ADJUSTMENT PROCEDURE FOR SERVICE BRAKE FUNCTIONS FOR MOBILE WORK MACHINES AND A BRAKE ARRANGEMENT

Description

Technical area

[0001] The present invention relates to a method for adjusting service brake functions for mobile work machines, in particular agricultural machines and construction machines, according to the preamble of claim 1, and to a brake arrangement for such mobile work machines according to the preamble of claim 8.

[0002] Mobile work machines are used in a variety of areas, each with different ground conditions. Operation on slopes or hills, in particular, can pose problems for such heavy work machines. Therefore, mobile work machines typically have an electrically activated parking brake, which is used, for example, to hold the vehicle on a slope. However, this is often insufficiently adjustable and not robust enough to perform slope-holding or even emergency braking functions.

[0003] DE198 35 937 A1 and DE 196 48 559 A1, which are considered closest to the subject matter of claim 7, each disclose the subject matter of the preamble of claim 1. Further relevant prior art can be found in WO96 / 11 826 A1 or DE 10 2021 109 670 A1.

[0004] The object of the present invention is therefore to provide an adjustment method which enables automatic actuation of a service brake function and thereby provides easier handling.

[0005] The object is achieved by a setting method of service brake functions for mobile work machines according to claim 1 and a brake arrangement according to claim 7.

[0006] The inventive adjustment method for service brake functions for mobile work machines begins with the detection of at least one external signal via at least one sensor and its forwarding to a control unit. In the control unit, the at least one detected external signal is processed, for example, by filtering, merging, or converting it, so that a target brake pressure is determined and an electrical valve current is calculated from it. The calculated valve current is used to control a control valve of a brake actuation pedal and is therefore forwarded to the control valve in a further step. The control valve of the brake actuation pedal then sets a brake pressure in a hydraulic brake circuit so that at least one preselected brake function mode, which was activated via a human-machine interface, is executed.According to the invention, the brake pressure is automatically adjusted from a preselected operating mode. According to the invention, the external signal is determined from continuous environmental monitoring of the mobile work machine.

[0007] Two brake circuits can also be controlled using the method according to the invention. Two target brake pressures and two valve currents are then calculated, which are used to adjust two control valves.

[0008] Preferably, the control unit can communicate with the vehicle speed sensor via a wired or wireless connection so that measurement signals can be transmitted from the vehicle speed sensor to the control unit.

[0009] Furthermore, the control unit can preferably be configured to monitor the external signals in the form of external vehicle data such as vehicle inclination, accelerator pedal position, drive torque and / or inclination of the work vehicle using the at least one sensor.

[0010] The required valve current to actuate the control valve is preferably calculated using characteristic maps, lookup tables, a suitable mathematical formula, and / or algorithms that relate the measurement signals of the work vehicle to the measured values. If the monitored measured value, such as the vehicle's inclination or the drive torque, exceeds a threshold, the control unit can be configured to determine that the work vehicle is on a slope. To determine whether the work vehicle actually stops on the slope, a threshold value can also be included for a period of time.

[0011] Preferably, several braking function modes, which were previously defined in the control unit, can be activated simultaneously.

[0012] Particularly advantageous is the ability to adapt the respective braking function modes. For example, the brake pressure can be set higher to prevent the heavy vehicle from rolling downhill on steep inclines.

[0013] Preferably, a hill hold mode, i.e. hill start assist, or a down hill braking mode, i.e. assisted braking when driving downhill or stopping on a hill, can be set. Both the hill hold mode and the down hill braking mode prevent the vehicle from unintentionally rolling away when stationary or when starting on an inclined road. As soon as the work machine is braked to a standstill, at least one sensor detects that there is neither a wheel speed nor an incline angle. As soon as these signals are present simultaneously, the brake pressure occurring at the moment of standstill is stored and maintained. If the driver subsequently presses the brake pedal, the brake pressure in the brake circuit is initially maintained for, for example, 3 to 6 seconds if the threshold value, which could be the engine torque, is exceeded.This prevents the work vehicle from rolling backward. After, say, five seconds, the brake pressure in the brake circuit is reduced, allowing the brakes on the wheels to release and the vehicle to move again. This process also occurs in downhill braking mode, i.e., when driving down a hill.

[0014] Furthermore, a brake assembly according to the invention is disclosed, which is intended and designed for mobile work machines, in particular agricultural machines / tractors and construction machines. The brake assembly comprises a hydraulic brake actuation pedal with a control valve arranged thereon for adjusting a brake pressure. Furthermore, the brake assembly comprises a hydraulic circuit, which is divided into a first hydraulic circuit and a second hydraulic circuit. The first hydraulic circuit drives the chain or wheel or wheels on the left side of the work machine, and the second hydraulic circuit drives the chain or wheel or wheels on the right side of the work machine. Furthermore, the first hydraulic circuit is connected to a first actuation section of the brake actuation pedal, wherein the second hydraulic circuit is connected to a second actuation section of the brake actuation pedal.An electronic control unit is arranged on the control valve to transmit a calculated valve current to the hydraulic brake actuation pedal. Furthermore, the brake assembly includes a human-machine interface, which is coupled to the electronic control unit and can be manually operated by the driver. Furthermore, the brake assembly includes at least one sensor designed to detect at least one external signal from the work machine.

[0015] According to the invention, the brake arrangement is designed to carry out the previously described adjustment method of service brake functions.

[0016] Preferably, the human-machine interface is designed as an external control element, which can take the form of a display, a switch, a button, or a joystick. Alternative designs for manual operation could also be implemented.

[0017] In a further development, the mobile work machine has an electric drive. Since, in contrast to hydrostatically driven mobile work machines, braking is not achieved via a principle-based holding torque, i.e., an enclosed hydraulic volume that is only released with a time delay due to a leak (hydraulic control), but rather via an electrohydraulic control, the implementation of various braking functions, such as the hill-hold mode, is particularly advantageous.

[0018] Preferably, the hydraulic brake actuation pedal has first and second subassemblies configured to be assembled to one another in a pre-assembled manner. The first subassembly includes the first control piston and a first actuation piston, each movable along a first axis, with at least one first spring disposed between the first control piston and the first actuation piston along the first axis. The first subassembly further includes the second control piston and a second actuation piston, each movable along a second axis, with at least one second spring disposed between the second coil and the second actuation piston along the second axis, the first and second axes being parallel to one another. The second subassembly includes third and fourth actuation pistons.The third actuating piston is movable along the first axis and has a third contact surface capable of contacting a first contact surface of the first actuating piston. The fourth actuating piston is movable along the second axis and has a fourth contact surface capable of contacting a second contact surface of the second actuating piston.

[0019] Preferably, the first and second assemblies are fully pre-assembled prior to assembly. Preferably, at least one actuating means is present which acts on the third and / or fourth actuating piston to actuate the brake. Preferably, the first and second actuating pistons are only actuated via the third and fourth actuating pistons, respectively. Furthermore, the first to fourth contact surfaces are flat and oriented perpendicular to the first and second axes, respectively. Preferably, an outer diameter of the first actuating piston at the first contact surface is larger than an outer diameter of the first control piston. Preferably, an outer diameter of the second actuating piston is larger than an outer diameter of the second control piston. Preferably, the first and / or second control piston are part of a pressure reducing valve.

[0020] It can be provided that the second subassembly has a second body that receives the third and fourth actuating pistons, wherein the second body is attached to a first body of the first subassembly and wherein the first body receives the first and second coils, the first and second actuating pistons and the at least one first spring and the at least one second spring. The diameter of the third actuating piston at the third contact surface is smaller than a diameter of the first actuating piston at the first contact surface. The second body limits movement of the first actuating piston along the first axis and / or a diameter of the fourth actuating piston at the fourth contact surface is smaller than a diameter of the second actuating piston at the second contact surface, wherein the second body limits movement of the second actuating piston along the second axis.In this embodiment, the diameter of the first and fourth actuating pistons can be flexibly adjusted to the selected actuation type. The first and second actuating pistons are identical for all actuation types.

[0021] Preferably, the first and second bodies abut one another on a flat surface that is perpendicular to the first and second axes. Preferably, the first and second bodies and the first and second slides define an outlet chamber that is fluidly connected to an outlet port of the first body. The pressure in the outlet chamber preferably acts on the first and second actuating pistons from all sides, and the pressure in the venting chamber preferably acts evenly on the first and second actuating pistons from all sides, so that it does not generate a net force on the first and second actuating pistons, respectively.

[0022] It can be provided that the third actuating piston, together with the second body, delimits a first chamber, wherein the volume of the first chamber increases when the third actuating piston is moved in the direction of the first control piston and / or wherein the fourth actuating piston, together with the second body, delimits a second chamber, wherein the volume of the second chamber increases when the fourth actuating piston is moved in the direction of the second control piston. The second assembly comprises at least one control valve which is fluidically connected to the first and / or the second chamber. In this embodiment, electromechanical actuation of the brakes is provided. It should be noted that the corresponding control pressure does not act directly on the first or second control piston. Instead, the corresponding effect occurs via the at least one first or second spring.This enables better fine-tuning of the braking force and avoids oscillations in the braking force. Preferably, the at least one control valve is a pressure reducing valve whose output pressure is connected to the first and / or second chamber. Preferably, a setting pressure of the control valve is set electrically. If a control valve is present, this control valve is preferably fluidically connected to the first and second chambers in parallel, so that the first and second chambers have the same pressure. If two control valves are present, the first and second chambers are preferably each fluidically connected to a separate control valve. With this embodiment, it is possible to have electromechanically actuated hydraulic brake actuation pedals, wherein a mechanical possibility for directly actuating the slides may or may not be present.

[0023] It can be provided that the first and second control pistons each have a separate pressure source, wherein the at least one control valve is connected to said at least one pressure source for pressure supply. Preferably, a shuttle valve is provided, wherein the pressure sources are connected to an input side of the shuttle valve, wherein an output side of the shuttle valve is connected to the at least one control valve. Preferably, the shuttle valve is arranged in the second subassembly. Each pressure source comprises a hydraulic accumulator. If two control valves are provided, each control valve can be connected to a separate pressure source.

[0024] It can be provided that the hydraulic brake actuation pedal comprises a movable actuation element configured to actuate the first and second control pistons in parallel, wherein there is a third subassembly configured to be pre-assembled to the second subassembly, wherein the third subassembly comprises the actuation element. The actuation element is configured to contact the third and fourth actuation pistons in parallel. In this embodiment, a purely mechanical actuation of the brakes is provided. Preferably, the actuation element is a pedal that can be actuated by a human foot. It is also possible to use an actuation element designed for actuation by a human hand.The said contact between the actuating element and the third and / or fourth actuating piston can be canceled when the actuating element is not actuated.

[0025] It can be provided that the third assembly comprises a third body which is fastened to the second body, wherein the actuating element is movably mounted on the third body, wherein a rocker is pivotally mounted on the remaining actuating element with respect to a third axis, and the rocker has a first and a second free end which are located on opposite sides of the third axis, wherein the first free end can contact the first actuating section and the second free end can contact the second actuating section. In this embodiment, the force of the actuating element can be evenly distributed between the first and second coils. If one of the coils blocks due to a fault, the other coil remains functional. Preferably, the second and third bodies abut one another on a flat surface which is perpendicular to the first and second axes.

[0026] It can be provided that the actuating element is a pedal which is pivotally mounted on the third body with respect to a fourth axis, wherein the fourth axis is perpendicular to the first and second axes and the distance from the fourth to the first axis and from the fourth to the second axis is the same. Preferably, a sensor is provided which is designed to measure the pivot angle of the pedal with respect to the fourth axis. Preferably, the sensor makes use of the Hall effect. Preferably, the third axis is perpendicular to the fourth axis and is arranged between the first and second axes. Short description of the characters

[0027] Fig. 1 shows a representation to illustrate an adjustment method according to the invention for service brake functions for mobile work machines in interaction with a brake arrangement according to the invention. Fig. 2shows a sectional view of an embodiment of a hydraulic brake actuation pedal according to a first embodiment of the invention.

[0028] In a first step S1, according to Fig. 1 External signals are detected by at least one sensor 06 and / or a human-machine interface 05, which are connected to a control unit 02, and forwarded to the control unit 02. The at least one sensor 06 can detect vehicle data such as driving speed, vehicle inclination, drive torque, and the like. The human-machine interface 05 can be designed as a display, button, switch, or joystick and can be arranged within the mobile work vehicle.

[0029] The continuous detection of at least one external signal can be performed automatically. Manual selection S6 of a braking function mode is performed via the human-machine interface 05. Furthermore, the driver can perform an adaptation S7 of the braking function modes via the human-machine interface 05.

[0030] In the subsequent step, the external signals are processed and a target brake pressure S2 is determined, for example by processors in the control unit 02 (not shown). The processing of the external signals can involve filtering, combining, or smoothing the signals. Based on the target brake pressure, a valve pressure flow is calculated S3 in a third step, which is then forwarded S4 to a control valve 70 connected to the control unit 02. The control valve 70 is arranged on a brake actuation pedal 10 and is designed to adjust a brake pressure.

[0031] In a final step, the control valve 70 receives the electrical valve current determined by the control unit 02 and sets a brake pressure in one of the two brake circuits 03, 04, which are arranged on the control valve 70. The vehicle data detected by the at least one sensor 06, such as inclination angle, drive torque, etc., can be used to determine the position of the vehicle and whether the previously determined threshold values ​​have been exceeded, so that the control valve 70, via the control unit 02 and the brake actuation pedal 10, brakes and / or blocks the brake circuit 03, 04, so that a suitable brake pressure is set through the desired brake function mode and its adaptation.

[0032] As soon as the control unit 02 detects that the threshold value of the respective vehicle data has been undershot again, a signal is sent via the control valve 70 to the hydraulic brake pedal 10 and the blocked hydraulic circuit 03, 04 is released again. The mechanical implementation of the braking process using the brake pedal 10 is described in the Fig. 2 shown and described in the following sections.

[0033] Fig. 2shows a sectional view of a hydraulic brake pedal 10 according to a first embodiment of the invention. The hydraulic brake pedal 10 comprises a first, a second, and a third subassembly 20; 60; 80. Each subassembly 20; 60; 80 can be completely preassembled. Subsequently, the entire hydraulic brake pedal 10 is assembled from the three assemblies 20; 60; 80 mentioned. The assemblies 20; 60; 80 mentioned are preferably connected to one another via screws. In particular, the third assembly 60 exists in various variants, wherein Fig. 2shows one of the more sophisticated variants of the second assembly 60, which allows for purely manual operation of the brakes 100 and electrohydraulic operation via the first control valve 70. To achieve different operating variants, the second assembly 60 in particular must be modified. The first and third subassemblies 20; 80 can be left unchanged. Therefore, the first and third assemblies can be manufactured in high volumes and at low cost.

[0034] The first subassembly 20 has a first and second brake pressure connection 24; 26, each connected to a corresponding brake 100. The brake 100 can be a disc brake or a drum brake. Multiple brakes can be connected in parallel to each brake pressure connection 24; 26. Both brakes 100 are actuated in parallel by an actuating element 82 in order to have two independent brake circuits and increase safety. In this embodiment of the invention, a purely mechanical coupling exists between the actuating element 82 and the first and second control pistons 41; 51 when the third subassembly 80 is present. This allows the brake system to operate safely even if the electrohydraulic actuation fails. The actuating element 82 is part of the third subassembly 80.

[0035] Furthermore, the first assembly 20 has a first and a second supply connection 23; 25. These are typically each connected to one of two independent pressure sources 101 to increase safety. The pressure sources 101 preferably each comprise a hydraulic accumulator. Preferably, a system for filling the accumulators is provided, which is Fig. 1 is not shown.

[0036] The first subassembly 20 has a vent port 22 connected to a tank 102. The hydraulic brake pedal 10 is preferably operated with hydraulic oil rather than the DOT brake fluid used in motor vehicles. The hydraulic brake pedal 10 is preferably used in vehicles that have hydraulic working functions and / or a hydraulic drive system, with all hydraulic functions, including the brake, using a common pump for hydraulic pressure supply.

[0037] The first and second sliders 41; 51 are movable along a first and second axis 40; 50, respectively, wherein the first and second axis 40; 50 is a central axis of the corresponding first or second slider 41; 51. The first and second axes 40; 50 are parallel to one another. The first subassembly 20 has a first body 21 which bears against a second body 61 of the second subassembly 60 with a flat surface that is perpendicular to the first and second axes 40; 50. The second body 61 limits the movement of the first and second actuating pistons 42; 52 with said flat surface. The third subassembly 80 has a third body 81 which bears against the second body 61 with a flat surface that is perpendicular to the first and second axes 40; 50.

[0038] Fig. 1shows the first control valve 70 symbolically, wherein the first control valve 70 is part of the second subassembly 20 in the embodiment shown. The first control valve 70 is designed as a pressure reducing valve that is electrically operated, i.e. the output pressure of the first control valve 70 is proportional or inversely proportional to the current that controls the first control valve 70. The accumulators of the two independent pressure sources 101 are preferably each connected to an inlet side of the shuttle valve 103, wherein the corresponding outlet side is connected to a supply connection of the first control valve 70. The exhaust air connection of the first control valve 70 is connected to the tank 102.

[0039] In the first embodiment according to Fig. 1The first and second chambers 68; 69 of the second subassembly 60 are connected in parallel to the first control valve 70, so that both chambers 68; 69 have the same pressure. It is possible to provide a separate control valve for each of the first and second chambers 68 and 69. List of reference symbols

[0040] 02 Control unit 03 First hydraulic brake circuit 04 Second hydraulic brake circuit 05 Human-machine interface 06 Steering angle sensor 10 Hydraulic brake actuation pedal 20 First subassembly 21 First body 22 Exhaust port 23 First supply port 24 First brake pressure port 25 Second supply port 26 Second brake pressure port 40 First axle 41 First control piston 42 First actuation piston 50 Second axle 51 Second control piston 52 Second actuation piston 60 Second subassembly 61 Second body 62 Third actuation piston 68 First chamber 69 Second chamber 70 First control valve 80 Third subassembly 81 Third housing 82 Actuation element 100 Brake 101 Pressure source 102 Reservoir / tank 103 Shuttle valve

Claims

1. Adjustment method for service brake functions of mobile working machines, in particular agricultural machines and construction machines, comprising the following steps: - sensing at least one external signal via at least one sensor (06) and forwarding (S1) it to a control unit (02); - processing the at least one external signal and determining (S2) a setpoint brake pressure on the basis of at least one external signal; - calculating (S3) a necessary electrical valve current based on the determined setpoint brake pressure; - forwarding (S4) the calculated valve current to a control valve (70) of a brake actuating pedal (10); and - adjusting (S5) a brake pressure in a hydraulic brake circuit (03, 04) via the brake actuating pedal (10), with the result that a service brake function is set, wherein the calculation (S3) of the valve current is carried out by a preselection (S6) of brake function modes via a man-machine interface (05), wherein the adjusting of service brake functions is carried out automatically after the preselection of a brake function mode, characterized in that the external signal is determined from continuous environment monitoring of the mobile working machine.

2. Adjustment method of service brake functions according to Claim 1, characterized in that the forwarding of the at least one external signal to the control unit (02) is carried out via a wired or wireless connection.

3. Adjustment method of service brake functions according to Claim 1 or 2, characterized in that the calculation (S3) of the necessary valve current is carried out with the aid of characteristic diagrams and / or mathematical formulae and / or algorithms and / or a predetermined threshold value.

4. Adjustment method of service brake functions according to one of Claims 1 to 3, characterized in that several brake function modes can be or are selected at the same time.

5. Adjustment method of service brake functions according to one of Claims 1 to 4, characterized in that adaptations are made to the brake function modes.

6. Adjustment method of service brake functions according to one of Claims 1 to 5, characterized in that the brake function modes are configured as a hill-hold mode and / or as a downhill-braking mode.

7. Brake arrangement for mobile working machines comprising: a hydraulic brake actuating pedal (10) for adjusting a brake pressure; a control valve (70) which is located on a hydraulic brake actuating pedal (10); a hydraulic circuit which is divided into a first hydraulic circuit (03) and a second hydraulic circuit (04), wherein the first hydraulic circuit (03) is arranged and operatively connected by way of a first actuating section of the brake actuating pedal (10), and the second hydraulic circuit (04) is arranged and operatively connected by way of a second actuating section of the brake actuating pedal (10); an electronic control unit (02) which is connected to the control valve (70) to transmit a calculated electrical valve current via the control valve (70) to the hydraulic brake actuating pedal (10); a man-machine interface (05) which is connected to the electronic control unit (02); and at least one sensor (06) for detecting at least one external signal of the mobile working machine, characterized in that the brake arrangement is designed to carry out the electrohydraulic brake method according to Claims 1 to 6.

8. Brake arrangement according to Claim 7, characterized in that the man-machine interface (05) is designed as an external operating element.

9. Brake arrangement according to Claim 7 or 8, characterized in that the mobile working machine has an electrified or electric drive.

10. Brake arrangement according to one of Claims 7 to 9, characterized in that the hydraulic brake actuating pedal (10) comprises a first and a second slide (41, 51), a first and a second subassembly (20; 60), which are configured in such a way that they can be mounted on one another in a pre-assembled manner.

11. Brake arrangement according to Claim 10, characterized in that the first subassembly (20) comprises the first slide (41) and a first actuating piston (42), each of which is movable along a first axis (40), wherein at least one first spring (44) is arranged between the first spool (41) and the first actuating piston (42) along the first axis (40), wherein the first subassembly (20) comprises the second slide (51) and a second actuating piston (52), each of which is movable along a second axis (50), wherein at least one second spring (54) is arranged between the second slide (51) and the second actuating piston (52) along the second axis (50), wherein the first and the second axis (40; 50) are parallel to each other, and / or wherein the second subassembly (60) comprises a third and a fourth actuating piston (62; 63), wherein the third actuating piston (62) is movable along the first axis (40), wherein it has a third contact surface which can make contact with a first contact surface (43) of the first actuating piston (42), wherein the fourth actuating piston (63) is movable along the second axis (50), wherein it has a fourth contact surface which can make contact with a second contact surface (53) of the second actuating piston (52).