Title of Invention

PEDAL DISPLACEMENT SENSOR

Abstract

This invention relates to a pedal displacement sensor for determining a pedal displacement comprising at least one actuating lever (38) arranged in a housing (32), the actuating lever (38) is supported on a rotational, axis (36), and rotatable by a pedal (10,12); and at least one switching element (56) having an actuating element (58) which is actuated by rotating the actuating lever (38). The housing (32) contains an opening (44) that makes it possible to gain external access to a region of the actuating lever (38) that lies outside of the rotational axis (36) so as to subject the actuating lever (36) to the influence of a pedal movement, and in that the actuating lever (38) to the influence of a pedal movement, and in that the actuating lever (38) acts upon at least one measurement device (114, 116) for generating an electrical signal that corresponds to the rotational position of the actuating lever (38).

Full Text

PEDAL DISPLACEMENT SENSOR Description The invention pertains to a pedal displacement sensor for determining a pedal displacement The pedal displacement sensor contains at least one actuating lever and at least one switching element. The actuating lever is arranged in a housing, supported on a rotational axis and can be rotated by a pedal The actuating element of the switching element is actuated by rotating the actuating lever. In motor vehicles, it is customary practice to arrange within the region of a pedal one or more electric switches that determine the pedal position and deliver corresponding control signals. For example, an agricultural tractor is provided with a right brake pedal and a left brake pedal that can be operated separately in order to drive through tight curves Each brake pedal acts directly upon one brake cylinder. The trigger element of a brake light switch, which changes over when the pedal is actuated and delivers an electrical signal to the brake light, is arranged within the travel range of each pedal Tn this case, the changeover point is frequently subject to a relatively marked hysteresis that is acceptable for the actuation of brake lights. It would be desirable to make functions of the vehicle other than the brake lights, e.g., the addition of a front wheel drive and the actuation of a differential lock, dependent on the position of the brake pedal. However, these functions make it necessary to adapt the changeover point of the switch to the pedal displacement in a relatively precise fashion. In US-A-5,920,048, it is proposed to determine the position of the accelerator pedal and the brake pedal of an electric vehicle with devices in which an electric switch and an adjustable resistor are arranged in a housing. A shaft that is connected to the accelerator pedal or the brake pedal and turns in accordance with the pedal movement extends through the housing The shaft is connected to a pivoted actuating element that acts upon the switch when the shaft is turned. A wiper that moves over a resistive coating when the shaft is turned is mounted on the actuating element This causes the resistance of an electric circuit to change such that a signal corresponding to the pedal position is generated This device is designed in a relatively complicated fashion because it requires a shaft that is connected to a pedal. Adaptation to existing pedal arrangements may also prove difficult Due to the mechanical brush contacts, this device is also relatively susceptible to defects, and is not very accurate. The invention is based on the objective of disclosing a pedal displacement sensor of the type initially mentioned that eliminates the aforementioned problems The pedal displacement sensor should, in particular, allow a reliable determination of the pedal position with reproducible, largely hysteresis-free switching points as well as a simple installation without requiring adaptation measures and subsequent adjustments, and should have a simple design This object is attained with the features of the invention. Other advantageous embodiments and additional developments of the invention are disclosed hereinbelow. According to the invention, the housing of the pedal displacement sensor initially mentioned contains an opening that makes it possible to gain external access to a region of the actuating lever that lies outside the rotational axis so as to subject the actuating lever to the influence of a pedal movement. This means that the pedal acts directly upon the pivoted actuating lever, i.e. without intermediate components such as shafts, levers and the like. The pivoted arrangement of the actuating lever is particularly advantageous because the risk of jamming or seizing is, in contrast to linear movements, significantly reduced Hysteresis effects are largely avoided due to this measure. Consequently, the pedal displacement sensor can be separately manufactured in the form of a simple preadjusted component and can be mounted in the vicinity of the pedal lever with simple means, e.g. screw connections., without requiring adaption measures and subsequent adjustments. Special precautions for the transmission of power between the pedal lever and the actuating lever of the pedal displacement sensors are not required. It is particularly advantageous to realize the actuating lever in the form of an angle lever, with the end of the first arm being rotatably supported in the housing . The end region of the second arm of the lever projects out of the opening in the housing with its enf face. The pedal lever makes contact with the end face of this arm, with the pedal force acting essentially perpendicularly upon the end face and turning the angle lever about its rotational axis . The two arms of the angle lever may, for example, form an angle of approximately 90° . The design in the form an angle lever also provides the advantage that only a relatively small opening for the end of the second arm needs to be arranged in the housing because this arm end does not perform a substantial transvers movement relative to the opening in the housing. The housing is preferably realized in a compact and stable fashion. The housing walls in particular, the lead-throughs for electrical lines, are hermetically sealed such that environmental influences, e.g. dust and splash water, do not impair the function of the pedal displacement sensor. Within the region of the opening in the housing, the housing is sealed relative to the actuating lever, in particular, relative to the end of its second arm, by a flexible rubber collar. The actuating element of the switching element is preferably arranged in the vicinity of the bend of the angle lever and lies approximately opposite to the end face of the second arm. The greatest excursion of the angle lever occurs in the vicinity of the bend, such that the switching element is able to respond to actuations of the pedal lever in a relatively precise fashion. The switching element preferably consists of a microswitch with a pushbutton that serves as the actuating element. Suitable microswitches are, for example, distributed under the designation Micro Switch or Miniatur-Basisschalter by the firms Cherry and Honeywell with branch offices in Auerbach/Opf., DF, and Offenbach, DF, respectively These inexpensive mass- produced items can be subjected to mechanical loads and are quite versatile. The peculiarities of these switches are their high switching capacity (e.g., 25 A) and their small structural size (e.g., 30 mm x 20 mm x 10 mm) The entire force exerted upon the actuating lever should be prevented from being transmitted to the actuating element of the switching element to avoid damage to the switching element or variations in its switching point Consequently, one preferred additional development of the invention proposes that the actuating lever does not act directly upon the actuating element. A spring tongue is mounted on the actuating lever, with the free end of said spring tongue acting upon the actuating element of the switching element It is preferred that at least one limit stop be arranged in the travel path of the spring tongue in order to limit its excursion. This limit stop may, for example, be integrated into the contour of the housing A spring presses the actuating lever into a position that corresponds to the position of the depressed pedal (e.g., the braking position), with the actuating element of the switching element not being actuated by the actuating lever in this position The spring that, for example, consists of a helical compression spring, preferably engages in the vicinity of the bend of the actuating lever and presses the actuating lever in the direction opposite to the force occurring during pedal actuation According to one particularly preferred embodiment of the invention, the actuating lever acts upon at least one measurement device in order to generate an electrical signal that corresponds to the rotational position of the actuating lever This means that an analog electrical signal that corresponds to the rotational position of the actuating lever and consequently to the pedal displacement is available, in addition to the switching signal of the switching element. Tt has proved particularly advantageous to utilize at least one Hall sensor and at least one magnet in the measurement device. A measurement device designed in this way operates in a contact-free fashion, contains no brush contacts, and allows reliable determination of measurement values that is largely independent of corrosion and other interfering influences while providing a high degree of measurement accuracy. A Hall sensor responds very sensitively to changes in the magnetic flux, such that even very small angular movements of the actuating lever can be detected The characteristic of the Hall sensor, i.e.. the dependence of the sensor signal on the position of the actuating lever, can be easily adapted to the respective requirements by adapting the electronic Hall sensor components or by programming the evaluation electronics accordingly Consequently; the accuracy with which the Hall sensor and the permanent magnet are mounted need not be subject to strict requirements, because any deviations can be subsequently compensated by means of electrical or electronic adjustments. A permanent magnet that moves with the actuating lever is preferably arranged on the actuating lever, with the Hall sensor being stationarily arranged in the housing within the magnetic field of the permanent magnet. When the permanent magnet is moved due to actuation of the actuating lever the magnetic flux within the region of the Hall sensor and consequently its output signal, are changed According to one preferred additional development of the invention, the permanent magnet is arranged on the actuating lever in the vicinity of its rotational axis, with the permanent magnet being aligned such that a line which connects the magnetic north pole aad the magnetic south pole extends approximately perpendicular to the rotational axis of the actuating lever. Tn order to achieve a largely linear correlation between the pedal position and consequently the rotational position of the actuating lever, on the one hand, and the sensor signal on the other hand, one particularly advantageous arrangement of the Hall sensor is characterized by the fact that the Hall sensor is arranged to be approximately in the mid-plane extending between the magnetic north pole and the magnetic south pole of the permanent magnet. In this arrangement, the permanent magnet moves almost linearly along its north-south alignment past the Hall sensor when the actuating lever is turned. Consequently, the Hall sensor signal is approximately proportional to the rotational position of the permanent magnet and thus is proportional to the excursion of the actuating lever and the pedal displacement. In order to protect the measurement device as well as other electrical components in the sensor housing fiom interference by external magnetic fields, it is expedient to arrange a magnetic shield, e.g., an iron sheet, in the housing. In motor vehicles that in particular, are provided with two brake pedals that can be operated independently of one another, it is advantageous to provide a pedal displacement sensor in which two actuating levers, each of which is subjected to the effect of one brake pedal, are rotatably arranged in a single sealed housing At least one switching element and/or at least one measurement device is/are assigned to each of the two actuating levers. In order to allow a direct evaluation of the signals of the switching elements and measurement devices in the pedal displacement sensor, it may be particularly advantageous to arrange additional electrical or electronic components in the housing of the pedal displacement sensor. In this respect, it is particularly preferred to incorporate one or more relay(s) and/or printed circuit boards with electrical components. Due to these measures, the requirements with respect to the cable harness and the plug connection for connecting the cable harness to the pedal displacement sensor can be reduced. The pedal displacement sensor according to the invention can be advantageously realized in the form of a preassembied module, in which all components that determine the pedal position are accommodated in a hermetically sealed housing. This module may, for example, be manufactured and adjusted such that it is ready for use by a component supplier. Then, during final assembly of the meter vehicle, the module can be installed in the vicinity of the pedal in the form of a unit, without requiring any subsequent adjustments. This modular design also makes it possible to provide different options for different requirements, with the same housing shape and the same design of the actuating level(s). For example, two switches and only one sensor or two switches and one relay or two switches and two sensors or two switches, two sensors and one relay can be arranged in one standard housing with two actuating levers. The pedal displacement sensor according to the invention allows reliable determination of the pedal position with high sensitivity of the measurement device and with reproducible switching points of the switching element. Due to the precise preadjustment, hysteresis effects of the switching elements can not be prevented, it can be reduced or at least reduced. The signal of the measurement device that corresponds to the pedal position may, for example, be used to electronically control the motor vehicle engine or to influence the engine characteristic curve. The invention, as well as other advantages and advantageous additional developments and embodiments of the invention, are described in greater detail below with reference to the figures that show one embodiment of the invention. The figures show: Figure 1, a brake pedal arrangement with two brake pedals; Figure 2, an oblique representation of a pedal displacement sensor according to the invention; Figure 3, a section through a pedal displacement sensor according to the invention; Figure 4, an illustration of an actuating lever, and Figure 5, an electric circuit diagram for a pedal displacement sensor according to the invention The brake pedal arrangement shown in Figure 1 contains two brake pedals 10, 12 which are supported in a pivoted fashion by a rotational axis 14. Each brake pedal 10, 12 acts upon a corresponding brake piston 16 18, with both brake pistons 16. 18 being arranged in a common brake valve housing 20. The brake pedals 10, 12 can be operated independently of one another. However, the brake pedals can also be connected with the aid of a connecting bar 21 in such a way that, when operating one brake pedal 10, 12t the other brake pedal 10, 12 is also actuated, i.e., both brake pistons 16, 18 are actuated simultaneously. Transverse brackets 22, 24 which respectively accommodate one set screw 26, 28 are integrally formed onto the upper free end of each brake pedal 10, 12. The set screws 26, 28 can be turned in order to adjust how far they protrude out of the respective brackets 22, 24. This allows an adaptation to the trigger elements of the pedal displacement sensor. The set screws 26, 28 can be conventionally fixed in their respective positions by means of locknuts, not shown. A pedal displacement sensor 30, which is illustrated in the form of an oblique representation in Figure 2, is attached to the brake valve housing 20 at the height of the brackets 22, 24 by means of two screws. The housing 32 of the pedal displacement sensor consists of a pot-shaped base part 32a and a cover 32b that can be fixed to the base part 32a by means of two screws 34 and hermetically seals the base part 32a with the aid of a seal, not shown. The cover may also be welded to the base part. Two essentially identical actuating levers 38 are supported in the sensor housing 32 such that they can be pivoted about a rotational axis 36, with only one actuating lever being visible in Figure 3. The actuating lever 38 is realized in the form of an angle lever and contains a first arm 40 at the free end region of which the actuating lever 38 is supported such that it can be rotated about a rotational axis 36. The second arm 42 of the angle lever protrudes out of the sensor housing 32 through an opening 44 in the housing. The two arms 40,42 form an angle of nearly 90° For reasons of material savings and weight reduction, the angle lever 38 contains cavities that are not illustrated in detail. In the vicinity of the bend 68, the angle lever contains a recess 50 into which one end of a helical compression spring 52 engages. The other end of this compression spring is braced on an intermediate wall 48 of the sensor housing 32. The compression spring 52 presses the second arm 42 outward through the opening 44 in the sensor housing 32 such that the end face 46 of the second arm 42 makes contact with the corresponding set screw 26, 28. The second arm 42 is aligned such that its center line 49 approximately intersects the center of the end face 46 of the second arm 42 and is directed toward the actuating element 58 of a switching element 56 A flexible rubber collar 54 that seals the sensor housing 32 relative to the second arm 42 of the angle lever 38 is provided within the region of the opening 44 in the housing. However, the rubber collar 54 allows a sufficient movement of the angle lever 38. One microswitch 56 that is mounted in the interior of the housing is respectively assigned to each of the two actuating levers 38, with only one microswitch being invisible in Figure 3. The microswitch 56 contains a pushbutton 58., actuation of which makes it possible to influence the switching state of the microswitch 56. The pushbutton 58 is situated in the vicinity of the bend 68 of the actuating lever 38. Figure 4 shows in greater detail that the actuating lever 38 contains a spring tongue 60 that is integrally formed onto the actuating lever in the vicinity of the rotational axis 36 and essentially extends parallel to the first arm 40. The free end of the spring tongue 60 contains a contact surface 62 that is situated opposite the pushbutton 58 and is pressed against the pushbutton 58- when the corresponding brake pedal 10, 12 is- operated, such that a switching function of the microswitch 56 is triggered. An edge 64 of the housing that limits the excursion of the spring tongue 60 and thus protects the pushbutton 58 from excessively high loads, is situated opposite the free end of the spring tongue 60. The stroke of the actuating lever 38 is limited by an inner housing wall 66, against which the region of the bend 68 impacts during full actuation of the actuating lever 38. This measure also serves to preventing damage The actuating lever 3-8 is realized in a cylindrical fashion within the region of the rotational axis 36. A recess, in which a permanent magnet 114 is arranged, is situated in a cylindrical end section 112 The permanent magnet 114 is arranged in such a way that a line 116 that connects the magnetic north pole N and the magnetic south pole S extends perpendicular to the rotational axis 36. A Hall sensor 118, with electric supply lines 122, is mounted in the sensor housing 32 in the vicinity of the permanent magnet 114 The Hall sensor 118 is arranged approximately in the mid-plane 120 that extends between the magnetic north pole N and the magnetic south pole S of the permanent magnet 114. In addition to the aforementioned components, other not-shown electrical components, e.g., relays and printed circuit boards, may also be accommodated in the sensor housing 32. At least one hermetically sealed lead-through for electric lines, which is not illustrated in greater detail, is situated in the housing wall The lines connect the electrical components in the interior of the sensor housing 32 to the plug contacts of a plug, not shown, that is integrated into the sensor housing 32. A motor vehicle wiring harness can be connected to this plug. The electric circuit shown in Figure 5 that is arranged within the housing 32 of the pedal displacement sensor is indicated in Figure 5 by a broken line 72. The components, which are illustrated in the form of conventional symbols, e.g., switches, Hall sensors, relays, resistors and capacitors, may be mounted on an printed electrical circuit board, not illustrated in greater detail, and arranged in the sensor housing 32. The circuit shown contains two brake pedal switches 74, 76 that correspond to the microswitch 56 shown in Figure 3 and are respectively assigned to one of two brake pedals 10 12. A battery lead 78 of the brake pedal switches 74, 76 is connected to the motor vehicle battery, not shown. In the idle position of the brake pedal switches 74, 76 illustrated, i.e., when the brake pedals 10, 12 are not actuated, the battery lead 78 is connected via the brake pedal switches 74, 76 to a relay 80, the second connection 82 of which is grounded. The relay 80 actuates a switch 84 that connects the battery lead 78 to a brake valve relay 86 assigned to the air pressure brakes of a trailer not shown. When both brake pedal switches 74, 76 change over due to an actuation of the brake pedals 10, 12, the relay 80 drops and changes over the switch 84 such that the battery lead 78 is connected to the brake lights 88 of the motor vehicle and supplies the not—shown brake lights of the trailer with a voltage via a connection 90. When the brake pedals 10, 12 are actuated in the corresponding brake pedal switch 74, 76 delivers a corresponding voltage signal to an electric motor vehicle control, not illustrated in greater detail, via a connection 92,94. This figure also shows two Hall sensors 118, 119 each of which is assigned to one brake pedal 10, 12. The Hall sensors 118, 119 are conventionally equipped with resistors and capacitors and require no additional explanation because a person skilled in the art is familiar with arrangements of the type. The Hall sensors 118, 119 are connected to a 5 V voltage source via a first connection 96 and grounded via a second connection 98. The output lines 100, 102 of the Hall sensor arrangement are connected to a motor vehicle control, not shown, that suitably evaluates the brake pedal position determined by means of the Hall sensors 118, 119. Although the invention has only been described with reference to one embodiment, a person skilled in the art would, in light of the previous description and the figures, be able to realize various alternatives, modifications and variations that fall within the scope of the present invention. We Claim 1. Pedal displacement sensor for determining a pedal displacement comprising at least one actuating lever (38) arranged in a housing (32), the actuating lever (38) is supported on a rotational axis (36), and rotatable by a pedal (10, 12); and at least one switching element (56) having an actuating element (58) which is actuated by rotating the actuating lever (38), characterized in that the housing (32) contains an opening (44) that makes it possible to gain external access to a region of the actuating lever (38) that lies outside of the rotational axis (36) so as to subject the actuating lever (38) to the influence of a pedal movement, and in that the actuating lever (38) acts upon at least one measurement device (114, 118) for generating an electrical signal that corresponds to the rotational position of the actuating lever (38). 2. Pedal displacement sensor as claimed in claim 1, wherein the actuating lever (38) constitutes an angle lever having a first arm end (40) and a second arm end (42), the second arm end (42) comprising an end face (46), and wherein the first arm end (40) rotatably supporting the angle lever (38), the end face (46) of the second arm end (42) projecting out of the opening (44) and being subjected to a pedal force that acts essentially perpendicularly upon the end face (42). 3. Pedal displacement sensor as claimed in claim 1 or 2, wherein the opening (44) in the housing (32) is sealed relative to the actuating lever (38), in particular, relative to the second arm end (42), by means of a flexible rubber coiiar (54). 4. Pedal displacement sensor as claimed in claim 2 or 3, wherein the actuating element (58) of the switching element (56) is disposed adjacent to a bend (68) of the angle lever (38) being opposite to the end face (44) of the second arm end (42). 5. Pedal displacement sensor as claimed in one of claims 1-4, wherein the switching element (56) is realized in the form of a microswitch with a push button (58). 6. Pedal displacement sensor as claimed in one of claims 1-5, wherein a spring tongue (60), the free end of which acts upon the actuating element (58) of the switching element (56), is mounted on the actuating lever (38). 7. Pedal displacement sensor as claimed in claim 6, wherein at least one limit stop (64) for limiting the excursion of the spring tongue (60) is arranged in the travel path of the spring tongue (60). 8. Pedal displacement sensor as claimed in one of claims 1-7, wherein a spring (52) that presses the actuating lever (38) in the direction opposite to that of the force occurring during a pedal actuation bears on the actuating lever (38), in particular, in the region of the bend (68). 9. Pedal displacement sensor as claimed in one of claims 1-8, wherein the measurement device contains at least one Hall sensor (118) and at least one permanent magnet (114). 10.Pedal displacement sensor as claimed in claim 9 and 10, wherein the permanent magnet (114) is arranged on the actuating lever (38), and wherein the Hall sensor (118) is stationary arranged in the housing (32) within the magnetic field of the permanent magnet (114). 11.Pedal displacement sensor as claimed in claim 9 or 10, wherein the permanent magnet (114) is arranged on the actuating lever (38) adjacent to the rotational axis (36) being aligned in such a way that a line (116) connecting the magnetic north pole (N) and the magnetic south pole (S) extends perpendicular to the rotational axis (36). 12.Pedal displacement sensor as claimed in one of claims 10-12, wherein the Hall sensor (118) is arranged in mid-plane (120) that extends between the magnetic north pole (N) and the magnetic south pole (S) of the permanent magnet (114). 13. Pedal displacement sensor as claimed in claims 9 to 12, wherein a magnetic shield for the measurement device (114,118) is arranged in the housing (32). 14.Pedal displacement sensor as claimed in one of claims 1-12, wherein two actuating levers (38) are rotatably supported in the housing (32), said two actuating levers being respectively subjected to the effect of one assigned brake pedal (10,12), and wherein one of at least one switching element (56) and at least one measurement device (114,118) is assigned to each actuating lever (38). 15.Pedal displacement sensor as claimed in one of claims 1-14, wherein one of at least one electrical relay and at least one printed circuit board having electricai components is arranged in the housing (32). 16.Pedal displacement sensor as claimed in one of claims 1-15, wherein the housing (32) is compact, stable and sealed against environmental influences. 17.Pedal displacement sensor as claimed in one of claims 1-16, wherein the pedal displacement sensor is configured in the form of a preassembled module. This invention relates to a pedal displacement sensor for determining a pedal displacement comprising at least one actuating lever (38) arranged in a housing (32), the actuating lever (38) is supported on a rotational axis (36) and rotatable by a pedal (10, 12)) and at least one switching element (56) having an actuating element (58) which is actuated by rotating the actuating lever (38). the housing (32) contains an opening (44) that makes it possible to gain external access to a region of the actuating lever (38) that lies outside of the rotational axis (36) so as to subject the actuating lever (38) to the influence of a pedal movement, and in that the actuating lever (38) acts upon at least one measurement device (114, 118) for generating an electrical signal that corresponds to the rotational position of the actuating lever (38).

Documents:

281-cal-2001-granted-abstract.pdf

281-cal-2001-granted-claims.pdf

281-cal-2001-granted-correspondence.pdf

281-cal-2001-granted-description (complete).pdf

281-cal-2001-granted-drawings.pdf

281-cal-2001-granted-examination report.pdf

281-cal-2001-granted-form 1.pdf

281-cal-2001-granted-form 18.pdf

281-cal-2001-granted-form 2.pdf

281-cal-2001-granted-form 26.pdf

281-cal-2001-granted-form 3.pdf

281-cal-2001-granted-form 5.pdf

281-cal-2001-granted-letter patent.pdf

281-cal-2001-granted-priority document.pdf

281-cal-2001-granted-reply to examination report.pdf

281-cal-2001-granted-specification.pdf

281-cal-2001-granted-translated copy of priority document.pdf