Device for measuring the actuation force of a parking brake

Abstract

A device for measuring the amount of force required to apply a mechanical parking brake of a motor vehicle. The device comprises a body adapted to be mounted to a parking brake lever of the type which can be manually pivoted about an axis to apply the parking brake. When the body is mounted to the lever, first and second force sensors are disposed on the body at different distances from the pivot axis of the lever. The force sensor measures the force applied to the lower surface of the lever to cause the lever to pivot when the lever is pulled upwards to apply the parking brake. An angle sensor is disposed on the body and measures the actuation angle at which the lever pivots about the pivot axis during application of the parking brake. An electronic unit reads the respective first and second forces applied to the force sensors during pivoting of the lever, thereby calculating an effective actuation force applied at a reference point on the lever, and relating the effective actuation force to the actuation angle.

Description

Technical Field

[0001] The invention relates to a method for determining a single effective actuation force at a reference point, which is applied by a person to a brake lever when operating a parking brake at the handle of the brake lever, the brake lever being pivotably supported about a lever pivot axis of a mechanical parking brake of a vehicle, in particular a motor vehicle.

[0002] The invention further relates to a related force measuring device, in particular a device for determining a single effective actuating force at a reference point, which is applied by a person to a brake lever when operating a parking brake at the handle of the brake lever, the brake lever being pivotably supported about a lever pivot axis of a mechanical parking brake of a vehicle, in particular a motor vehicle. Background Art

[0003] The development and manufacture of mechanical parking brakes which are operated by a person via a brake lever which is pivotably supported about a lever pivot axis includes, among other things, necessary tests for proper operation of the vehicle. In particular, by means of tests of this type, compliance with legal or regulatory requirements can be tested, which requirements may, for example, specify the maximum operating force to be applied to the brake lever which is necessary to achieve a clamping force of the parking brake which is sufficient to hold the vehicle securely on a defined gradient or slope.

[0004] In order to test the parking brake function, it is necessary to measure the actuation force applied by a person to the brake lever when operating the parking brake, for example by means of a force sensor. However, in this case, it has been shown that the actuation force applied by a person to the brake lever can be significantly influenced by several factors, including a) the person operating the brake lever, b) the geometric arrangement determined by a certain application of the force sensor to the brake lever or its relative position to the brake lever, c) the direction of action of the actuation force applied by the person to the brake lever, and d) their experience with the performance of the test method. It has been found that the factors cause the measurement results regarding the actuation force applied by the person to the brake lever to be subject to large fluctuations, so that the measurement results can provide relatively inaccurate evidence about the actuation force to be actually applied to the brake lever for a sufficient clamping or braking effect of the parking brake caused thereby. Therefore, when using traditional measurement system analysis to evaluate the measurement quality of the measurement method or system, in particular with respect to its repeatability and reproducibility, such a measurement method can provide an inadequate evaluation.

[0005] There is therefore a need for a force measuring method and a force measuring device for a mechanical parking brake which simply, reliably and precisely measures or determines the actuation force applied to the brake lever when the parking brake is operated by a person, so as to achieve a significant improvement in repeatability and reproducibility. In particular, the method and the device should also be simple to apply in a vehicle, i.e. in a vehicle in which the parking brake is already correctly installed, so that the device should be compact and easy to manage and so as to be fitted to an existing parking brake lever without high costs. Summary of the invention

[0006] Against this background, it is an object of the present invention to provide a method of this type and a device of this type.

[0007] It should be noted that the features mentioned individually in the following description can be combined with each other in any technically reasonable manner and describe further embodiments of the invention. This description, in particular in conjunction with the accompanying drawings, further characterizes and specifically describes the invention.

[0008] As disclosed herein, a method for determining a single effective actuation force at a selected reference point, which is applied by a person to a brake lever when operating a parking brake via a defined operating surface on the handle of the brake lever, the brake lever being pivotably supported about a lever pivot axis of a mechanical parking brake of a vehicle, the effective actuation force acting at the reference point being determined by at least two actuation force components acting orthogonally to the operating surface. When the parking brake is operated by the person, each operating force component is measured by at least one force sensor as a function of the actuation angle of the brake lever. Thus, the disclosed method provides at least as many force sensors as actuation force components to be measured. Furthermore, according to the disclosed method, at least two force sensors are arranged at different distances from the lever pivot axis, and thus in each case an actuation force component to be measured and acting orthogonally to the operating surface acts on the force sensors when the parking brake is operated by the person.

[0009] In this case, the distance between the lever pivot axis and the respective force sensor refers to the length of the shortest connection path between the lever pivot axis and the respective force sensor, for example the length to the (geometric) center point of the respective force sensor. The force sensors can be implemented identically, for example with regard to the design, the operating principle, their dimensions, etc. However, the force sensors do not have to be identical.

[0010] An effective force (i.e. an effective actuating force) is herein understood to mean a force which causes a change in position (i.e. a pivoting of the brake lever about the lever pivot axis) and which therefore serves to generate a torque relative to the lever pivot axis. Forces of this type are therefore always oriented perpendicularly or orthogonally to the corresponding (real or virtual) lever or torque arm, which is pivotable about the lever pivot axis. Furthermore, the direction of action of the effective actuating force in this case is also always parallel to the pivot plane of the brake lever, which is defined by the pivoting movement of the brake lever.

[0011] In the context of the present invention, the actuation angle is the pivot angle of the brake lever relative to its initial position, in which the parking brake is not operated and is therefore not applied and does not cause any braking effect. In its initial position, according to said definition, the value of the actuation angle of the brake lever of the parking brake is zero.

[0012] According to the disclosed method, the effective actuation force at the reference point is therefore not measured directly, but rather determined or calculated indirectly from at least two actuation force components acting perpendicularly or orthogonally to the operating surface and measured by corresponding force sensors. A significant advantage over the direct measurement of the total applied actuation force by only one force sensor is that the result of the effective actuation force determined according to the invention is subject to significantly smaller fluctuations, which can be caused, for example, by operating forces exerted on the brake lever with different force action directions in the case of multiple measurements by the same person or even by different persons. The actuation force components, which are usually applied by the hand or finger of the operator at different distances from the lever pivot axis and act perpendicularly or orthogonally to the operating surface, are detected in a significantly realistic manner by at least two force sensors arranged at different distances from the lever pivot axis and are used to detect or determine the effective total actuation force at the reference point, which leads to a significant improvement in the measurement accuracy.

[0013] Furthermore, the disclosed method enables the determination of a suitable reference point, which can also be referred to as a force reference point, in the case of a measuring method with a high measurement quality (in particular with regard to repeatability and reproducibility), at which the effective actuating force determined according to the invention cannot be directly measured at all using conventional measuring devices or force sensors, for example in a handle inside a brake lever.

[0014] The disclosed method thus significantly reduces the influence of the person operating the parking brake during the implementation of the method. Furthermore, the fluctuations of the results are significantly reduced, so that the method according to the invention allows qualitatively higher value conclusions for the development and manufacture of parking brakes for vehicles. Likewise, the method according to the invention can be used for quality testing of the proper adjustment of the parking brake after installation in a vehicle.

[0015] According to an advantageous embodiment of the invention, at least two force sensors are arranged on the underside of the handle of the brake lever, wherein the corresponding actuation force components are applied by the pad providing the operating surface when the parking brake is operated by a person. The underside of the handle is understood to mean the side of the handle which is essentially facing the floor of the vehicle with the brake lever installed in the vehicle. In this way, a person can operate the brake lever in the usual way by applying an upwardly directed or "pulling" force to the underside of the handle. During this, a compressive, tensile or bending force acts on the sensors, depending on the various known types of force sensors used, which measure force components according to the invention acting perpendicularly or orthogonally to the operating surface.

[0016] In a particularly advantageous manner, the pad can be arranged in the immediate vicinity of the brake lever, so that the operating movements of the person when carrying out the measuring method correspond substantially to the operating movements of a completely normal operation of the parking brake. In contrast, a pad arranged at a greater distance from the brake lever leads to unusual operating movements which can significantly influence the measuring result. The greater the change in geometry caused by such a distance between the pad and the brake lever on the handle of the brake lever compared to conventional brake lever geometries, the greater the undesirable influence or error on the achievable measuring result expected with said brake lever geometry.

[0017] The force sensor for measuring the actuation force component acting orthogonally to the operating surface is preferably arranged between the inner side of the pad facing the handle and the underside of the handle so that a very small distance between the pad and the handle of the brake lever can be achieved.

[0018] It will also be appreciated that the operating surface is substantially defined by the pad, through which the person preferably applies the entire actuation force required to operate the parking brake to the handle of the brake lever. If said operating surface extends substantially perpendicularly to a pivot plane defined by the pivoting movement of the brake lever, the component of the actuation force measured by the force sensor and acting orthogonally to the operating surface has a force action direction extending in the pivot plane or at least parallel to the pivot plane.

[0019] According to a further advantageous embodiment disclosed herein, the effective actuation force at the reference point is determined from the measured actuation force components taking into account the respective positions of the force sensors and the position of the reference point according to the current actuation angle and from the position of the lever pivot axis relative to a reference coordinate system. In this respect, in a further preferred embodiment, the coordinate origin of the reference coordinate system can be specified for describing the positions and for determining the effective actuation force from the actuation force components in the pivot plane of the brake lever, whereby if it can be assumed that all previously mentioned positions lie substantially in the pivot plane of the brake lever, the three-dimensional description of the further positions can be reduced to a two-dimensional view to simplify the determination of the effective actuation force, in particular if for example the reference point of the effective actuation force to be determined is also determined to lie substantially in the pivot plane of the brake lever.

[0020] A further advantageous embodiment disclosed herein provides for determining the effective actuation force at least for a static pivot angle of the brake lever. The static pivot angle here refers to an actuation angle of the brake lever which is determined by a stable static position of the brake lever in which the brake lever can be fixed or locked without actuation forces continuing to be applied on the brake lever. According to this definition, at least one static position of the brake lever is reached after actuation (upward pivoting) of the parking brake and is therefore different from the above-mentioned initial position of the brake lever in which the actuation angle assumes a zero value. Determining at least one static position of the brake lever advantageously enables determining the effective actuation force associated with said static position and can, for example, be used as a uniquely defined comparison value for testing legal provisions and / or for comparing a plurality of parking brakes of identical design.

[0021] According to a further advantageous embodiment disclosed herein, the fixing or locking of the brake lever in at least one static position thereof is caused by a ratchet and pawl arrangement. Ratchet and pawl arrangements of this type are well known, wherein, due to the operation of the parking brake by a person, i.e. due to the pivoting movement of the brake lever, the pawl and at least one ratchet of the ratchet collar are moved relative to each other in such a way that they hold or lock the brake lever in at least one static position by interaction, i.e. they prevent the brake lever from pivoting back into its initial position. According to said embodiment, the ratchet and pawl arrangement exceeds a static pivoting angle determined by the at least one static position into a locking interaction, which locking interaction is necessary to enable the detection of the brake lever in the static position only after an operation of the brake lever.

[0022] This embodiment of the method according to the invention provides that during actuation of the parking brake at a plurality of different operating pivot angles, the effective actuation force is determined and stored at each increment of the pivot angle, the brake lever is pivoted beyond at least one static pivot angle until the ratchet and pawl arrangement enters engagement in a static position associated with the static pivot angle, and then no actuation force component is applied to the brake lever within a predictable static period so that the brake lever adopts its static position at the corresponding static pivot angle, and the effective actuation force is determined at the corresponding static position using a constant operating pivot angle determined within the static period, the constant operating pivot angle corresponding to the static pivot angle previously stored for the actuation angle. In other words, with the embodiment, reaching a defined static position of the brake lever is automatically detected and the effective actuation force in the static position at the corresponding static pivot angle is automatically determined from previously recorded measured values. Thus, the method according to the invention can be used to perform force measurements for different types of parking brakes in a simple manner without requiring a great deal of prior effort. For example, different types of parking brakes can have a different number of defined static positions and / or different angular distances of static pivot angles between the individual static positions.

[0023] The additional operating angle that the brake lever must be operated beyond the actual static pivot angle until the ratchet and pawl arrangement enters into locking engagement in the corresponding static position of the brake lever may be, for example, about 0.2 to 0.5 degrees (angle difference).

[0024] The determination and storage of the effective actuation force at different actuation pivot angles during the actuation of the brake lever is preferably carried out within such short time intervals (measurement intervals) that a sufficiently accurate determination of the effective actuation force at the static pivot angle in the static position of the brake lever is possible. The smaller the measurement interval is chosen, the greater the expected accuracy of the determination of the effective actuation force at the static pivot angle.

[0025] According to a further aspect disclosed herein, a device or apparatus for determining a single or effective actuation force at a reference point applied by a person during actuation of a brake lever comprises a body that can be attached to a handle of a brake lever, the lever being supported for pivoting movement about a pivot axis of a mechanical parking brake of a vehicle when the parking brake is operated via a defined operating surface on the handle of the brake lever. At least two force sensors are mounted on the body and are arranged spaced apart from one another so that the force sensors are at different distances from the lever pivot axis when the body is attached to the handle of the brake lever. The operating force components measured by the force sensors act on the force sensors orthogonally to the operating surface in each case, and the at least two force components are used to determine the effective force when the parking brake is operated by a person.

[0026] With regard to device-related terms and actions and advantages corresponding to features of the device, reference is hereby made to the previous description of the corresponding definitions, actions and advantages of the disclosed method. The disclosures here about the measuring method according to the invention should be applicable in a corresponding manner to the definition of the measuring device according to the invention, if not expressly excluded here. Likewise, the disclosures here about the measuring device according to the invention should be applicable in a corresponding manner to the definition of the measuring method according to the invention, if not expressly excluded here. In this respect, omitting the repetition of a description of this type facilitates a more compact description.

[0027] According to an advantageous embodiment disclosed herein, the device further comprises a pad, which is supported on the body and is arranged on the underside of the brake lever handle when the body is attached to the brake lever. The pad is connected to the force sensor in a force-transmitting manner and provides an operating surface, on which an actuation force component is applied when the parking brake is actuated / operated. For a particularly smooth and appropriate force transmission from the hand of the person operating the brake lever to the brake lever, the pad can preferably have a length which corresponds approximately to the width of an average human hand. Thus, during operation of the parking brake, the pad can be gripped well and evenly.

[0028] Due to the arrangement of the force sensors at different distances from the lever pivot axis, actuation force components which are unevenly distributed and act on the pad orthogonally to the operating surface over its length and which, due to different effective levers or torque arms relative to the lever pivot axis, thus generate different torques on the brake lever can nevertheless be measured accurately, so that the effective actuation force thus determined at the reference point fluctuates only slightly for different test measurements.

[0029] In a further particularly advantageous manner, the pad can be arranged in the immediate vicinity of the brake lever so that the operating movements of the person when carrying out the previously described method according to the invention correspond substantially to operating movements of a completely normal movement for operating the parking brake. The force sensor is preferably arranged between the inner side of the pad facing the handle and the underside of the lever handle so that a very small distance between the pad and the handle of the brake lever can be achieved.

[0030] According to a further advantageous disclosed embodiment, the device further comprises an angle sensor which is operable to measure the actuation angle of the brake lever when the lever is pivoted to apply the parking brake. In principle, the angle sensor can be arranged at any point, for example on the pivot axis of the brake lever, starting from the initial position of the brake lever (actuation angle equal to zero) if an accurate detection of the operating pivot angle is ensured during operation of the parking brake by a person.

[0031] According to a further advantageous embodiment, the angle sensor is fixedly connected or attached to the body. In this way, a particularly compact design of the device for determining the effective actuation force can be achieved, which also only requires a low cost for mounting on the brake lever. Therefore, a device of this type is particularly suitable for performing force measurements on brake levers that are already installed in a vehicle.

[0032] In a further particularly preferred embodiment of the device, the angle sensor is operable to also measure the tilt angle about the longitudinal axis of the body in addition to the actuation angle of the brake lever. The longitudinal axis of the body is determined by its longitudinal extent, wherein the body is advantageously substantially adapted to the shape of the handle of the brake lever. Therefore, a particularly preferred form of the body is embodied as substantially hollow cylindrical, conical or cup-shaped, so that the body can be stably mounted on a conventional substantially cylindrical brake lever handle. In this case, the longitudinal axis of the body substantially corresponds to the central axis of the corresponding hollow cylinder or cone.

[0033] By measuring the inclination angle about the longitudinal axis of the body, an accurately defined orientation of the body (or the entire device) relative to the brake lever handle in its circumferential direction is possible. In this way, it can be ensured that when the device is mounted on the brake lever handle, the force sensor and / or the pad can always be arranged in an orientation relative to the brake lever so that the force sensor can always measure the entire actuation force component acting orthogonally to the operating surface, thus in particular those forces having a force action direction parallel to the pivot plane defined by the pivoting movement of the brake lever, and not forces or force components inclined relative to said pivot plane (lateral forces / lateral force components), since said forces / lateral force components do not contribute to generating a torque on the brake lever about the lever pivot axis. An angle sensor implemented in this way can also be referred to as a three-dimensional angle sensor that can measure angles relative to at least two rotation axes. The measurement and analysis of the inclination angle, for example before or during the force measurement, prevents the undesirable use of the device for determining the effective actuation force on the brake lever, which leads to inaccurate force measurements, and thus further increases the measurement quality that can be achieved with the device according to the invention.

[0034] A further advantageous embodiment of the invention provides an electronic unit, in particular an electronic computing and storage unit, operable to perform the applicable steps of the method according to any of the embodiments described herein. It should be understood that, depending on the specific embodiment of the method to be performed for determining the effective actuation force, the electronic unit is electronically connected to a corresponding force sensor and / or at least one corresponding angle sensor for transmitting corresponding measurement data for subsequent analysis.

[0035] Other features and advantages of the present invention result from the following description of exemplary embodiments of the present invention, which should not be considered as limiting, and which are described in detail below with reference to the accompanying drawings. In the drawings: BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 schematically shows a perspective view of an exemplary embodiment of a device according to the invention;

[0037] Figure 2 Schematically shows the Figure 1 A perspective exploded view of the device;

[0038] Figure 3 Schematic diagram of a brake lever attached to a mechanical parking brake of a vehicle. Figure 1 A side view of the device;

[0039] Figure 4 Schematically shows Figure 3 A side cross-sectional view of the device along its central longitudinal plane;

[0040] Figure 5schematically illustrates an actuation force profile versus time and an actuation angle profile versus time when performing an exemplary embodiment of the disclosed method; and

[0041] Figure 6 Schematically shows the Figure 5 An enlarged cross-sectional view of the curve. DETAILED DESCRIPTION

[0042] As specified, detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the present invention, which may be implemented in various alternative forms. The drawings are not necessarily drawn to scale; certain features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0043] In the various figures, components which are equivalent in their function are always provided with the same reference symbols, so that generally identical components are also described only once.

[0044] Let's describe it together Figures 1 to 3 . Figure 1 shows a perspective view of an exemplary embodiment of a device 1 according to the invention, Figure 2 Shows Figure 1 A perspective exploded view of the device 1 and Figure 3 The vehicle (also not shown) is shown Figure 3 The arrangement of the brake lever 2 of the parking brake, which is not shown in detail, and the attachment to the brake lever 2 Figure 1 A side view of the device 1 is shown. Figure 3 By way of example, the brake lever 2 is shown in its initial position, in which the actuation angle α assumes the value zero.

[0045] The apparatus 1 is used to determine a single, combined or resultant effective actuation force F applied at a specified reference point 3, wherein the effective force F is the force required to be applied by a person (not shown) to actuate the brake lever 2 from a lowered position (corresponding to an OFF state of the parking brake) to a raised position (corresponding to an ON or SET state on the parking brake). As is well known in the art, the brake lever 2 is of a type that is supported for pivotal movement about a lever pivot axis 4 when the parking brake is operated by pulling upward on a handle 5 of the brake lever 2. The handle 5 may refer to a section or portion of the brake lever 2 that a person operating the brakes typically grasps with their hand in order to pull upward to pivot the lever about the axis 4 to apply the parking brake.

[0046] The device 1 comprises a main body 6, such as Figure 3As shown, the body 6 is attached to the handle 5 of the brake lever 2. The body 6 is preferably adapted to the shape of the handle 5 and in the case of the exemplary embodiment shown comprises a substantially half-cup or concave shape, such as Figure 2 Due to its extended extent, the body 6 thus defines a longitudinal axis 7 (eg Figure 3 As shown), the longitudinal axis 7 extends substantially in the direction of the longitudinal extent of the handle 5 of the brake lever 2 when the body 6 is mounted on the handle 5 of the brake lever 2.

[0047] In the exemplary embodiment of the device 1 described, the body 6 is operatively attached or mounted on and thus covers at least the underside of the brake lever handle 5. The device 1 can thereby be securely and stably held on the handle 5 of the brake lever 2.

[0048] For further fastening to the handle 5, the device 1 comprises front and rear mounting brackets 8 which overlap the top side of the handle 5 when the device 1 is mounted on the brake lever 2. The brackets can be reversibly connected to the body 6 by suitable connecting means, such as bolts 9. In this way, a simple fixing of the device 1 to the brake lever handle 5 is achieved, which can also be easily adapted to handles 5 of different shapes or sizes of different brake levers 2 (e.g. handles 5 with different diameters, etc.).

[0049] from Figures 1 to 3 It can also be seen in the figure that in the exemplary embodiment of the device 1 shown, two force sensors 10 and 11 are mounted on the body 6. The sensors 10, 11 can be implemented by known strain gauges and can be substantially identical, in particular with regard to their design, their operating principle and their dimensions. However, this commonality is not absolutely necessary. It can also be seen that the two force sensors 10, 11 are arranged spaced apart from each other along the longitudinal axis 7 so that the force sensors are located at different respective distances 12, 13 from the lever pivot axis 4 after the body 6 is attached to the handle 5. In particular, in this case, the first or forward force sensor 10 is spaced apart from the second or rear force sensor 11 in the longitudinal direction of the body 6, i.e. along the longitudinal axis 7. The distance between the two force sensors 10, 11 is selected to be large enough to achieve a sufficient separation of the two partial actuation force measurements, so as to achieve a significant improvement in the measurement quality of the effective actuation force F at the reference point 3 determined or calculated thereby. In the case of the exemplary embodiment of the device 1 shown, the distance between the two force sensors 10, 11 in the longitudinal direction 7 of the body 6 is preferably about 56.5 mm and can preferably be specified in the range between about 50 mm and about 60 mm. The two force sensors 10, 11 are arranged on the body 6 so that when a person is operating (pulling upwards) the parking brake lever, the sensors measure the corresponding operating force components F1, F2, wherein the force components are used to determine the effective actuation force F at the reference point 3.

[0050] The exemplary embodiment of the device 1 shown further comprises a pad 14 which is supported on the body 6 and provides an operating surface 15 and is connected in a force-transmitting manner to the force sensors 10, 11. Since the body 6 is arranged on the underside of the handle 5 after it is attached to the brake lever 2, the pad 14 is appropriately arranged on the underside of the handle 5 after installation. When a person operates the parking brake by pulling the operating surface 15 upwards with their fingers, the actuation force components F1, F2 measured by the respective force sensors 10, 11 are applied to the pad 14. For an ergonomic transmission of forces between a hand (not shown) and the pad 14, the operating surface 15 may advantageously comprise a wavy shape to define a "finger groove" for positioning a suitable finger of the hand operating the brake lever 2. However, this is not absolutely necessary.

[0051] Regardless of the wavy shape of the operating surface 15, the two force sensors 10, 11 are implemented and arranged to detect only the force components F1 and F2 acting substantially orthogonally to the operating surface 15, such as Figure 3 Only the forces F1, F2 directed perpendicularly to the operating surface 15 generate a torque on the brake lever 2 relative to its pivot axis 4. The two force sensors 10, 11 formed by corresponding strain gauges are also correspondingly embodied to measure only the actuation force components F1, F2 acting perpendicularly or orthogonally to the operating surface 15 on the force sensors 10, 11.

[0052] In the exemplary embodiment of the device 1 shown, the force sensors 10, 11 are mounted on an intermediate plate 16 (see FIG. 1 ) between the inner (upwardly facing or handle-facing) side of the insert pad 14 and the underside of the handle 5. Figure 2 ) which forms or implements a force transmission connection between the pad 14 and the corresponding force sensor 10, 11 so that the actuation force component F1, F2 applied to the device 1 or the pad 14 by the operator through the operating surface 15 is transmitted to the force sensor 10 or 11.

[0053] from Figures 1 to 3 As can also be seen in FIG. 1 , the device 1 shown further comprises an angle sensor 17 which is operable to measure the actuation angle α of the brake lever 2 when the parking brake is operated and the tilt angle of the device 1 about the longitudinal axis 7 of the body 6. The actuation angle α corresponds to the angle by which the lever 2 moves relative to its initial parking brake OFF position. The actuation angle α is measured in the XZ-pivot plane of the brake lever 2, which is defined by the pivoting movement of the brake lever 2 about the pivot axis 4. In contrast, the tilt angle of the device 1 is measured in the YZ plane and indicates the angular position of the device 1 in the circumferential direction of the handle 5 after mounting the device 1 on the brake lever 2. The angle sensor 17 can therefore be referred to as a three-dimensional angle sensor, since it can measure at least two angles relative to different rotation axes (here: the Y axis for the actuation angle α or the X axis for the tilt angle).

[0054] from Figures 1 to 3 As can be seen in the figure, the angle sensor 17 of the device 1 is shown by means of Figure 2 1 is fixedly connected to the body 6 of the device 1. In particular, the angle sensor 17 of the device 1 is arranged diametrically opposite the force sensors 10, 11 or the pad 14 on the opposite side (top) of the body 6. The vertical orientation of the device 1 on the handle 5 can be checked in a particularly simple manner after assembly and / or even during the measurement. The vertical orientation of the device 1 relative to the brake lever 2 refers to an orientation in which the force sensors 10, 11 are arranged substantially vertically below the handle 5, so that the full magnitude of the actuation force component F1, F2 applied perpendicularly to the operating surface 15 of the pad 14 when the parking brake is operated can be detected by the force sensors 10, 11, which, as already mentioned herein, only measure forces acting perpendicularly to the operating surface 15.

[0055] exist Figure 3 The well-known ratchet and pawl arrangement 19 can also be partially seen, which essentially comprises a pawl 20 and a ratchet collar 21 with a plurality of ratchet teeth 22. As the parking brake is operated by a person, i.e. as a result of the pivoting movement of the brake lever 2 (e.g. Figure 3 The actuation angle α is increased by increasing the actuation angle α by rotating the brake lever 2 (in the clockwise direction in FIG. 1 ), so the pawl 20 and the ratchet teeth 22 of the pawl collar 21 move relative to each other. That is, the pawl 20 moves together with the brake lever 2 and the ratchet collar 21 is stationary relative to the brake lever 2, and the ratchet and pawl device is engaged in a static position (α>0) of the brake lever 2 defined by the ratchet teeth 22 of the ratchet collar 21. In the static position, the brake lever 2 is held or locked by the ratchet and pawl device 19, even if no actuation force is applied to the brake lever 2 by the person operating the brake lever 2.

[0056] By reapplying a suitably large actuation force to the handle 5, the brake lever 2 can be pivoted from the static position in the direction of increasing the actuation angle α to the next static position at any time. However, from the static position in the direction of decreasing the actuation angle α (i.e. toward the initial position (α=0) of the brake lever 2) backward and downward (counterclockwise, such as Figure 3 The pivoting of the brake lever 2 (as shown) can only take place after operating a release button 23 which is accessible on the front face of the brake lever 2. The release button 23 projects from the front face of the brake lever 2 in its unactuated position and is pressed towards the rear face of the brake lever 2 or along the longitudinal axis 7 in order to disengage the locking engagement of the ratchet and pawl arrangement 19, which also corresponds to Figure 3 The axis of symmetry of the release button 23 of the brake lever 2 is shown in FIG.

[0057] In order to correctly and precisely position the device 1 on the brake lever 2, the device 1 may further comprise an end stop 24. In the exemplary embodiment of the device 1 shown, said end stop is mounted on the body 6 and is adjustable relative thereto in its height, i.e. perpendicularly to the longitudinal axis 7. In this way, the end stop 24 can be adjusted so that when mounted on the handle 5 it can come into contact with the point of the end face of the brake lever 2 which extends furthest forward from the handle 5 without being hindered by the release button 23, so that the body 6 of the device 1 and therefore the force sensors 10, 11 are always and reproducibly arranged in a precisely defined position relative to the handle 5.

[0058] In the example shown, the reference point 3 (also called force application reference point) chosen for measuring the individual or combined actuation forces F is designated at a distance 25 of about 40 mm along the longitudinal axis or axis of symmetry 7 of the release button 23 from the point of the end face of the brake lever 2 where the end stop 24 comes into contact with the handle 5 after assembly of the device 1. This is however not absolutely necessary and it may also be designated at another point.

[0059] Figure 3 Further shown is an electronic unit 26, in particular an electronic calculation (e.g. a microprocessor) and storage unit, operable to carry out the relevant steps of the method described herein for determining the effective actuation force F. To this end, the electronic unit 26 is connected to the force sensors 10, 11 and to the angle sensor 17 via suitable electrical connections in order to receive the measured values ​​during the force and angle measurement and to analyse the measured values ​​in the context of the present invention, in particular to determine, for example, a single effective actuation force F from the actuation force components F1 and F2. Figure 3 In the case of the exemplary embodiment shown, the electrical connection between the control unit 26 and the device 1 is effected via a connecting line via a suitable connector formed on the angle sensor 17 .

[0060] Figure 4 Schematically shows Figure 3 2 is a highly simplified side sectional view of the device along its central longitudinal plane, which corresponds here to the pivot plane of the brake lever 2. Figure 4 It is shown that the effective actuation force F at the reference point 3 is determined from the measured force components F1, F2 as a function of the current actuation angle α and from the position 30 of the lever pivot axis 4 while taking into account the corresponding positions 27, 28 of the force sensors 10, 11 and the position 29 of the reference point 3. In this case, the positions 27, 28, 29 and 30 are each understood as a vector starting from the coordinate origin of an XZ reference coordinate system. Advantageously, in the case of the exemplary embodiment shown here, said reference coordinate system is a two-dimensional coordinate system (y=0), since it can be assumed that all positions 27, 28, 29 and 30 are located substantially in the pivot plane of the brake lever 2.

[0061] Due to the precise arrangement / positioning of the device 1 on the handle 5 of the brake lever 2 using the end stop 24 already described, a precise and correct position of the positions 27, 28 and 29 relative to each other and to the handle 5 of the brake lever 2 is always ensured even on brake levers of different designs.

[0062] The effective actuating force F acting at the reference point 3 can be determined by using appropriate vector geometry and a torque balance from actuating force components F1 and F2 acting orthogonally to the operating surface 15 and measured by the force sensor 10, as well as unique geometric information or positions 27, 28, 29 and 30 (i.e., the positions of the first force sensor 10, the second force sensor 11, the reference point 3 and the rod pivot axis 4).

[0063] In a particularly advantageous manner, the geometrical information, namely the positions 27 , 28 , 29 and 30 , can be easily determined or read out from a CAD model of the arrangement of the brake lever 2 and the device 1 .

[0064] According to the torque balance applicable at each actuation angle α

[0065] ∑M=0

[0066] We get

[0067] -F1*R1–F2*R2+F*R=0

[0068] And further

[0069] F=(F1*R1+F2*R2) / R

[0070] Where R1 corresponds to the length of the effective torque arm relative to the operating force component F1 measured by the force sensor 10 and acting orthogonally to the operating surface 15 (right angle between F1 and R1), R2 corresponds to the length of the effective torque arm relative to the operating force component F2 acting orthogonally to the operating surface 15 and measured by the force sensor 11 (right angle between F2 and R2), and R corresponds to the length of the effective torque arm relative to the effective actuation force F determined at the reference point 3 (right angle between F and R). The effective torque arm R is the shortest connection between the pivot axis 4 and the reference point 3. The respective lengths of the effective torque arms R1, R2 and R are all measured from the lever pivot axis 4.

[0071] It will be appreciated that further forces may be calculated from the previously determined effective actuation force F using known vector geometry, thus for example the (maximum) total actuation force F' acting on the underside of the pad 14 or on the operating surface 15:

[0072] F′=F / cos(β)

[0073] Where β corresponds to the angle enclosed by the force action direction of the effective actuation force F together with the force action direction of the operating force component F1 or F2 acting orthogonally to the operating surface 15. Of course, forces in other force action directions may also be calculated optionally, the determination of which is based on calculations using the known positions 27, 28, 29 and 30.

[0074] Likewise, all other geometric intermediate variables required for the previous calculations (such as the distance between the two force sensors 10 , 11 , the length of the effective torque arms R1 , R2 and R, the inclination angle β, etc.) can be determined from the known positions 27 , 28 , 29 and 30 using vector geometry.

[0075] Figure 5 An actuation force profile 31 over time of an effective actuation force F determined for a reference point 3 and an actuation angle profile 32 over time of an operating pivot angle α detected by the angle sensor 17 are shown when an exemplary embodiment of a method for determining an effective actuation force F according to the invention is performed. The electronic unit 26 is operable to generate a graph 31 by correlating the measured values ​​or readings from the effective actuation force F (from the force sensors 10, 11) and the angle α (from the angle sensor 17). Figure 5 The relationship shown in .

[0076] from Figure 5 It can be seen that a total of six static positions or static pivot angles α1, α2, α3, α4, α5 and α6 are determined by the ratchet and pawl arrangement 19, wherein α0 corresponds to the initial position of the brake lever 2 (brake OFF) and therefore assumes the value zero.

[0077] from Figure 5 As can be seen in FIG. 1 , when using the device 1 to perform the method according to the invention, the brake lever 2 is initially carefully pulled upwards from the initial position α0 (i.e. in particular at a sufficiently low angular velocity) until the brake lever 2 can be fixed (i.e. locked) in the first static position or at the first static pivot angle α1 by the ratchet and pawl device 19. Once the brake lever 2 is locked in the first static position (static pivot angle α1), the person can release the brake lever 2 so that no upward actuation force is now applied to the brake lever 2. The brake lever 2 is not operated for the static period Δt. The previous steps are then repeated so that the static positions of the remaining static pivot angles α2, α3, α4, α5 and α6 are successively reached. In the final static position (static pivot angle α6), the movement of the brake lever 2 can be limited by the brake lever end stop or the maximum permissible actuation force can be achieved.

[0078] Figure 6 Shown is the dashed line bounded Figure 5. It can be seen how the effective actuating force F increases with increasing operating angle α when the brake lever 2 is pivoted from the static pivot angle α1 (first static position) to the static pivot angle α2 (second static position). As already described herein, the ratchet and pawl arrangement 19 does not enter into locking engagement directly when the static pivot angle α2 is reached, but only after the brake lever 2 has been pivoted slightly by a person beyond said static pivot angle α2. The necessary "overshoot" (additional operating angle) also requires a corresponding additional actuating force, whereby the maximum effective actuating force Fmax determined in the case of an overshoot also exceeds the actual effective actuating force at the corresponding static pivot angle α2. The additional angle can, for example, be of the order of 0.2 to 0.5 degrees. The overshoot of the operating pivot angle α and the actuating force F is in the range of 0.2 to 0.5 degrees. Figure 6 In the figure, they are indicated by reference numerals 33 and 34.

[0079] When the method shown is carried out, i.e. during actuation (upward pivoting) of the brake lever 2 by a person, a plurality of actuation angles α measured over time are acquired and stored by the electronic unit 26. Likewise, the effective actuation force F determined at the actuation pivot angle α is acquired and stored by the electronic unit 26. After the overshoot of the brake lever 2 beyond the static pivot angle α2, the brake lever 2 is released within a static period Δt, so that the brake lever 2 moves back into the second locked static position and there adopts the static pivot angle α2. Figure 6 It can be seen from FIG. 5 that during the static period Δt, the effective actuation force F returns to a zero value.

[0080] Due to the static period Δt (which may preferably last approximately 1 to 5 seconds, or more preferably approximately 2 to 3 seconds, and in the case of the illustrated exemplary embodiment of the measuring method approximately 2 seconds), the electronic unit 26 detects a constant, unchanging actuation angle α, which corresponds here to the static pivot angle α2. Based on the effective force value F previously stored at the actuated pivot angle α, the control unit 26 now determines the effective force value Fα2 associated with the previous first arrival at the static pivot angle α2, as Figure 6 In this way, the exact effective actuation force F at the reference point 3 can be determined at a specified static pivot angle α2. The same procedure is used at all other static pivot angles α1-α6.

[0081] At this point it should be noted that when carrying out the previously described method for holding the vehicle at a certain vehicle inclination, the actuation angle overshoot 33 and the actuation force overshoot 34 should be smaller than a defined value, since the determination of the effective actuation force F may otherwise be the result of an error due to the hysteresis effect of the parking brake. If, for example, the actuation force overshoot 34 is too large, the effective actuation force F determined as above when using the effective actuation force F (e.g. Fα2) of the brake lever 2 determined in the corresponding locked static position (e.g. at α2) is set too low when holding the vehicle at an angle. On the other hand, if the maximum determined effective actuation force Fmax associated with the corresponding static position during the actuation force overshoot 34 is to be used, the effective actuation force determined for the locked static position will be set too high.

[0082] By using the device according to the invention described herein for determining an effective actuating force and the method described herein for determining an effective actuating force, in particular the following causes of error can be avoided in a particularly advantageous manner:

[0083] The falsification of the results is achieved by measuring the actuation force applied by the person operating the brake lever 2 not perpendicularly to the grip 5 of the brake lever 2 .

[0084] Falsification of the measurement results due to the distribution of the actuation force over the width of the operator's hand, which can be different for different people in particular. For example, the actuation force input can be performed more via the front part of the finger or more via the back part of the finger, which results in different effective levers or torque arms and thus in different measured effective actuation forces.

[0085] The falsification of the measurement results is caused by the force overshoot to reach the locked static position when the maximum actuation force determined during this period (Fmax) is used, which leads to the setting of an actuation force that is too large for the static position.

[0086] Falsification of the measurement result due to the fact that the measuring device or force sensor is not arranged perpendicularly to the grip of the brake lever, since an additional lateral actuation force component is thereby generated which is not used for effective actuation of the brake lever. The actuation force F is therefore measured to be too large.

[0087] Falsification of the measurement result due to the arrangement of the measuring device and thus the force sensor too far forward or backward on the grip of the brake lever, which also leads to a different effective lever or torque arm and thus to a different measured actuation force F.

[0088] The method according to the invention and the device according to the invention described above are not limited to the embodiments disclosed here, but in each case also include further embodiments which function in the same way.

[0089] In a preferred embodiment, the device according to the invention is used to determine a single effective actuation force at a reference point when a person operates a manually operated mechanical parking brake of a vehicle, in particular a motor vehicle, via a brake lever.

[0090] Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the present invention. On the contrary, the words used in the specification are descriptive rather than restrictive, and it should be understood that various changes can be made without departing from the spirit and scope of the present invention. In addition, the features of various implementation embodiments can be combined to form other embodiments of the present invention.

Claims

1. A device for measuring the actuation force of a parking brake, comprising: a body adapted to be mounted to a lever that is manually pivotable about an axis by a person to apply the parking brake of a motor vehicle; first and second force sensors, the first and second force sensors each disposed on the body at respective first and second distances from a pivot axis of the lever when the body is mounted to the lever, the force sensors being operable to measure a force applied to a lower surface of the lever to cause the lever to pivot; an angle sensor disposed on the body and operable to measure an actuation angle of pivoting of the lever about the pivot axis during application of the parking brake; as well as An electronic unit is operable to read the respective first and second forces applied to the force sensor during pivoting of the lever, thereby calculating an effective actuation force applied at a reference point on the lever, and to relate the effective actuation force to the actuation angle.

2. The device according to claim 1 further comprises a pad, which is supported on the body so that, when the body is mounted to the rod, the pad is arranged on the underside of the rod and is connected to the force sensor in a force-transmitting manner, and the pad provides a surface on which the first and second force components are applied to actuate the rod.

3. The apparatus of claim 1, wherein the angle sensor is further operable to measure an angle of inclination about a longitudinal axis of the rod.

4. A device for measuring the actuation force of a parking brake, comprising: a body adapted to be mounted to a lever that is pivotable about an axis to actuate a vehicle parking brake; first and second force sensors disposed on the body at respective first and second distances from a pivot axis of the lever when the body is mounted to the lever; and an electronic unit for reading the respective first and second forces applied to the force sensor during actuation of the rod and calculating therefrom the effective actuation force applied at a reference point on the rod; Further included is an angle sensor operable to measure an actuation angle of pivoting of the lever about the pivot axis.

5. The device according to claim 4 further comprises a pad, which is supported on the body and is arranged on the underside of the rod when the body is mounted to the rod and is connected to the force sensor in a force-transmitting manner, and the pad provides a surface, and the first and second force components are applied to the surface to actuate the rod.

6. The apparatus of claim 5, wherein the angle sensor is further operable to measure an angle of inclination about a longitudinal axis of the rod.

7. A device for measuring the actuation force of a parking brake, comprising: a body attachable to a vehicle parking brake lever pivotable about an axis; first and second force sensors disposed on the body at respective first and second distances from a pivot axis of the lever when attached to the lever; and an electronic unit for reading the first and second force components applied to the respective force sensors to rotate / pivot the lever and calculating therefrom the effective actuation force applied at a reference point on the lever; Further included is an angle sensor operable to measure an actuation angle of the lever pivoting about the pivot axis, wherein the angle sensor is further operable to measure an angle of inclination about a longitudinal axis of the lever.

8. The device according to claim 7 further comprises a pad, which is supported on the body and is arranged on the underside of the rod when the body is mounted to the rod and is connected to the force sensor in a force-transmitting manner, and the pad provides a surface, and the first and second force components are applied to the surface to actuate the rod.

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