SE1351436A1 - Procedure and control arrangements for controlling the transmission of power of a vehicle, as well as work machine - Google Patents

Abstract

The invention relates to a method for controlling propulsion transmission of a vehicle, in which method the inclination of the surface (28), along which the vehicle (10) is driven, is determined, and in which method the propulsion transmission and the brake (12) are controlled according to the determined inclination of the surface (28) and / or weight (Gtk) of the vehicle (10). In the method according to the invention, when the vehicle (10) is set in motion along an inclined surface (28), the brake (12) of the vehicle (10) is disengaged after a time delay (WORK_BRAKE_RELEASE_DELAY) from the clutch of the propulsion transmission. The length of the time delay (WORK_BRAKE_RELEASE_DELAY) is adjusted depending on the inclination of the surface (28) and / or the weight (Gtk) of the vehicle (10). The invention also relates to a control arrangement according to the method according to the invention, and to a working machine with a control arrangement according to the method according to the invention. Fig. 2

Description

2 hill), which is produced by gravity and is dependent on the weight of the work machine and the steepness of the ascent, does not exceed the gripping force produced by the brakes and the drive transmission together at any stage of start on a slope with a downhill slope. In other words, the principle of the auxiliary system when starting uphill is that when the vehicle is set in motion uphill, the force holding the vehicle still is transmitted from the brakes to the power transmission without weakening in between, whereby the vehicle can be set in motion in a smooth manner without jerks. Such a now known auxiliary system at start in opposite slope has been described in e.g. publication US 2010/0168974 A1. This auxiliary system when starting on an uphill slope keeps the brakes of the work machine engaged until the drive transmission has had time to be switched on, whereby the work machine no longer moves downhill until it moves in the intended direction of travel.

In the now known auxiliary systems when starting uphill, the torque produced by the brakes is usually adjusted according to how the operator of the machine presses the accelerator pedal uphill, when the machine is set in motion uphill. Then you have to apply the braking force according to the position of the accelerator pedal, i.e. estimate what force the brakes must at least provide so that the work machine would not move downwards first. This is challenging if you do not know the steepness of the hill and the weight of the work machine precisely enough. In addition - although this information is often also available in modern systems - it must be possible to determine the torques on the wheels precisely enough so that the power transmission is not unnecessarily loaded by the brakes preventing the wheels from rotating too much.

Brief Summary of the Invention The object of the invention is to provide a new method by which the vehicle's power transmission and braking force can be controlled in a situation of starting in the opposite direction so that the wheels of the process-controlled vehicle do not lose grip on the ground, especially when the vehicle sets moving uphill, and at the same time - in a simpler and safer way than before - ensures that the vehicle's power transmission is not overloaded despite the fact that rearward rolling is prevented by the brakes. The object of the invention is also to present a control arrangement which functions according to the method according to the invention, as well as a working machine with a control arrangement which functions according to the method according to the invention.

The invention is based on the property of the propulsion transmission that the attainment of the propulsion which keeps the vehicle still and moves it forward after the start of driving operation takes the propulsion transmission the longer, the steeper the slope (ie more inclined surface) along which the vehicle is to move and the heavier the vehicle is . Thus, by delaying the time when the brake holding the vehicle stationary is disengaged, with a time delay whose length depends on the inclination of the surface and the weight of the vehicle, one can prevent the vehicle from moving downhill without precisely adjusting the braking force generated by the brake and the driving force generated by the propulsion transmission at the time when the vehicle sets in motion. Expressed in a more precise manner, the method according to the invention is characterized by what is presented in independent claim 1. The control arrangement according to the invention, on the other hand, is characterized by what is presented in claim 8, and the working machine by what is presented in claim 13. The dependent claims 2- 7, 9-12 and 14-15 present some advantageous embodiments of the method, the control arrangement and the working machine according to the invention.

The advantage of the method, steering arrangement and working machine according to the invention is that due to the adjustment of the length of the time delay the braking force and the force generated by the drive transmission (ie thus the torques affecting the vehicle wheels in general) do not need to be adjusted relative to each other. In other words, the method and steering arrangement according to the invention can prevent rolling of the vehicle down the hill before switching on the propulsion transmission, without risk of overloading the propulsion transmission (due to the stopping with the brake) in a technically simpler way than before. A further advantage of the method and the control arrangement according to the invention is that the same system can be applied independently of the operating principle of the drive power transmission, when it is investigated for this purpose. the power transmission method appropriate dependence between the length of the time delay and the slope of the surface.

It should be noted that the term "surface slope" is often used in the description of this invention. In the description of this invention, it means the inclination of the surface on which the vehicle stands still or moves.

Thus, the slope of the surface can mean the slope of a surface formed by e.g. a 4 terrain outside the road network or a structure (eg a road, a floor, a ramp, a bridge, or the like) built on the ground.

According to a first aspect of the method according to the invention, the weight of the vehicle is determined on the basis of it, whether the vehicle has a load and how heavy this load is.

According to a second aspect of the method according to the invention, the weight of the vehicle is determined by means of a weight measuring instrument in the vehicle.

According to a third aspect of the method according to the invention, the time delay begins when the transmission ratio of the power transmission of the vehicle is greater than zero.

According to a fourth aspect of the method according to the invention, the time delay below a certain predetermined limit value increases linearly as a function of the slope of the surface.

According to a fifth aspect of the method according to the invention, the rate of increase of the time delay is adjusted according to the weight of the vehicle.

According to a sixth aspect of the method according to the invention, the time delay is kept constant after a certain limit value.

According to a first aspect of the steering arrangement according to the invention, the steering system of the vehicle comprises a programmable controller, and the means for delaying the brake is a program stored in the programmable controller.

According to a second aspect of the steering arrangement according to the invention, the measuring devices comprise at least one inclination sensor which is arranged to measure the position of at least a part of the vehicle relative to the horizontal plane for determining the inclination of the surface.

According to a third aspect of the steering arrangement according to the invention, the steering arrangement comprises a means for determining the direction of travel for determining whether the vehicle is to move up or down the inclined surface.

According to a fourth aspect of the steering arrangement according to the invention, the steering arrangement comprises a weight determination instrument for determining the weight of the vehicle.

According to a first aspect of the working machine according to the invention, the working machine is a hydraulic and / or electric working machine.

According to a second aspect of the work machine according to the invention, the work machine is a Forestry Machine.

Description of the drawings In the following the invention will be described in more detail with reference to the accompanying drawings, in which figure 1 shows a forest machine which is provided with a control arrangement for propulsion transmission according to the invention, when it is on an inclined surface, figure 2 shows a hydraulic circuit diagram for the work brake of the forestry machine shown in Figure 1, and Figure 3 is a diagram showing the relationship between the time delay between switching on the drive transmission and disengaging the working brake of the forestry machine shown in the preceding figures, and the slope of the surface.

Description of the Embodiments of the Invention in Detail Figure 1 shows a forestry machine 10 which in this case is a forwarder. As shown in Figure 2, the forwarder 10 comprises a working brake 12 and a hydraulic drive transmission, which are controlled by a method according to the invention, i.e. so that there is a time delay between the time when the working brake 12 is released and the time when the drive transmission is switched on, such that when setting in motion on an inclined surface 28 (ie on a slope) as shown in Figure 1 so that the direction of travel is up the hill, the work brake is only released after this time delay. The time delay starts from the time when the drive transmission is switched on, i.e. when the machine operator presses the accelerator pedal 22 for the drive motor 24 located in the cab 24. With this action the operator increases - in the case of hydraulic power transmission - revolutions of the drive motor 26 rotating a hydraulic pump. wherein the control system of the forwarder 10 controls the pressure medium produced by the hydraulic pump to the hydraulic motor which rotates the wheels. The forwarder 10 according to figure 1 could also be equipped with an electric drive power transmission. In that case, pressing the accelerator pedal would mean that an electric motor / motors that rotate the wheels of the work machine are supplied with electric current with an output that depends on the position of the accelerator pedal.

The hydraulic driving force transmission of the forwarder shown in figure 1 can be e.g. a similar single-motor system as described in the applicant's previous patent application F1 20115671. In a corresponding manner, the electric drive transmission could be designed in such a way that all traction wheels are provided with their own electric motors which are e.g. DC motors, the power of which is adjusted by controlling the length and / or frequency of pulses in the supplied pulsed electric current. Between the electric motors and the wheels there may also be some transmission device (eg a planetary gear, a differential gear or the like) to form a suitable rotational speed and a suitable driving torque on the traction wheels.

Regardless of the design of the propulsion transmission, the propulsion transmission and the brake can be controlled with an electric control system. In a control system which applies the method according to the invention, such a control system includes a programmable controller which is placed in the front chassis 20 of the forwarder 10 shown in Figure 1 and which in this embodiment is so-called FRC (Frame Module) which controls i.a. drive transmission and service brake 12. When using a hydraulic drive transmission, the release of the service brake 12 with the programmable controller is controlled in a manner shown in the hydraulic circuit diagram of figure 2 by means of a control valve 14 belonging to solenoid valve 16. The solenoid valve 16 is controlled to hold 12 control valves 18 open and thus the operating brake 12 switched on after a time delay which depends on the inclination of the surface 28 and the weight of the working machine 10, when the driver begins to press the engine accelerator pedal 22, i.e. to increase the gear ratio of the power transmission. motlut. In a system according to Figure 2, the inclination of the surface 28 is measured with inclination sensors located in the front chassis 20 of the forwarder 10. The inclination sensors typically comprise e.g. a gyroscope and an inclinometer. An inclinometer measures an angle of inclination parallel to the direction of travel of the front chassis 20 of the forwarder 10 relative to the horizontal plane obtained with the gyroscope. This corresponds exactly to the actual slope of the surface 28, on which the forwarder 10 has been driven when the ground is an evenly inclined plane, along which the vehicle - i.e. the forwarder 10 regarding figure 1 - shall set in motion. The inclination sensors could be located alone or in addition also in the rear chassis 30, whereby the value of the slope of the surface could be determined according to the position of only the rear chassis 30 or both the rear chassis 30 and the front chassis.

In reality, the surface, on which e.g. a vehicle that goes on wheels moves, be uneven even in the space between the wheels, when driving on a terrain (outside the road network). At the time the vehicle sets in motion, however, the angle of inclination parallel to the direction of travel of the vehicle usually corresponds to the average pitch angle formed by the terrain contour under the wheels, as the force moving the vehicle downhill (regardless of the terrain contour at the time the vehicle sets) may be of the vehicle's gravity relative to the angle of inclination of its chassis in such a way that the force of gravity (Ötk) affecting the vehicle in the vertical direction corresponds to the following vector equation: Örk = Fs + Fr (1) 135 is a force in the direction of the ground surface parallel to the vehicle F, is a force in the transverse direction to the ground surface which is parallel to the vehicle Formula (1) describes a situation in which friction between the wheel of the vehicle and the ground surface, in the wheel bearings and in the force transmission are disregarded. For this reason, the real force 17 parallel to the earth's surface, which the brakes of a vehicle must maximally release in order for the vehicle not to start rolling downhill, is thus in practice always less than the theoretical maximum force E.

The actual force F, which is needed to keep the vehicle stationary, is of course directly proportional to the force É, so that the magnitude of the force FT which keeps the vehicle stationary at the time when it sets in motion is determined by the angle of inclination of the vehicle. in its direction of movement, since this very angle of inclination determines the direction in which the vehicle is to roll, even if the angle of inclination changed immediately after the beginning of the roll. Therefore, the required braking or stopping force measured with a tilt sensor based on the tilt angle of the vehicle is a good starting point when considering the force needed to prevent e.g. the scooter 10 shown the scooter 10 to move down the hill in a situation when the vehicle is set in motion in the opposite direction. In addition, it is clear that the magnitude of the force F, which keeps the vehicle still, is also dependent on its weight, since the force E increases directly in proportion to an increase in gravity G-tk, which is also clear from e.g. formula (1).

In the method according to the invention, however, there is no need to determine the required braking force exactly, since in practice the braking force of the working brake 12 of e.g. the forwarder 10 shown in Figure 1 is usually clearly larger than the magnitude of the force acting on it, the forwarder 10 not moving down the hill even if it were exposed to other external forces in addition to the force. with the direction of movement to determine an appropriate time delay between pressing the accelerator pedal and the (complete) release of the brake so that the forces holding the vehicle still between the hydraulic and mechanical time delay between the pressure of the accelerator pedal and the actual engagement of the drive transmission (the forces generated by the brake and the transmission power) can not be less than the force 13 ,.

The time delay is proportional to the angle of inclination and the weight of the working machine, since the greater the force FS and thus the force F, the longer the force transmission takes to produce a force sufficient to cancel the force É. a forwarder 10 according to figure 1 down the hill is prevented in a situation of starting in the opposite direction, by delaying the release of its working brake 12 by a time delay, the length of which increases in a certain ratio when the angle of inclination obtained from the inclination sensor increases.

In an embodiment of the method according to the invention, which is used for controlling the drive transmission and the working brake 12 of the forwarder 10 shown in Figure 1, the use of the above-mentioned time delay is determined according to a parameter WORK_BRAKE_RELEASE_DELAY_MlN_ANGLE which is set in the programmable controller. In this parameter a slope of the surface can be entered (ie the angle of inclination of the front chassis 20 in relation to the forwarder shown in Figure 1); with higher measured values of the angle of inclination, the time delay for disengagement of the service brake is applied. A parameter WORK_BRAKE_RELEASE_DELAY determines the length of the time delay for values of the Angle of Angle, which are higher than the minimum value determined by the parameter WORK_BRAKE_RELEASE_DELAY_MlN_ANGLE.

The WORK_BRAKE_RELEASE_DELAY time delay is determined from the tilt angle values measured in the programmable controller, e.g. using a linear dependency so that when the Angle of Angle exceeds the minimum value allocated for the parameter WORK_BRAKE_RELEASE_DELAY_MlN_ANGLE, the controller gives the parameter WORK_BRAKE_RELEASE_DELAY with the value: WORK_BRAKE_ha front chassis.

The magnitude of the Angle Coefficient k depends on the hydraulic and mechanical delay relating to the driving force transmission of the forwarder 10, and on the weight of the forwarder 10. The angular coefficient k can be determined e.g. through experiments, but it can also be allocated a value e.g. using a calculation model formed using empirical formulas based on experience, or e.g. on the basis of calculations based on precise modeling of the power transmission, or e.g. by giving it a provisionally calculated value, which if necessary is adjusted more appropriately on the basis of a test run or subsequent use experience. If the forwarder 10 had e.g. a propulsion transmission of the type described above which is based on electric motors, the value of the coefficient k would probably be different than in the case of a hydraulic propulsion transmission.

The diagram of Figure 3 shows an example of how the length of the parameter WORK_BRAKE_RELEASE_DELAY ie the time delay increases when the slope of the surface increases after the value of the parameter WORK_BRAKE_RELEASE_DELAY_MlN_ANGLE has been exceeded according to the linear dependence 2 determined (). As shown in Figure 3, when the slope of the surface is “hill angle” (ie aha) below a certain value (which corresponds to the value allocated for the parameter WORK_BRAKE_RELEASE_DELAY_MlN_ANGLE), the time delay is ie the value of the parameter WORK_BRAKE_RELEAS. In this case, the work brake 12 is released immediately when the machine operator begins to press the accelerator pedal 22. If the inclination of the surface (ie the angle of inclination aha of the front chassis of the work machine) is greater than the minimum value determined by the WORK_BRAKE_RELEASE_DELAY_MlN_ANGLE parameter, the WERE sets the controller. the time delay is a value greater than 0 s. In an embodiment of the method according to the invention, the minimum value is reached with the value of the inclination angle 3, and from there the time delay further increases e.g. 10 ms / °. When the slope of the surface 28 increases further from this minimum value, the time delay is then extended linearly according to the principle shown in Figure 3 when the slope of the surface 28 increases all the way to a predetermined maximum value WORK_BRAKE_RELEASE_DELAY_MAX_ANGLE, after which the parameter WORK_BRAKE_ELAY "Hill angle" in figure 3 increased further. The maximum value WORK_BRAKE_RELEASE_DELAY_MAX_ANGLE could be set e.g. when aha = 35 °. Thus, the time delay WORK_BRAKE_RELEASE_DELAY = 10 * (35-3) ms, if the angle coefficient k = 10 ms / °. In practice, of course, the controller does not have to calculate the time delay each time, but it can also be e.g. entered in a table in the controller's memory, from which the controller selects a value corresponding to the measured slope of the surface 28 of the parameter WORK_BRAKE_RELEASE_DELAY.

In the case of the forwarder 10 according to Figure 1, the effect of a change in its weight (eg due to load on the cargo space) is taken into account by changing the rate of increase of the time delay between minimum and maximum values. When the forwarder 10 is empty and without load, the value of the parameter WORK_BRAKE_RELEASE_DELAY increases according to figure 3. An increase in the weight of the forwarder 10 can be taken into account in the value of the parameter WORK_BRAKE_RELEASE_DELAY e.g. relative to the empty weight of the forwarder 10 so that its increase rate is due to the increased weight as follows: 11 woRk_BRAkE_RELEAsE_DELAv (m) = k- mmm / mo) -aha (s) in which Am is the increase of the forwarder's weight, m0 is the weight of the forwarder without load.

To determine the increase in weight, the forwarder 10 may comprise a weighing device placed in a suitable place (eg a force transducer or a strain transducer or the like). Another alternative is that the control system comprises the machine's weight determination system which calculates the weight gain or total weight according to how much load (tree trunks) is loaded in the cargo space, how work tools (eg how grab loaders) are attached to the forwarder and t.o.m. how much fuel is left in the machine's fuel tank. A third alternative is that the control system is provided with an option for manual entry of the amount of additional weight appearing for the time being, whereby the driver estimates the additional weight in the forwarder 10 and feeds it into the control system or selects suitable values in a reference table which can be displayed on a screen in the cab.

In the case of the forwarder 10 shown in Figure 1, the control system according to the invention operates in the manner described above always when the forwarder 10 is set in motion uphill on a sloping surface 28 and information about the inclination of the surface 28 is available. In other words, the direction of travel can be forwards or backwards (when reversing), if it is only uphill. To investigate this, e.g. the controller of the forwarder 10 shown in figure 1 is arranged to receive information from the control system about the direction of travel selected for the forwarder. Thus, the controller can calculate whether the direction of travel is in the direction of the higher end or the lower end of the forwarder 10, from which it is known whether the forwarder 10 is to move up or down the hill.

In a situation where at least one tilt sensor is out of order or out of order for some other reason, the controller controls the service brake to be disengaged immediately when the accelerator pedal is depressed, regardless of the terrain 'slope and direction of travel. This mode of operation ensures that the working brake does not remain engaged in any situation so that the power transmission could be damaged because it would try to rotate wheels that are locked. The method and control system according to the invention can be realized to a large extent in a manner which does not occur in the example applications presented above. The relationship between the surface inclination and the time delay shown in the diagram of Figure 3 is linear. In some applications, the time delay may also be non-linear depending on the slope of the surface. Also the minimum value determined by the parameter WORK_BRAKE_RELEASE_DELAY_MlN_ANGLE and the maximum value determined by the parameter WORK_BRAKE_RELEASE_DELAY_MAX_ANGLE can be determined differently depending on the case. In some embodiments, these minimum and maximum values are not used at all, or only the minimum or maximum value is used. Also for the determination of e.g. the inclination of the surface or the angle of inclination can be used different measurement methods and or sensors and / or e.g. a camera technique suitable for this, with which it is possible to determine the inclination of the surface or the angle of inclination of the vehicle caused by it in a manner corresponding to that described above, or in an even more precise manner. In some simpler embodiments of the procedure, the increase in the weight of the vehicle is not taken into account at all. This is suitable for e.g. such situations, in which the variation in the weight of the vehicle is insignificant, whereby a reasonable variation in the weight can be calculated sufficiently well by using an average total weight. On the other hand, the length of the time delay in any other embodiment may be so determined that it depends solely on the weight of the vehicle. In this case, it is determined whether the introduction of the time delay is solely on the basis of it, whether a certain minimum value for the slope of the surface (the value of the angle of inclination in the direction of the direction of travel of the working machine) is exceeded or not.

The method and control system according to the invention can also be used with work machines other in the field other than forest machines, such as e.g. excavators, excavators and agricultural tractors. In the case of forest machines, it can of course be used not only in forwarders of the type described above but also in e.g. different harvesters.

It should also be noted that the method according to the invention can also be applied for controlling the braking force and the driving force transmission when the vehicle is to be set in motion down the hill. In this case, the method and the steering system can prevent an unintentional movement of the vehicle in the same direction as the direction in which it is to be set in motion. Also in this case, an unintentional movement of the vehicle can cause slipping of its towing wheels, since the rotational speed of the wheels can be slower than the speed at which the forward movement takes place after switching on the propulsion transmission. However, the disadvantages caused by slipping in the same direction are usually less than the loss of the grip of the wheels due to an unintentional movement in the opposite direction, since slipping of the wheels caused by an accidental movement in the same direction can usually end more easily, e.g. . by means of a manually controllable brake, ie the working brake in work machines. If the steering system according to the invention according to the invention works both at start-up and at start-down, the system should know the direction in which the vehicle is set in motion, since the time delay associated with switching on the propulsion transmission is of course different at start-up. downhill than when starting uphill.

The method, the control system and the working machine according to the invention are thus not limited to the embodiments described above, but they can be varied within the scope of the appended claims.

Claims (15)

10 15 20 25 30 35 14 Patent claims: A method of controlling propulsion transmission of a vehicle, in which process the inclination of the surface (28) along which the vehicle (10) is driven is determined, and in which process the propulsion transmission and the brake (12) are adjusted according to the determined inclination of the surface. (28) and / or the determined weight (Gtk) of the vehicle (10), characterized in that when the vehicle (10) is set in motion along the inclined surface (28), the brake (12) of the vehicle (10) is disengaged after a period of time. delay (WORK_BRAKE_RELEASE_DELAY) from the clutch of the power transmission, and that the length of the time delay (WORK_BRAKE_RELEASE_DELAY) is adjusted depending on the inclination of the surface (28) and / or the weight of the vehicle (1 O) (GIK). Method according to claim 1, characterized in that the weight of the vehicle (Gtk) is determined according to it, if the vehicle (10) has a load and how heavy this load is. Method according to claim 1, characterized in that the weight (Gtk) of the vehicle (10) is determined by means of a weight measuring instrument in the vehicle (10). Method according to Claim 1, characterized in that the time delay is started when the transmission ratio of the power transmission of the vehicle (10) is greater than zero. Method according to claim 1, characterized in that below a certain predetermined limit value (WORK_BRAKE_RELEASE_DELAY_MAX_ANGLE) the time delay increases linearly as a function of the slope of the surface. Method according to claim 1, characterized in that the rate of increase of the time delay (WORK_BRAKE_RELEASE_DELAY) is adjusted according to the weight (Gtk) of the vehicle (10). Method according to Claim 1, characterized in that after a predetermined limit value (WORK_BRAKE_RELEASE_DELAY_MAX_ANGLE) the time delay is kept constant. 10 15 20 25 30 35 15 A control arrangement for controlling the propulsion transmission of a vehicle, comprising measuring means for determining the inclination of the surface (28) along which the vehicle (10) is driven, and a control system for controlling the propulsion transmission and brake (12) of the vehicle (10) according to the inclination of the surface (28) and / or the weight (Gtk) of the vehicle measured with the measuring devices, characterized in that the steering arrangement also comprises a means for delaying the brake (12), which is arranged to delay release of the brake (12) by a time delay. (WORK_BRAKE_RELEASE_DELAY) from the engagement of the propulsion transmission when the vehicle (10) moves along the inclined surface (28), and that the means for delaying the brake (12) is arranged to control the length of the time delay (WORKEL_BAYKE according to measure the inclination of the surface (28) and / or the weight (Gtk) of the vehicle (10). Steering arrangement according to claim 8, characterized in that the control system of the vehicle (10) comprises a programmable controller and that the means for delaying the brake (12) is a program stored in the programmable controller. Steering arrangement according to claim 8 or 9, characterized in that the measuring means comprise at least one inclination sensor which is arranged to measure the position of at least a part (20) of the vehicle (10) relative to the horizontal plane for determining the inclination of the surface (28). Steering arrangement according to one of Claims 8 to 10, characterized in that the steering arrangement comprises a means for determining the direction of travel for determining whether the vehicle (10) is to move up or down the inclined surface (28). Steering arrangement according to one of Claims 8 to 11, characterized in that the steering arrangement comprises a weight determination instrument for determining the weight (Gtk) of the vehicle (10). Work machine (10), characterized in that the work machine (10) comprises a control arrangement according to any one of claims 8-12. Work machine according to claim 13, characterized in that the work machine (10) is a hydraulic and / or electric work machine. 16 Work machine (10) according to claim 14 or 14, characterized in that the work machine (10) is a forestry machine.