A DEVICE AT AN OPERATING HANDLE FOR PARKING BRAKES

Abstract: Apparatus for a lever (6) for controlling a parking brake including brake units and an electrically driven tightening means for applying or releasing a braking force on the said brake units. Characteristic of the invention is that a means is arranged to detect the position of the lever and produce control signals to a first electric motor (12) for generating a brake force corresponding to the position of the lever. The lever can be adjusted manually. Further there is a second electric motor (49) intended to automatically control the lever (6) depending on incoming control signals. In the fully applied position the lever (6) is locked against manual adjustment.

Description: A DEVICE AT AN OPERATING HANDLE FOR PARKING BRAKES The present invention relates to an apparatus for a lever for controlling a parking brake intended for vehicles including brake units such as drum brakes or disc brakes on two opposing wheels in a pair of wheels and an electrically driven tightening means for applying or releasing a braking force on the said brake units. A large number of suggestions for electrically manoeuvred parking brakes for replacing conventional hand controlled parking brakes are known. Electrically manoeuvred hand brakes are described for instance in GB 2 304 838 A, WO 92 21 542 and EPO 398 546 A2. The purpose of the present invention is to achieve an electrically manoeuvred parking brake with a number of advantages compared to previously known designs. This is achieved according to the invention mainly through at least one means being arranged to sense the position of the manoeuvre lever and provide control signals to a first electrical motor intended to drive the said tightening means for generating braking power corresponding to the position of the lever, the lever being manually adjustable, a second electrical motor being arranged to manoeuvre the lever depending on control signals being input to it, and that when the lever is completely tightened in a locked position the same second electrical motor being arranged to lock the lever and prevent hand adjustment. The present invention offers the following advantages, among others: Clear indication to the driver of when the brake has been set or released automatically because the lever moves to the right position by itself. Simple function and use. Good child protection. An extra child protection lock is automatically applied when certain situations occur, for example when the driver leaves his seat, without making normal use difficult. The braking powers are adjustable to desired levels using appropriate springs. - The apparatus can be fit to all types of electrical parking brakes by proper positioning. Installation is simple as the whole apparatus can be made in a module. - Placement is the car can be changed without affecting the function of the apparatus. In the following the invention will be described in more detail with reference to embodiments shown in the attached drawings where Fig.1 shows schematically a section through a car to illustrate appropriate positioning of the main parts of the parking brake according to the invention. Fig.2 shows the important parts of an appropriate unit for activating the two brake units of a pair of wheels with the said activation unit in a position such that the parking brake is released. Fig. 3 shows the unit according to Fig. 2 in a position such that the parking brake is set. Fig. 4 shows some further details of the unit according to Fig. 2 and 3. Fig. 5 and 6 show the unit according to Fig. 2-4 viewed from the side to show a mechanism for manual mechanical release of the parking brake. Fig. 7 shows a blow up sketch of an energy storage spring included in the unit according to Fig. 2-6. Fig. 8-10 show the important parts of the function of the manoeuvre lever. Fig. 11 shows an appropriate lever guide arm and its co-operation with the lever. Fig. 12 and 13 show schematically the angular travel of the lever and the angular travel of the lever arm of the braking unit, respectively. Fig. 14 shows an example of an appropriate guide scheme for the parking brake. In Fig. 1 a plastic box is designated 1. In it there is a brake activation unit. From that unit brake wires 2, 3 extend to brake units in the two wheels 4, 5. A lever 6 for manoeuvring the parking brake is arranged in the middle console of the car. The lever 6 and the activation unit in the plastic box 1 are coupled to an electric control unit 7. A mechanical release wire is designated 8. It is used to release the brake in case of current failure or other electrical fault. A glider 9 is shown in Fig. 2. It is adjustably placed in glide rails 10, 11 and is attached at either end to a first and a second brake wire 2, 3. On the glider there is an electric motor 12 (Fig. 4) which via its gearbox drives a lever arm 14 attached to swing on the glider. Its axle is designated 15 in the drawings. On the free end of the lever arm there is a lever arm peg 16 that sticks up and to which the first brake wire 2 is attached. The other brake wire 3 is coupled to the glider via a wire stretcher 38 and a spring package in which there is an energy storage spring 18. The wire stretcher 38 can be equipped with a strain gauge (not shown). In the spring package there is an outside cylinder 19 containing the said spring. It is adjustably attached to a cylinder guide 20 and attached by one end to a shank 21 on a bent rod, in the following designated return 22, the middle part 23 of which is adjustably attached to the glider 9 in a return holder 24. The return 22 has a second shank 25 on the other side of the lever arm peg 16 relative to the outer cylinder 19 of the spring package. In the position shown in Fig. 2 the return's second shank lies against the lever arm peg 16 which sticks up above the other shank. In Fig. 3 the lever arm 14 has swung from its unloaded original position shown in Fig. 2 in which the lever arm rests against a stop lug 26. In the position of the lever arm shown in Fig. 3 the spring package with the spring 18 is held in position on the glider only by the lock 27 which in its normal position, the locked position, retains the outer cylinder 19 and takes up the stress in the other wire. The lock is lifted against a pressure spring 28 out of its locking position on pulling the release wire 8. This manual mechanical release mechanism is described in more detail below in connection to Fig. 5 and 6. On the glider there is a number of microswitches. A first one 29 that indicates the original position of the lever arm peg 16, a second one 30 that indicates the final position of the lever arm peg and a third one 31 that indicates when the brake is mechanically released through the release wire 8. The parking brake is released when the activation unit is in the position shown in Fig. 2. The electrical motor 12 is arranged to swing the lever arm 14 on activating the brake whereby the lever arm peg 16 makes a clockwise rotational movement from its original position to its final position simultaneously pulling the first wire 2 to stretch it. The glider 9 which is arranged to glide in the glide rails 10, 11 is moved with the first wire 2 and the reaction force is taken up by the second wire 3 whereby the same force is always applied to the two wires. The gearbox of the electric motor 12 is self- regulating which means that the lever arm 14 can be stopped and held in any position. This makes dynamic braking with the parking brake possible. When the vehicle is to be parked the lever arm is drawn to its final position as shown in Fig. 3 and 4. In that position the lever arm peg 16 and therefore the force vector of the wire 2 has passed the rotation centre 15 of the lever arm whereby the lever arm is pressed against the stop lug 26 and held in that self locking position. The system is adjusted so that a somewhat greater than necessary force is applied to the wires. The energy storage spring which is pre-compressed to the necessary applied force is thereby further compressed to compensate for force changes that can occur for example in connection with cooling off the brake discs. When the parking brake is drawn the lever arm can be returned to its original position by the electric motor to release the brake. As mentioned above in the activation unit there is a manual mechanical release mechanism with which the parking brake can be released if the electric motor does not work, for instance because of a discharged battery. The function of the manual mechanical release mechanism is best clarified by Fig. 5 and 6. In Fig. 5 the lock 27 has been lifted up out of engagement with lock pegs on the outside cylinder by pulling the release wire 8 whereby the outside cylinder 19 is released and the spring package can now be brought out of its previously fixed position shown in Fig. 5 by the force of the wire. When the outside cylinder slides in the cylinder guide 20 also the glider 9 is moved until the wires 2, 3 slacken and the parking brake is deactivated. The return 22 described above which moves with the outside cylinder when it is freed comprises a connection between the energy storage spring and the lever arm of the electric motor. When the electric motor is again functional and the lever arm returns to its original position the return is pressed back by the lever arm plug 14 and the outside cylinder 19 is brought back to its original position as shown in Fig. 5. In that position the pressure spring 28 forces the lock 28 to engage against the outside cylinder. The parking brake is thus automatically made functional when the manual mechanical release mechanism is used and the electric motor is again functional. A significant advantage of this is that the vehicle does not need to be driven to a garage each time the release mechanism has been used. The spring package according to Fig. 7, which as mentioned above is placed on the glider 9 and in terms of force connected to the other wire 3 consists of the outside cylinder 19, a rod 33 placed in it, the spring 18, a stop 34, the lock pegs 32 which are fastened to the stop and in applied position extend out of the holes 35 in the outside cylinder for co-operation with the lock 27, a pre- stressing nut 36, a lock nut 37 and a wire stretcher 38 one end of which can be screwed tightly to the rod 33 and the other end of which is intended to be connected to the other wire 3. If the force in the wire 3 exceeds the force in the spring the rod can slide in the central hole in the stop. The purpose of the spring is to store energy for thermal changes and to be a position and energy reserve for relaxation in the system. The requirement placed on the spring is that it shall store energy from the forces that exceed the minimal locking force. Additionally it shall be possible to deform it by an amount of the order of magnitude of 5 mm. As mentioned above, the activation unit of the brake is contained in a plastic box 1 , Fig. 1 , and attached to a chassis plate (not shown) equipped with a wire guide, not shown, to steer the wires correctly in relation to the glider 9. The whole activation unit with its chassis plate and surrounding plastic box 1 is easy to place in the vehicle. It is appropriately placed between the back wheels as shown in Fig. 1 for the shortest wires. The design is very good for adjusting position using the lever 6 as shown in Fig. 1 because the lever arm has limited rotational freedom, of the order of 0- 195 degrees. Position adjustment is an advantage for dynamic braking. Manually the parking brake is activated by the lever 6 placed in the middle console. The manoeuvre lever 6 can be controlled both manually and automatically, as described in the following with reference to Fig. 8-10. On its lover end the lever 6 is fastened in a lever base 39 which is rotationally attached to a bracket 40. As mentioned above the lever unit is placed in the middle console of the vehicle. The lever base can be rotated in the direction of the vehicle and spring loaded in the forward direction with a torsion spring 41. The manoeuvre lever can be rotated around an axle 42 in the lever base and as most clearly seen in Fig. 10 it can be rotated sideways a little. Inside the lever base 39 there is a compression spring positioned against the bolt 43, which spring is arranged to press the lever toward the right around the axle 42. The path of the lever's 6 motion is determined by a guide slit 45 in a guide plate 44. It has a control part in the direction of the vehicle. It guides the motion of the lever from the released state at A to the fully applied state at B and vice versa. As mentioned above the lever base is spring loaded forward by the torsion spring 41. Because pulling the brake wires takes place electrically the resistance in the lever to the pulling motion in the control part 45 can be set arbitrarily through choice of the torsion spring 41. When the lever is in position B, that is, completely pulled up, it can be moved to the right along the transverse part 46 of the guide slit. The lever is also pressed toward the right in position B by the pressure spring in the base of the lever. In the guide slit there is also a locking part 47 in which the lever is held in its applied state. If it is not locked against manual operation, which lock is described below, the lever can be moved out of its locked position in the locking part 47 to position B against the action of the torsion spring 41 and the pressure spring in the lever base. The lever does not remain in position B but is brought to position A by the torsion spring if the driver does not stop it. Dynamic braking can be applied by moving the lever from position A toward position B. The position of the lever in the control part between positions A and B is sensed by a potentiometer (not shown) which produces a control signal proportional to the displacement of the lever. In the apparatus according to the invention the lever is moved automatically from the totally released position to the fully applied position and vice versa depending on control signals that indicate the situation at hand, for example that the driver leaves the driver's seat. The automatic motion of the lever takes place through a lever guide 48 that is powered by another electric motor 49. As is most clearly seen in Fig. 9 it is screwed to the outside of the console 40 and has a belt wheel 50 on its output axle. A gear belt 51 transfers the force from the electric motor via a belt wheel 52 to the lever guide 48 which is a lever arm. It can rotate around an axle 53 fastened to the guide plate 43 and the bracket 40. In Fig. 10 the guide place has been removed to illustrate the function of the lever guide. When the lever is in its released position, that is, position A, the lever can be moved to the wholly applied position by the lever guide when it is rotated counter clockwise around its axle. When the lever has reached position B the pressure spring in the base of the lever presses it to the right and further into the locked position in the locking part 47 of the guide slit 44 by the torsion spring 41. In that position the lever can be locked by the lever guide so that manual adjustment of the lever from that position is not possible. The lever 6 can be returned from the locked position to a completely released position by rotating the lever guide 48 clockwise. In Fig. 10 the lever guide has been shown in a simplified form. For the lever guide 48 to function in the way intended its geometric form has to be adjusted to the desired lever motion and the locking function. A preferred embodiment of the lever guide is shown in detail in Fig. 11. In Fig. 11 in addition to the lever guide 48 the guide slit 44 and the lever (only in cross section) are also shown. The lever guide 48, which rotates around the axle 53, is shown in Fig. 11 in two different positions. A locking position (full line) and another position (dashed line) where the lever guide holds a released lever, in position A. The lever is moved from position A when the lever guide is rotated counter clockwise during which the lever is moved by a guiding part 54 of the lever guide between positions A and B in the guide slit 44. In the dashed position of the lever in Fig. 11 the said guiding part is shown holding the lever in position A. From position B the lever is brought to the right to position C by the pressure spring in the lever base and thence by the torsion spring to the locked position D. When control signals to the electric motor 49 indicate locking the lever in its locked position the lever guide is rotated counter clockwise until the locking part 55 of the lever guide, in the form of a notch, surrounds the lever 6 as shown by the full lines in Fig. 11. To release the lever from its wholly locked position D the lever guide 48 is rotated clockwise from the lever guide position in Fig. 11 shown in full lines. Then the lever is disengaged from the locking part 55 which is a notch in the lever guide in the shown embodiment. When it is rotated clockwise to the lever position shown with dashed lines in Fig. 11 the release part 63 of the lever guide is engaged with the lever at the position marked d on the lever guide. On further clockwise rotation the distance is increased between the rotation axle of the lever guide and the edge of the lever guide which is engaged with the lever. Against the action of the torsion spring 41 the release part 63 brings it out of position D in the guide slit to position C where the lever guide rotates clockwise and the edge part engaged with the lever moves from d to the position marked c. On further clockwise rotation the lever is moved from position C in the guide slit to position B against the action of a pressure spring when the release part 63 engaged with the lever is moved from position c to the position marked b. When the lever reaches position B it is brought to position A by the torsion spring 41. In summary the release part 63 between the edge parts d to b moves the lever from position D to B while the guide part 54, limited by the edge parts a and b, brings the lever from position A to position B. Fig. 12 and 13 show the displacement of the lever between the completely released position A and the fully drawn lever, position B, respectively, corresponding to rotating the lever arm 14 in the wire tightening unit. In the embodiment shown the lever is moved 44° between position A and position B and the corresponding displacement of the lever arm 14 from slack wire 2 in position A1 to a position B1 where the braking torque is maximal is for example of the order of 135°. The braking torque is controlled by a potentiometer that senses the angular position of the lever. This angular position is compared with a potentiometer on the electric motor 12 of the lever arm 14. The braking torque can thus be controlled so that it is proportional to the displacement of the lever. In the above mentioned numerical example, for dynamic braking the system shall rotate the lever arm of the braking unit at least 135 degrees from the original position when the lever is in position B. However, the lever arm of the braking unit shall not reach its maximal braking torque before the lever is in position B, but at position B1 the lever arm of the braking unit in the said numerical example shall have rotated at least 135 degrees from its original position. When the lever is brought to the locked position, that is, moved between C and D in Fig. 12, the lever arm 14 of the braking unit is moved from position B1 to the stop lug 26. As has been described above in connection with Fig. 3 and 4 the lever arm takes up a self locking position when it rests against the stop lug. The braking system is designed to have a number of automatic functions. It shall be possible to release and apply the parking brake automatically when certain chosen conditions for the respective functions are fulfilled. In Fig. 14 an example of an electrical diagram with details included in the automatic system of the brake is shown, the system being controlled by a control unit 7. The latter is coupled to an electric motor 12 via an ammeter 56 and a potentiometer 57 that is used for comparison with the position of the lever arm 14. The microswitch 58 that indicates the applied brake and the microswitch 59 that indicates the released brake are connected to the control unit. Further, signals from a sensor 60 in an ignition lock that shows key in or key out and signals from a presence detector 61 in the diver's seat that indicates whether the driver is seated there or not are lead to the control unit 7. A torque sensor 62 provides information about when the engine is powering the vehicle. The electric motor 49 that drives the lever guide and an ammeter 65 for the current through the electric motor 49 are coupled to the control unit. Further the potentiometer 66 that senses the angular position of the manoeuvre lever is coupled to the control unit 7. In addition to that which is mentioned above the system appropriately includes two end position sensors 63, 64 for the lever, sensors 67 in the door locks that sense whether the doors are locked or not and sensors 68 in the gear lever and brake pedal. An automatic function in the parking brake is that the brake shall release automatically when the vehicle starts to move. This happens when the following conditions are met: - The ignition is on The driver is seated The motor is powering the vehicle. This has been realised by letting the said sensors in the ignition lock and the driver's seat produce signals to the control unit while the latter retrieves information from the motor electronics. There are times when the brake must not release automatically. Examples are the following cases: No driver in the driver's seat The motor is running The vehicle has been hit There is no voltage or the voltage has just been applied - Electrical failure, short circuit This is realised using the sensor in the chair while the motor does not signal powering the vehicle. The brake shall be applied automatically in the following cases: When the car rolls backward and a forward gear (first gear) has been chosen The car rolls forward when reverse gear has been chosen When the ignition key has been taken out. Also here the sensor in the ignition lock is used. The control unit must also have information from the sensor in the gearbox for identification of the gear chosen while the ABS system of the car provides the information that the car is in motion. Further, it is important that the brake not apply itself in the following situations: When being towed When a wheel is locked while the car is moving - When there is an electrical failure It is therefore important to be able to turn the automatic control off. It is always possible to apply the brake but releasing the brake from its locked maximum position is possible only when the second electric motor is activated and withdraws the lever guide from its locked position. When the ignition is on and someone is sitting in the driver's seat the lever guide has been moved from the locked position and the lever can be manoeuvred freely. When no one is seated in the driver's seat the lever cannot be moved from its locked position. This increases children's safety. The system is appropriately so designed that when the ignition is off and someone is sitting in the driver's seat the brake pedal must be depressed in order that the lever guide be released from its locked position. This also increases children's safely. The invention is not restricted to the above described embodiments. Rather, many modifications are possible within the scope of the appended claims. The automatic control of the lever can be changed, of course. The electric braking unit can be of a different type to that which has been described above in connection with Figs. 2-7. For example the braking units need not be activated by wires but can be electromechanical brakes applied directly to the respective wheel.

Claims: CLAIMS 1. Apparatus arranged in connection with for a lever for controlling a parking brake intended for vehicles, said parking brake including brake units such as drum brakes or disc brakes on two opposing wheels (4,5) in a pair of wheels and an electrically driven tightening means for applying or releasing a braking force on the said brake units characterised in that at least one means is arranged to sense the lever's (6) position and produce control signals to a first electric motor (12) intended to power the said tightening means for generation of braking power according to the position of the lever (6), the lever (6) being manually adjustable, a second electric motor (49) is arranged to manoeuvre the lever according to control signals input to it and the same electrical motor being arranged to lock the lever and prevent hand adjustment when the lever (6) is in the completely applied locking position. 2. Apparatus according to claim 1 , characterised in that a lever guide arm (48) driven by the second electric motor (49) is arranged to manoeuvre the lever (6) whereby the lever guide arm (48) brings the lever (6) to its different adjustment positions including a released position (A) and a completely applied locked position (D) where the lever guide arm (48) is arranged to lock the lever and prevent hand adjustment when the lever is in its completely applied locked position. 3. Apparatus according to claim 2, characterised in that the lever guide (48) consists of a lever arm driven by the second electric motor (49) and has a guide part (54) arranged to bring the lever from its released position (A) to its completely applied position (B). 4. Apparatus according to claim 3 characterised in that the lever guide (48) has a locking part (55) arranged to mechanically lock the lever when it is moved to its completely applied locking position. 5. Apparatus according to claim 3 or claim 4, characterised in that the lever guide has a release part (63) arranged to bring the lever out of its locked position to its released position whereby the lever guide is rotated in the opposite direction to the application direction. 6. Apparatus according to one of the previous claims, characterised in that the lever (6) is attached by its lower end to a lever base (39) that can rotate in the direction of the vehicle, the lever together with the lever base can be rotated backward from a forward position in which the brake is released toward a back position in which the brake is fully applied, the lever base (39) being spring loaded forward, appropriately by a torsion spring (41) whereby pulling the brake by the lever is opposed by the said torsion spring, the lever (6) attached to the lever base (39) can be rotated relative to the lever base transverse to the direction of the vehicle, the path of motion of the lever (6) being guided by a guide slit (44) in the guide plate (43) that has a control part (45) extending in the direction of the vehicle which is arranged to guide the lever (6) in its motion backward from its released position to its fully applied position and vice versa, the back part of the guide slit (44) extending to the right in a transverse part (46) and the slit thereafter changing to a short forward facing locking part (47) and a pressure spring is arranged in the lever base (39) intended to press the lever (6) to the right whereby in the fully applied position (8) the lever is pressed to the right by the pressure spring and then into its locking position in the locking part (47) of the slit by the said torsion spring (41). 7. Apparatus according to one of the previous claims, characterised in that the parking brake includes a glider (9) that can be moved in two opposing directions, a first brake wire (2) attached to one wheel's brake unit being connected to the glider (9) and arranged to extend from it in the said direction of motion, a second brake wire (3) attached to the other wheel being connected to the glider (9) and arranged to extend from it in the said direction of motion but in the opposite direction to the first brake wire (2), the first electric motor (12) and the tightening means being attached to the glider, the tightening means being connected to the first brake wire (2) and the glider (9) being arranged to be moved in the tightening direction so that the applied force in the first brake wire (2) produces a reaction force in the other brake wire (3) whereby the same brake force is distributed to the respective brake units of the wheel pair. 8. Apparatus according to claim 9, characterised in that the said tightening means consists of a lever arm (14), the first wire (2) is fastened on a lever arm peg (6) that is placed on the lever arm (14) at a distance from its centre of rotation (15) and on tightening the first wire (2) the lever arm (14) is arranged to make a rotational motion during which the lever arm peg (16) is brought around the said rotation centre (15) from a starting position to a final position at a stop lug (26), the stop lug being arranged so that in the said final position the force vector of the first wire (2) locks the lever arm mechanically against the stop lug. 9. Apparatus according to claim 7 or 8, characterised in that the said wires (2,3) are coupled to an energy storage spring (18) on the glider (9) arranged to compensate for thermal changes and possible relaxation in the wire system. 10. Parking brake according to claim 9, characterised in that the second wire (3) is coupled to the spring (18) and the arrangement includes a manual mechanical release mechanism arranged to allow mechanical release of the parking brake when one of the electric motors is not in operation. 11. Parking brake according to claim 10, characterised in that the release mechanism includes a locking means that in its normal position holds the spring (18) in place on the glider (9) and a release wire (8) arranged to move the release mechanism out of its engaged position through manually pulling the wire against the action of a pressure spring (28) whereby the brake unit is released on moving the spring (18) relative to the glider (9), a return (22) is attached to the spring (18) and arranged to move with it on moving the spring in connection with its release, the return having a part that when the brake is released mechanically is on the opposite side of the lever arm peg (16) relative to the spring as seen in the direction of the motion of the glider, the return (22) being shaped so that the said part is moved by the lever arm peg (16) when after mechanical release of the brake the electric motor is again activated and is returned to its initial position whereby the spring (18) is brought to its normal position and the lock (27) is brought to hold the spring in place through the action of the pressure spring. 12. Apparatus according to one of the previous claims characterised in that the lever (6) for guiding the parking brake is placed near the driver's seat and the tightening means and the first electric motor (12) are arranged between the said wheels (4,5) or near them. 13. Apparatus according to one of the previous claims characterised in that the control unit (7) is arranged to control the first (12) and the second (49) electric motors depending on the input signals from a number of sensors including the said sensors for the position of the lever, a sensor (60) in the ignition lock that indicates whether the ignition key is inserted or not, a presence detector (61) in the driver's seat indicating whether the driver is seated in the seat or not and sensors for indicating whether the parking brake has been set or released.

Inventors: LUNDHOLM FREDRIK, MARKLUND JESPER, LUNDHOLM, FREDRIK, MARKLUND, JESPER
Applicants: LUNDHOLM FREDRIK, MARKLUND JESPER, VOLVO PERSONVAGNAR AB, LUNDHOLM, FREDRIK, MARKLUND, JESPER
Application year: 1999
Main classification: B60T13
IPC codes: B60T7