the exit speed is approx. 10-35% depending on the level of the current driving speed. In the example of Figure 5, the control system affects the current driving speed (eg 1.5-4.0 km / h) so that the Gear Ratio value 37 of the hydraulic drive device is immediately reduced, allowing a delay of e.g. 50-120 ms. The reduction is approx. 10-35% depending on the current level of the Gear Ratio value. Alternatively or in addition, the reduction may also depend on the current driving speed. Preferably, the higher the driving speed, the greater the decrease. Alternatively, the Gear Ratio value 12 is reduced to a predetermined value. In this example, the driving speed is affected by turning the engine 21 oblique disc so that the stroke volume decreases.

The Gear Ratio value of a mechanical drive device can also be affected, in the case of stepless or discrete Gear Ratio values in particular gearboxes or transmissions, as in e.g. a planetary gear. This is, for example, the relationship between the rotational speed of the drive device power intake and the rotational speed of its power take-off, or a correspondingly determined relationship between the functional loads of the power take-off and the socket.

According to an example, the control system compensates the situation at the same time by increasing the rotational speed of the power source, whereby the control system affects the power source by e.g. an electronic control unit (ECU). The control system controls the electronic control unit, as well as the power transmission, by means of one or more control signals. The rotation speed is kept at an elevated level for e.g. a predetermined delay. The amount of increase in rotational speed is e.g. predetermined or depending on e.g. the current rotational speed.

The control system compensates for the situation of e.g. a predetermined delay.

In the example of Figure 5, the Gear Ratio value is kept reduced for the time being by a delay 39 (eg 300 ms), after which the intention is to restore the Gear Ratio value to the value it had before the compensation was started, or to a value substantially corresponds to this, or to a value corresponding to the current state of said setting signal.

The control system ends the compensation by resetting the driving speed which the working machine had before the compensation started, or to a driving speed which substantially corresponds to this, or to a driving speed which corresponds to the current state of said setting signal. The control system affects either the power source or other drive devices, or both. The reset preferably takes place by a stepwise increase of the travel speed, whereby the change of the travel speed per a certain unit of time is limited, or the rate of change of the travel speed is limited. In this case, the control system can apply various ramp functions, according to which the necessary control signals are generated. Such a ramp function can also be seen in Figure 5, in which the Gear Ratio value is increased after the delay 39. The Gear Ratio value is gradually increased so that the change of the Gear Ratio value per a certain unit of time is limited.

If a new change that requires compensatory measures is discovered in the quantity that is monitored, it works again as presented above. If necessary, the said ramp function is interrupted.

The work machine runs over the obstacle, and with the method described above, e.g. an increase in pressure 36 is attenuated or limited.

A situation has been described above in particular, in which an increase in the need for force caused by driving over an obstacle is foreseen. The increase in the need for power can also be a consequence of other situations, but one can react to this with the method and system presented above.

Claims (15)

1.: _ Method for checking a work machine system, which work machine system comprises a power source (19), drive devices (20-24) connected to the power source, pre-propulsion of the work machine, and a control system (28) which controls the function, characterized in that in the method: in a functional quantity of the drive devices is monitored by means of a sensor (34) connected to the control system, the functional load quantity being monitored is such that its change predicts an increase in the load of the drive devices while driving over an obstacle, and - a change in the functional the quantity is compensated by means of the control system by controlling the power source (19) or the drive devices (20-24), or both of them, to drive over the obstacle, when the control system detects that the change in the functional quantity is greater than a predetermined limit value. Method according to claim 1, characterized in that said compensation is performed in particular when a) the control system detects that the rate of change of the functional quantity is greater than a predetermined limit value, or when b) the control system detects that the absolute or relative change in the functional quantity within a predetermined time distance is greater than a predetermined limit value. Method according to claim 1 or 2, characterized in that in the method the drive devices (20-24) are controlled by the control system (28) so that the speed of the working machine decreases, in order to drive over the obstacle. Method according to Claim 3, characterized in that the power source (19) is also controlled by the control system (28) so that the rotational speed of the power take-off of the power source increases at least momentarily. Method according to one of Claims 1 to 4, characterized in that the power source (19) is also controlled by the control system (28) so that the torque of the power source power take-off increases at least momentarily. Method according to one of Claims 1 to 5, characterized in that the drive devices (20-24) are controlled by the control system (28) so that their gear ratio (Gear Ratio value) is changed, in order to drive over the obstacle. Method according to one of Claims 1 to 6, characterized in that also another device of the work machine system, which consumes power from the power source, is controlled by the control system (28) so that the function of the device is at least momentarily delayed or its function is stopped at least momentarily. Method according to any one of claims 1-7, characterized in that the drive devices comprise a hydraulic pump (20) and a hydraulic motor (21), and in the method said pump (20) or said motor (21) or both of them are controlled co-control system, depending on the change in said functional quantity. Method according to one of Claims 1 to 8, characterized in that said functional quantity is the hydraulic pressure in the drive devices. 10. Work machine system, comprising: 11 - a power source (19), - the drive device working machine connected to the power source, and - a control system (28) which controls the function, characterized in that the work machine system further comprises: - a sensor (34) connected to the control system and adapted to monitor changes in a functional quantity of the drive devices, the functional quantity to be monitored being such that its change predicts an increase in the load of the drive devices while driving over an obstacle, and - the control system is adapted to control a change in the functional quantity to control the power source (19) or the drive devices (20-25), or both thereof, for driving over the obstacle, when the control system detects that the change in the functional quantity is greater than a predetermined limit value. (20-25) for propulsion of. Work machine system according to claim 10, characterized in that the work machine system is arranged to perform said compensation especially when a) the control system detects that the rate of change of the functional quantity is greater than a predetermined limit value, or when b) the absolute or relative change in functional quantity detected by the control system within a predetermined time distance is greater than a predetermined limit value. Work machine system according to claim 10 or 11, characterized in that the control system (28) is adapted to control the drive devices (20-24) so that the speed of the work machine decreases, in order to drive over the obstacle. Work machine system according to claim 10, 11 or 12, characterized in that the saw sensor (35) is adapted to measure the hydraulic pressure in the drive devices. Work machine system according to one of Claims 10 to 13, characterized in that the work machine is a forest machine movable in the terrain. Forest machine, in particular a forwarder movable in the terrain, characterized in that it comprises a work machine system according to claim 10.