Method for dynamic brake function testing on a mobile work machine and mobile work machine

Abstract

Method for testing the brake function of a mobile work machine, in particular an industrial truck, with a travel drive and a brake unit, wherein the brake function test is carried out taking into account a travel movement of the mobile work machine (1), wherein travel parameters of the travel drive and brake parameters of the brake unit occurring during the travel movement are recorded and evaluated in a data processing unit (2), characterized in that the travel parameters of the travel drive and brake parameters of the brake unit are compared with reference characteristics in the data processing unit (2), wherein the mobile work machine (1) is moved in a travel test sequence at a predetermined, constant travel speed against a brake force of the brake unit set to a partial force and the travel parameters and brake parameters recorded in the process are compared with the reference characteristics stored for this travel test sequence.

Description

The invention relates to a method for checking the braking function of a mobile work machine, in particular an industrial truck, having a travel drive and a braking unit, wherein the braking function check is carried out by including a travel movement of the mobile work machine, wherein travel parameters of the travel drive and braking parameters of the braking unit which occur during the travel movement are detected and evaluated in a data processing unit. The invention further relates to a mobile working machine for carrying out the method.Mobile work machines, such as industrial trucks, tractors or land and forest equipment, generally have an operating and a parking brake. The trouble-free functioning of the two brake systems formed by the operating brake and the parking brake can be proven at regular intervals during operation. For example, a daily check of the brake systems can be carried out in each case before vehicle operation. Regular brake tests are prescribed annually for industrial trucks in Germany, for example. In other EU countries, there are also corresponding guidelines. Moreover, maintenance recommendations of the manufacturers must be observed. In addition, after a repair at the brake system, a functional test is necessary.According to the present state of the art, brake testing in mobile work machines is usually carried out by the driver or a service technician as a test person.The service brake is usually tested by the test person manually performing full braking of the mobile working machine and evaluating the braking function according to the feeling of the test person or by measuring the braking distance. Another possibility is to carry out a brake test with a stationary vehicle and activated service brake.In this case, when the vehicle is stationary and the service brake is activated, the maximum motor drive torque of the traction drive is applied and the vehicle is checked for impermissible vehicle movement. The latter brake test can also be carried out automatically as a brake test program by a vehicle controller of the work machine and the test person can be informed of the result.The parking brake is normally tested by driving on a ramp which corresponds as far as possible to the maximum climbing capability of the vehicle according to the manufacturer's specification. Then, in the case of a vehicle standing on the ramp, the parking brake is activated and it is checked whether the vehicle is being held, i.e. not rolling. Another possibility is to manually activate the parking brake by the test person during the travel of the vehicle and to evaluate the braking function according to the feeling of the test person or by measuring the braking distance. Another possibility is to apply the maximum motor drive torque of the traction drive when the vehicle is stationary and the parking brake is activated, and to check the vehicle for an impermissible movement of the vehicle. The latter brake test can also be carried out automatically as a brake test program by a vehicle controller of the work machine and the test person can be informed of the result.An automatic test of the brake system when the vehicle is at a standstill is described, for example, in DE 10 2011 004 995 A1.The testing of the brake system according to the current state of the art has disadvantages both in manual testing and in the automated testing cycle.Manual testing of the brake systems is person-dependent and subjective. Moreover, it is inaccurate and prone to errors. Due to the great expenditure of time and the necessary measuring technique in a brake travel measurement, such a manual check is very complicated. Moreover, manual testing is poorly quantifiable and reproducible. A suitable ramp for testing the parking brake is also rarely available. Greater risks and more space requirements arise from high vehicle speeds.An automated test according to the prior art has the disadvantage that the mechanical service brake can only be tested up to the maximum drive torque of the traction drive. Often, however, the required service brake torque of the service brake is greater than the maximum drive torque of the traction drive. During the functional test of the service brake, the test person must actuate the brake transmitter, usually the brake pedal. Depending on the actuation force and quality of the sensing, inaccurate or incorrect test results are possible. During a brake test when the vehicle is at a standstill, the test person does not receive subjective feedback about the braking behavior, since there is no vehicle movement. Moreover, no result analysis is possible or it is more difficult, since no recording of a braking characteristic curve takes place. This makes it difficult to recognize trends and initiate a suitable vehicle reaction. There is no relationship between brake pedal force and braking force and no relationship between brake pedal travel and braking force. In addition, only a steady-state braking torque is applied or checked. Changes in the brake system, for example due to corrosion, wear, aging or chemical / physical effects, cannot be sufficiently detected in this type of test.DE 10 2013 114 561 A1 discloses a method of the generic type for checking the braking function in an industrial truck.DE 10 2010 026 411 A1 discloses a method and a device for carrying out a brake test on trailer and / or trailer vehicles which are coupled to a towing vehicle.The object of the present invention is to configure a method of the type mentioned at the beginning and a mobile work machine, in particular an industrial truck, for carrying out the method such that the disadvantages of the prior art mentioned are avoided.According to the invention, this object is achieved by the method in that the driving parameters of the driving drive and the braking parameters of the braking unit are matched with reference characteristic curves in the data processing unit, wherein the mobile working machine is moved in a driving test sequence at a predefined, constant driving speed against a braking force of the braking unit set to a partial force, and the driving parameters and braking parameters detected in the process are matched with the reference characteristic curves stored for this driving test sequence.The mobile working machine is thus driven at a certain speed against a partially engaged operating or parking brake.Advantageously, at least the driving speed and / or the rotational speed of the driving drive and / or the drive torque of the driving drive are detected as driving parameters, and at least the braking torque of the brake unit and / or the braking pressure of the brake unit and / or the braking force of the brake unit are detected as braking parameters.In this way, an automated or partially automated testing of the brake unit is possible, involving a vehicle movement. For optimum detection and testing of the brake state, travel speeds or rotational speeds of the travel drive and drive torques and braking torques can be combined as desired.In a preferred embodiment of the invention, the mobile work machine is accelerated in an acceleration test sequence from the stand up to a predefined travel speed against a braking force of the brake unit set to a partial force, and the travel parameters and brake parameters detected in the process are matched to the reference characteristic lines stored for this acceleration test sequence. The mobile working machine is thus accelerated against a partially engaged operating or parking brake.In a further embodiment of the invention, the mobile working machine is braked in a full braking test sequence from a predetermined travel speed by increasing the braking torque of the brake unit to a standstill, and the travel parameters and brake parameters detected in this case are matched to the reference characteristic lines stored for this full braking test sequence. At a specific speed, the braking torque is thus increased until the mobile working machine comes to a standstill.These test sequences can also be combined with one another, i.e. carried out successively in a suitable sequence. For example, the mobile work machine can first be accelerated in the acceleration test sequence against the partially engaged operating or parking brake to a specific travel speed and then braked to a standstill in a full brake test sequence. The driver should not feel a brake jerk during the test sequences. In the test procedures, the maximum travel speed can be limited to a low speed by the vehicle controller, for example, 3 km / h.In all three above-mentioned test sequences (acceleration test sequence, driving test sequence, full brake test sequence), rotational speeds of the driving drive, drive torque of the driving drive, brake torque of the brake unit, brake pedal travel or parking brake lever travel and / or brake pedal force or parking brake lever force, brake pressures and times are detected and evaluated and are matched to the corresponding stored reference characteristic lines.According to a further development of the inventive concept, the braking function test is carried out automatically and integrated into an intended driving mode and thus a driving sequence of the mobile work machine. In this way, during normal operation of the mobile working machine, a regular check of the braking function can be carried out without the driver noticing something of it.Alternatively, a test person, e.g. the driver, operator or a service technician, can intentionally trigger the brake function test at a time which is favorable for him. As a result, instead of a flat start-up test, a test according to requirements can be carried out. For this triggering, the test person can also receive a request from the vehicle controller of the work machine if, for example, too much time has elapsed since the last test or a test is considered to be appropriate by the vehicle controller of the work machine on the basis of other information.In a particularly preferred embodiment of the invention, it is provided for this purpose that a demand-based triggering of the brake function test is initiated by a vehicle controller. The data processing device of the brake function test is expediently integrated into the vehicle controller.In this case, the vehicle controller can automatically initiate the braking function test on the basis of specific operating parameters (e.g. distance travelled, frequency of braking processes, strength of braking processes, etc.) or at least prompt the test person for this purpose via corresponding displays. If the request is ignored repeatedly, appropriate interventions in the vehicle control, warning messages or even shutting down the mobile work machine can take place.According to a further development of the inventive concept, the driving parameters and braking parameters from a plurality of braking function checks are logged in the data processing unit. This allows the data processing unit to generate trends from multiple brake tests and more accurately analyze the brake state and determine optimal maintenance times. As a result, the economic efficiency during operation of the mobile working machine can be increased. In addition, by storing a plurality of test results, it is possible to detect the successful brake tests in the past, in order to facilitate, for example, a fault finding in the case of accidents.The information about the brake state can preferably be transmitted wirelessly to a service station or to a fleet management system. If necessary, an automatic request for maintenance or repair can be initiated.The invention further relates to a mobile work machine, in particular an industrial truck, for carrying out the method with a travel drive and a brake device, wherein the mobile work machine has a brake function checking device which comprises a data processing device which is operatively connected to sensors in the travel drive for detecting travel parameters and in the brake device for detecting brake parameters and is configured to evaluate the travel parameters of the travel drive detected during the travel movement and brake parameters of the brake device.In the case of such a mobile working machine, in particular an industrial truck, the object set is achieved in that the data processing device is configured to compare the driving parameters of the driving drive and braking parameters of the braking device detected during the driving movement with reference characteristic lines, wherein the mobile working machine is moved in a driving test sequence at a predefined, constant driving speed against a braking force of the braking unit set to a partial force, and the driving parameters and braking parameters detected in the process are matched to the reference characteristic lines stored for this driving test sequence.The invention is suitable for all types of mobile work machines. In particular, the invention is suitable for industrial trucks, e.g. counterweight forklifts. The invention can also be used with advantage in towing vehicles and agricultural vehicles and also fordust-related vehicles.The invention has a whole series of advantages:The brake function test, including the travel movement, gives the test person subjective feedback about the braking behavior. The test person does not have to rely solely on optical or acoustic feedback, as in the prior art. This increases the confidence in the test result of the brake unit. In addition, the invention enables a demand-optimized brake function test instead of a flat startup test. This does not result in unnecessary delays for the operator or driver. The optimum analysis of the test result additionally results in a gain in safety. Furthermore, by more accurately determining the optimum maintenance time, better economics result. It is to be regarded as an important advantage that a detailed result analysis is carried out by recording a brake characteristic curve over different rotational speeds, drive torques and braking torques. This allows better detection of trends and better vehicle response to the test result of the brake test.Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiment shown in the schematic figure:In the present exemplary embodiment, the mobile working machine is an industrial truck 1, for example a counterweight forklift, which has a service brake and a parking brake as the brake unit.For checking the braking function, the industrial truck 1 is accelerated from a standstill to a travel speed of 3 km / h, for example, when the parking brake is partially engaged. After this speed has been reached, the parking brake is released and full braking with the service brake is initiated by the vehicle controller 2, wherein the braking torque of the service brake is increased until the industrial truck 1 comes to a standstill. The industrial truck 1 comes to a standstill after a route x. The driving and braking parameters occurring during this combined acceleration-full braking test sequence are detected by sensors 4, 5 in the driving drive and in the braking device and evaluated in the data processing device 2 integrated into the vehicle controller 2.In this case, the profile of the travel speed, rotational speed of the travel drive, drive torque of the travel drive, braking torque of the parking brake and of the service brake, braking pressure of the parking brake and of the service brake and braking force of the parking brake and of the service brake are compared with reference characteristic curves stored in the data processing device 2 for this combined acceleration-full braking test sequence.From a correspondence of the profile of the parameters of the actual braking behavior with the reference characteristic curves for a setpoint braking behavior, it is possible to infer an intact state of the parking brake and service brake. If the reference characteristics deviate, maintenance of the brakes is necessary. The respective result of the brake function test is displayed to a test person, for example a driver or service technician, of the mobile work machine on a display 3.In addition, the respective result of the brake function test can be transmitted wirelessly via an Internet connection to a service station. Thus, maintenance of the brakes can be initiated promptly.

Claims

Method for checking the braking function in a mobile working machine, in particular an industrial truck, having a travel drive and a braking unit, wherein the braking function check is carried out by including a travel movement of the mobile working machine (1), wherein travel parameters of the travel drive and braking parameters of the braking unit which occur during the travel movement are detected and evaluated in a data processing unit (2), characterized in that the travel parameters of the travel drive and braking parameters of the braking unit are matched with reference characteristic curves in the data processing unit (2), wherein the mobile working machine (1) is moved in a travel test sequence at a predefined, constant travel speed against a braking force of the braking unit which is set to a partial force, and the travel parameters and braking parameters detected in the process are matched with the reference characteristic curves stored for this travel test sequence.Method according to Claim 1, characterized in that at least the driving speed and / or the rotational speed of the driving drive and / or the drive torque of the driving drive are detected as driving parameters and at least the braking torque of the brake unit and / or the braking pressure of the brake unit and / or the braking force of the brake unit are detected as braking parameters.Method according to Claim 1 or 2, characterized in that, in an acceleration test sequence, the mobile working machine (1) is accelerated from a standstill to a predefined travel speed against a braking force of the brake unit set to a partial force, and the travel parameters and brake parameters detected in the process are matched to the reference characteristic lines stored for this acceleration test sequence.Method according to Claim 1 or 2, characterized in that, in a full braking test sequence, the mobile working machine (1) is braked from a predefined travel speed by increasing the braking torque of the brake unit until it stops, and the travel parameters and brake parameters detected in the process are matched to the reference characteristic curves stored for this full braking test sequence.Method according to one of Claims 1 to 4, characterized in that the braking function test is carried out automatically and is integrated into an intended driving mode of the mobile working machine (1).Method according to one of Claims 1 to 5, characterized in that triggering of the brake function test according to requirements is initiated by a vehicle controller.Method according to one of Claims 1 to 6, characterized in that the driving parameters and braking parameters from a plurality of braking function checks are logged in the data processing unit.Mobile working machine, in particular industrial truck, for carrying out the method according to one of Claims 1 to 7 having a travel drive and a braking device, wherein the mobile working machine (1) has a braking function checking device which comprises a data processing device (2) which is operatively connected to sensors (4, 5) in the travel drive for detecting travel parameters and in the braking device for detecting braking parameters and is configured to evaluate the travel parameters of the travel drive detected during the travel movement and braking parameters of the braking device, characterized in that the data processing device (2) is configured to compare the travel parameters of the travel drive detected during the travel movement and braking parameters of the braking device with reference characteristic curves, wherein the mobile working machine (1) in a travel checking sequence matches a predefined characteristic curve, The vehicle is moved at a constant speed against a braking force of the brake unit set to a partial force, and the driving parameters and braking parameters detected in the process are matched to the reference characteristic lines stored for this driving test sequence.

Images