WO2009007505A1 - Electromechanic parking brake arrangement - Google Patents

Electromechanic parking brake arrangement Download PDF

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Publication number
WO2009007505A1
WO2009007505A1 PCT/FI2008/050414 FI2008050414W WO2009007505A1 WO 2009007505 A1 WO2009007505 A1 WO 2009007505A1 FI 2008050414 W FI2008050414 W FI 2008050414W WO 2009007505 A1 WO2009007505 A1 WO 2009007505A1
Authority
WO
WIPO (PCT)
Prior art keywords
brake
drum
power unit
power supply
motion bar
Prior art date
Application number
PCT/FI2008/050414
Other languages
French (fr)
Inventor
Mauno Keski-Luopa
Original Assignee
Actioneco Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Actioneco Oy filed Critical Actioneco Oy
Publication of WO2009007505A1 publication Critical patent/WO2009007505A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/74—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive
    • B60T13/746—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive and mechanical transmission of the braking action
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D51/00—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like
    • F16D51/46—Self-tightening brakes with pivoted brake shoes, i.e. the braked member increases the braking action
    • F16D51/48—Self-tightening brakes with pivoted brake shoes, i.e. the braked member increases the braking action with two linked or directly-interacting brake shoes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D51/00—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like
    • F16D51/16—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis
    • F16D51/18—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes
    • F16D51/20—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes extending in opposite directions from their pivots
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D51/00—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like
    • F16D51/16—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis
    • F16D51/18—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes
    • F16D51/20—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes extending in opposite directions from their pivots
    • F16D51/22—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes extending in opposite directions from their pivots mechanically actuated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D65/00—Parts or details
    • F16D65/14—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position
    • F16D65/16—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake
    • F16D65/22—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake adapted for pressing members apart, e.g. for drum brakes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2121/00—Type of actuator operation force
    • F16D2121/14—Mechanical
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2121/00—Type of actuator operation force
    • F16D2121/18—Electric or magnetic
    • F16D2121/24—Electric or magnetic using motors

Definitions

  • the invention relates to an electromechanic parking brake arrangement according to the preamble of claim 1.
  • an electromechanic parking brake utilizing a drum brake fitted in a wheel.
  • An electromechanic actuator which is an electric motor, operates the drum brake in order to achieve a braking effect.
  • the expander elements of the brake shoes are provided with a screwing tap, and the electric motor is respectively provided with a spiraling gear wheel, these two being arranged to be mutually effective.
  • the expander elements of the brake shoes function so that the brake shoes are made to be turned outwards and pressed against the brake drum.
  • the parking brake is in operation, and the wheel cannot rotate.
  • the expander elements of the brake shoes function so that the brake shoes are turned inwards and released from the brake drum.
  • the parking brake is not in operation anymore, in which case the wheel is again free to rotate.
  • a drawback with the above described electromechanic parking brake is that in order to function appropriately, it always requires a power supply. Another drawback is that owing to its structure, the parking brake functions relatively slowly.
  • the object of the invention is to eliminate the drawbacks connected to the above described electromechanic parking brake arrangement.
  • Another object of the invention is to realize a new electromechanic parking brake arrangement that is particularly suited in light, electrically driven vehicles.
  • An electromechanic parking brake arrangement according to the invention for a vehicle, particularly an electrically driven vehicle, said vehicle being provided with a DC power supply, such as a battery, comprises an electromagnetic actuator and a drum brake that is arranged in connection with one or several wheels of the vehicle; said arrangement further comprises a brake drum, two brake shoes and their expander elements; said brake shoes are fitted symmetrically in the brake drum, and said actuator is used for manipulating the expander elements and the brake shoes.
  • the electromagnetic actuator in the electromechanic parking brake arrangement is a linear power unit, the motion bar of which has two positions, a first position and a second position, and the motion bar can be shifted between said positions by sending an electric control signal to the power unit; further, the motion bar is connected to the drum brake expander elements, so that when the motion bar is in the first position, the two brake shoes of the drum brake are in the rest position, so that the drum brake is not in operation, and in the second posi- tion, the two brake shoes of the drum brake are in the working position, pressed against the brake drum, in which case drum brake is in operation;
  • the electromechanic brake arrangement comprises a control unit of the power unit, having a first circuit, including a first relay and a first electric reserve power supply that is connected, through a relay switch, to the power unit, when the voltage of the DC power supply over the relay control winding is drastically dropped, and as a consequence, the power unit receives a control signal, in which case the motion bar of the power unit is shifted from
  • the linear power unit is a spindle motor.
  • the first reserve power supply is a first condensator that is charged from a DC power supply during the normal operation of the vehicle, and the electric charge stored in said condensator is discharged through the relay switch and the power unit, when the voltage of the DC power supply over the relay control winding is drastically dropped.
  • control unit of the power unit also has a second circuit, including a second electric reserve power supply and a switch, which are coupled in series in between the first pole of the DC power supply and the first pole of the power unit, where the second pole of the power unit is connected to the first pole of the DC power supply, and the switch is supposed to connect the first pole of the power unit to the reserve power supply, in which case the power unit receives a second control signal, and the motion bar is shifted from the second position to the first position, and by means of the motion bar, by the expander elements, the brake shoes of the drum brake are shifted to the rest position, and the wheel is thus released to rotate.
  • a second circuit including a second electric reserve power supply and a switch, which are coupled in series in between the first pole of the DC power supply and the first pole of the power unit, where the second pole of the power unit is connected to the first pole of the DC power supply, and the switch is supposed to connect the first pole of the power unit to the reserve power supply, in which case the power unit receives a second control signal
  • the second reserve power supply is a second condensator that is charged from a DC power supply during the normal operation of the vehicle; now the second pole of the power unit is connected to the first pole of the DC power supply, and the switch is supposed to connect the first pole of the power unit to the condensator, so that the charge stored in the condensator is discharged through the power unit, in which case the power unit receives a second control signal, and the motion bar is shifted from the second position to the first position, and by means of the motion bar, by the expander elements, the brake shoes of the drum brake are shifted to the rest position, and the wheel is thus released to rotate.
  • the second circuit of the control unit of the power unit also includes a second relay, the control winding of which is coupled in series with the switch, and these are together coupled in series with a second reserve power supply in between the first pole of the DC power supply and the first pole of the power unit, and the reserve power supply is connected, through a relay switch, to the power unit, when the switch is switched off; as a consequence, the motion bar is shifted from the second position to the first position, and by means of the motion bar, by the expander elements, the brake shoes of the drum brake are shifted to the rest position, and the parking brake is released.
  • a second relay the control winding of which is coupled in series with the switch, and these are together coupled in series with a second reserve power supply in between the first pole of the DC power supply and the first pole of the power unit, and the reserve power supply is connected, through a relay switch, to the power unit, when the switch is switched off; as a consequence, the motion bar is shifted from the second position to the first position, and by means of the motion bar,
  • An advantage of the invention is that it is mechanically simple, economical to manufacture and easy to maintain.
  • a particular advantage of the invention is that it functions, even if the voltage in the DC power supply of the vehicle, such as battery, were clearly dropped with respect to its normal value, and electric power could not be obtained therefrom.
  • the power unit is made to function without an immediate cooperation of a power supply. Thus it is not necessary for the power supply to function or to be able to generate sufficiently electric power for driving the power unit.
  • the parking brake arrangement also functions as an emergency brake, when the electric motors serving as the vehicle driving motors loose the supply voltage obtained from the DC power supply.
  • the electric driving motors particularly servomotors
  • their electromagnetic brake power is vanished.
  • the power unit receives a driving pulse from the first condensator of the first circuit of the control unit.
  • the motion bar of the power unit is shifted from the first position to the second position, and by means of the motion bar, by the expander elements, the brake shoes are shifted to the working position, in which case the parking brake begins to function, in this case in the way of an emergency brake.
  • Yet another advantage of a preferred embodiment of the invention is that the park- ing brake can be released by a simple and easy operation, when the vehicle should be transported, for example by pulling or pushing, away from the parking area.
  • An advantage here is that even in this case, the power unit is made to function without an immediate cooperation of the power supply.
  • the double function linear power unit is realized by a double function solenoid.
  • the double function linear power unit is realized by a spindle motor.
  • Figures 2A and 2B illustrate, in a top-view partial cross-section, the operation of a parking brake arrangement according to the invention, where the parking brake of Figure 2 A is not in operation, and where the parking brake of Figure 2B is in operation;
  • Figure 3 illustrates another parking brake arrangement according to the invention, where the drum brake is viewed from the top, in partial cross-section;
  • Figure 4 illustrates a brake element, i.e. that part of the drum brake that is fitted inside the brake drum, seen at an inclined angle from above;
  • FIG. 5 is a side-view illustration of the brake element shown in Figure 4.
  • the electromechanic parking brake arrangement according to the invention is meant for a vehicle, particularly an electrically driven vehicle.
  • This kind of vehicle is provided with a DC power supply 7, such as a battery, from which its electric motors and other electric systems receive their electric power.
  • the electrically driven vehicle is for example an electrically driven, independently mov- able device that is described in the international patent application PCT/FI2007/000096 by the same applicant.
  • the parking brake arrangement 1 comprises an electromagnetic actuator 2 and a drum brake 3, which is fitted in connection with the vehicle wheel and with the drive motor unit most advantageously arranged therein. Both the actuator 2 and the drum brake 3 are fastened to the wheel support arrangement.
  • the actuator 2 is preferably arranged in connection with the vehicle frame, in the vicinity of the wheel support arrangement.
  • the drum brake 3 comprises a brake drum 30, two brake shoes 31, 32 and expander elements of the brake shoes 330.
  • the brake shoes 31, 32 are arranged symmetrically inside the brake drum 30.
  • the expander elements of the brake shoes 330 are operated by the electromechanic actuator 2.
  • the brake mechanism comprises at least brake shoes 31, 32 and their expander elements 330.
  • the drum brake 3 is fitted in the hub of the wheel, so that the brake shoes 31, 32, particularly their friction surfaces, can be used for manipulating the brake drum 30 arranged in connection with the wheel and rotating therealong, and particularly the inner surface thereof, when the rotary motion of the wheel should be interrupted, and in this case when the wheel should particularly be locked in a non-rotary position.
  • the structure of the drum brake 3 in itself is known from the prior art.
  • the purpose of the electromagnetic actuator 2 is to operate the expander elements 330 of the drum brake 3, and thereby the brake shoes 31, 32, particularly for achieving a braking function.
  • the electromagnetic actuator 2 is provided with a linear power unit 20, including a motion bar 21.
  • the power unit 20 is a double function solenoid 201.
  • the driving pulse or the like is preferably generated by means of a relatively fast and sufficiently high voltage change between the solenoid poles 2Oa 5 2Ob 5 as a consequence of which a power pulse or a corresponding sufficiently long power signal is induced in one or several windings of the power unit 20, which signal makes the motion bar 21 move between the positions A 5 B.
  • the motion bar 21 of the solenoid 201 is connected, either directly (cf. Figures 2 A and 2B) or indirectly (cf. Figure 3), to the drum brake 3, particularly to the expander elements 330 of the brake shoes 31, 32.
  • the motion bar 21 of the solenoid is in the first position A, the two brake shoes 31, 32 of the drum brake 3 are in the rest position, and their friction surfaces are not in contact with the brake drum 30. Now the drum brake 3 is not in operation, and any braking operation directed to the rotary motion of the wheel is not effective.
  • the electromechanic brake arrangement comprises a control unit 4 of the power unit, provided with a first circuit 40.
  • Said circuit 40 includes a first relay 41 and a first electric reserve power supply 42.
  • the first reserve power supply 42 is realized by means of a first con- densator 421, as shall be described in the specification below.
  • the reserve power supply 42 is realized by means of a rechargeable battery that is small in size, but sufficient for the use of the power unit 20 as regards the charging capacity.
  • the first condensator 421 there is arranged an electric charge from a DC power supply 7.
  • the charging of the condensator 421 is generally realized during the normal operation of the vehicle. This refers to the normal use of the vehicle, where the vehicle is transported and/or used for carrying out the designated tasks.
  • the electric charge stored in the condensator 421 is discharged (at least partly) through the relay switch 41c and the solenoid 20, when the voltage of the DC power supply 7 over the control winding 41a of the relay is cut or is in general drastically dropped.
  • the solenoid 20 receives a driving pulse, and as a result, the solenoid 20 functions so that the motion bar 21 is shifted from the first position A to the second position B.
  • the movements of the motion bar are transmitted to the expander elements 330 of the drum brake 3, by means of which the brake shoes 31, 32 are shifted to the working position, and the parking brake begins to work.
  • the control winding 41a of the first relay 41 is coupled in between the poles 71, 72 of the DC power supply 7.
  • the first condensator 421 is coupled in between the poles 71, 72 of the DC power supply 7 through the first switch 41b of the relay 41.
  • the first pole 20b of the solenoid 20 and the condensator 421 (its second pole) are mutually coupled through the second switch 41c of the relay 41.
  • the second pole 20a of the solenoid 20 and the condensator 42 (its first pole) are connected to the first pole 71 of the DC power supply 7.
  • the first switch 41b is closed, i.e.
  • the second switch 41c of the relay 41 is open, i.e. it is not electroconductive. Moreover, it is assumed that the motion bar 21 of the solenoid 20 is in the first position A.
  • the voltage change first affects the control winding 41a of the relay 41 through the switches 41b, 41c of the relay 41, which change their switching position. Now the first switch 41b is opened and the second switch 41c is closed (illustrated by dotted lines Figure 1).
  • the first switch 41b cuts the current route between the condensator 421 and the second pole 72 of the DC power supply 7, and the second switch 41c of the relay 41 connects the first pole 20b of the solenoid 20 to the condensator 42. Because the second pole 20a of the solenoid 20 is connected to the first pole 71 of the DC power supply 7, the charge stored in the first condensator 421 is discharged (at least partly) through the solenoid 20, and the solenoid receives a first driving pulse. As a consequence, the solenoid 20 functions so that the motion bar 21 is shifted from the first position A to the second position B. The movement of the motion bar 21 is transmitted to the expander elements 330, so that the brake shoes 31, 32 of the drum brake 3 are shifted to the working position, and the parking brake begins to work.
  • the control unit 4 of the power unit in the electromechanic brake arrangement comprises a second circuit 50, including a second electric reserve power supply 51 and a switch 52.
  • the second re- serve power supply 51 is advantageously realized by means of a second condensator 511, as shall be described below, with reference to the next preferred embodiment.
  • the second reserve power supply 51 is realized by means of a rechargeable battery, for instance a first reserve power supply 42.
  • the second condensator 511 and the switch 52 are coupled in series in between the first pole 71 of the DC power supply 7 and the first pole 20b of the solenoid 20.
  • a suitable electric charge is arranged in the second condensator 511 from the DC power supply 7 (for example during the normal use of the vehicle).
  • the second pole 20a of the solenoid 20 is connected to the first pole 71 of the DC power supply 7.
  • the electric charge stored in the condensator 511 is discharged (at least partly) through the solenoid 20, in which case it receives a second driving pulse.
  • the solenoid 20 functions so that the motion bar 21 is shifted from the second position B to the first position A.
  • the movement of the mo- tion bar 21 is transmitted to the expander elements 330, so that the brake shoes 31, 32 of the drum brake 3 are shifted to the rest position, and the wheel is thus released to rotate and the parking brake is not in operation anymore.
  • control unit 4 of the second circuit 50 of the power unit also comprises a second relay 53.
  • the control winding 53a of this switch is coupled in series with the switch 52.
  • the control winding 53a and the switch 52 are together coupled in series with the second condensator 511 in between the first pole 71 of the DC power supply and the first pole 20b of the solenoid 20.
  • the second condensator 51 is coupled at the second pole through the second switch 53 c of the relay to the second pole 72 of the DC power supply 7, and at the first pole 71 to the DC power supply 7 in order to obtain the desired electric charge.
  • the electric charge stored in the second condensator 511 is discharged through the first switch 53b of the second relay 53 and through the solenoid 20, when the switch 52 is closed.
  • the current route of the condensator 511 to the DC power supply 7 (to its second pole 72) is interrupted by opening the second switch 53c of the second relay 53.
  • the second condensator 511 is first discharged through the control winding 41a, and further, when the relay is in operation, through the first switch 53b of the relay 53.
  • the solenoid 20 functions so that the motion bar 21 is shifted from the second position B to the first position A.
  • the movement of the motion bar 21 is transmitted to the expander elements 330, so that the brake shoes 31, 32 of the drum brake are shifted to the rest position, and the parking brake is released.
  • the first pole 71 of the DC power supply 7 is in positive voltage
  • the second pole is in zero, i.e. earth potential.
  • This can also be arranged in another way; the essential factor in this case is that a sufficient voltage prevails between the poles of the DC power supply.
  • the drum brake 3 that is applied in the electromechanic parking brake arrangement according to the invention comprises a brake mechanism including two curved drum elements 31a, 32a and brake shoes 31, 32 arranged in connection with both (cf. Figure 4 and 5).
  • the drum elements 31a, 32a are turnably interconnected at their first end by a hinge pin 34 or a corresponding element.
  • the expander elements 330 belonging to the brake mechanism are arranged in between the other ends of the drum elements 31a, 32a and simultaneously of the brake shoes 31, 32.
  • the drum elements 31a, 32a together form a circular ring, and on the circumference of said ring, there is located the hinge pin 34 and, at the distance of 180 de- grees therefrom, the center point of the expander elements 330.
  • the 330 drum elements 31a, 32a and the brake shoes 31, 32 can be pushed outwards, towards the brake drum 30, and respectively pulled inwards, away from the brake drum 30.
  • the expander elements 330 comprise a spring 33, the springback factor of which af- fects the drum elements 31a, 32a and the brake shoes 31, 32, pushing them further away from each other, i.e. outwards.
  • the expander elements 330 also comprise two flat connecting elements, i.e. a first connecting element 35 and a second connecting element 36. They are arranged adjacently on top of each other in between the other ends of the drum elements 3Ia 5 32a.
  • the first connecting element 35 is at the other side attached to the first drum element 31a
  • the second connecting element 36 is at the other side attached to the second drum element 32a, from which the connecting elements of the drum elements are projected towards each other.
  • Both connecting elements 35, 36 are respectively provided with a first slot 37 and a second slot 38, which are placed at mutually matching points and transversally through the brake drum 3, against the vertical plane drawn through the brake drum 3. Moreover, they are essentially arranged in the direction of the central axis of the drum brake 3, said central axis being perpendicular to said vertical plane.
  • the first slot 37 is an essentially rectangular, straight slot with a constant width, being placed at essentially right angles to the vertical plane drawn through the center of the drum brake 3, and at the same time parallel with the central axis of the brake drum.
  • the second slot 38 is an expanding, wedge-like slot, for instance triangular, and it is at least on one side placed at an inclined angle against the vertical plane drawn through the center of the drum brake 3.
  • the second slot 38 is at the first end wider than at the second end, and it is arranged to expand from the first end towards the second end.
  • the expander elements 330 also comprise a pin 39 or a corresponding control element, which is arranged to proceed essentially vertically in both slots 37, 38 of the connecting elements 35, 36, and to affect the position of the drum elements 31a, 32a and of the brake blocks 31, 32 through the connecting elements 35, 36.
  • the pin 39 is moved by means of the motion bar 21 of the power unit 20 in the slots 37, 38, preferably from one end C to the other end D, when the position of the brake shoes 31, 32 of the drum brake 3 should be adjusted.
  • An electromechanic parking brake arrangement functions as follows.
  • the first relay 41 of the first circuit 40 of the control unit 4 is released, i.e. its control winding 41a affects the first switch 41b and the second switch 41c, and the modes of these are changed.
  • the first switch 41b is opened and the second switch 41c is closed, so that the first condensator 421 is discharged, at least partly, through the solenoid 201.
  • the first condensator 421 is charged by the voltage from the DC power supply 7.
  • the discharging of the first condensator 421 through the solenoid creates a driving pulse, and as a consequence, the solenoid 201 drives, and its motion bar 21 is shifted from the position A to the position B, i.e. for the length of the impact defined for it.
  • the motion bar 21 in turn shifts the expander elements 330 of the drum brake 3 in the slots 37, 38 of the pin 39 from the position C to the position D ( Figures 2 A and 2B), and as a result, the spring 33a is released to press the brake shoes 31, 32 against the brake drum 30, whereafter the possible rotary motion of the wheel is stopped, and the wheel is not free to rotate anymore.
  • the parking brake is in operation.
  • the parking brake of which is set to work in the above described manner, should be moved, it is desirable that the parking brake is switched off before the moving operation. This is particularly advantageous when the vehicle is moved on its own wheels by pulling or pushing.
  • the parking brake is in operation.
  • the DC power supply 7 is in condition and functions normally, its voltage is switched on, for example by a suitable switch, i.e. to affect the solenoid control unit 4.
  • the first relay 41 of the first circuit 40 functions, and its control winding 41a drives the first switch 41b and the second switch 41c, and these switch modes.
  • the first switch 41b is closed and the second switch 41c is opened, so that the first condensator 421 is charged from the DC power supply 7.
  • the first relay switch 41c is advantageously provided with a slow-motion function, in which case the voltage of the DC power supply 7 is therethrough momentarily fed to the solenoid 201, particularly in between the poles 20a, 20b thereof, in which case the solenoid 201 receives a driving pulse.
  • the motion bar 21 of the solenoid 201 is shifted from the position B back to the position A, and respectively the pin 39 of the expander ele- ments 330 of the drum brake 3 in the slots 37, 38 is shifted from the position D to the position C, the brake shoes 31, 32 are released from the brake drum 30, and the parking brake is not in operation anymore.
  • Said slow-motion function is not necessarily required, if the condensator 421 is replaced by a battery.
  • the control unit 4 of the power unit is provided with a switch, such as a press button switch, by which the second pole 72 of the DC power supply 7 is connected to the first pole 20b of the solenoid.
  • the first pole 71 of the DC power supply 7 is connected to the second pole 20a of the solenoid.
  • the control unit 4 of the power unit is provided with a second circuit 50, which is utilized for canceling the operation of the parking brake.
  • This second circuit 50 also functions in a case where the DC power supply 7 is not in condition and does not function normally. In this kind of mode, a sufficiently high voltage is not obtained in the DC power supply 7 for controlling the first circuit 40 of the control unit 4.
  • the second circuit 50 of the control unit 4 functions as follows. When the parking brake should be released and the wheel should again be made to rotate, the switch 52 is closed. If the second circuit 50 only includes the series circuit of a second condensator 511 and the switch 52, the charge of the condensator is discharged to the solenoid 201, and this receives a driving pulse.
  • the condensator 511 is first discharged through the control winding thereof, in which case the modes of the first switch 53b and the second switch 53c are changed, whereafter the condensator is discharged through the second switch 53b to the solenoid 201.
  • the second relay 53 it is possible for example to reduce the losses of the circuit and to use a small switch 52.
  • the power unit 20 is realized by means of a spindle motor 202.
  • the spindle motor 202 comprises an electric motor that is preferably provided with a gear, and a screw and nut combination.
  • the screw and nut combination changes rotary motion to linear motion, which is connected through the spindle to the motion bar 21.
  • the allowed linear motion i.e. impact length, can be defined as an impact of the spindle motor, and in the parking brake arrangement according to the invention, this is for example 25 - 50 mm.
  • the spin- die motor 202 is preferably provided with integrated end borders, in which case the linear motion is always stopped at the end A, B of the motional range.
  • the next driving pulse or signal makes the spindle motor 202 function in the opposite motional direction, and to shift the motion bar 21 back to the position that preceded the previous position.
  • the operation essentially corresponds to the operation of the double function solenoid 201 described above.
  • an adjusting element 6 in between the motion bar 21 and drum brake 3 of the power unit 20; 201, 202, particularly in between the expander elements 330, there is arranged an adjusting element 6.
  • the adjusting element 6 is a motion converter 61, by means of which both the impact length and direction of the motion bar 21 of the power unit 20; 201, 202 can be matched with the length of the slots 37, 38 of the connecting elements 35, 36 of the expander elements 330 and with the length of the trajectory of the pin 39.

Abstract

The invention relates to an electromechanic parking brake arrangement for an electrically driven vehicle that is provided with a DC power supply (7), such as a battery. The parking brake arrangement (1) comprises an electromagnetic actuator (2) and a drum brake (3) that is fitted in connection with the vehicle wheel. According to the invention, the electromagnetic actuator (2) in the electromechanic parking brake arrangement is a linear power unit (20), the motion bar (21) whereof has a first position (A) and a second position (B), between which positions the motion bar (21) can be moved by sending an electric control signal to the power unit; said motion bar (21) of the power unit is connected to the expander elements (330) of the drum brake (3), so that when the power unit bar is in the first position (A), the two brake shoes (31, 32) of the drum brake (3) are in the rest position, where the drum brake is not in operation, and in the second position (B), the two brake shoes (31, 32) of the drum brake are in the working position, placed against the inner surface of the brake drum, in which case the drum brake is in operation. The electromechanic brake arrangement also comprises a control unit (4) of the power unit, said control unit being provided with a first circuit including a first relay and a first reserve power supply that is connected, through the relay switch, to the power unit, when the voltage of the DC power supply over the relay control winding is drastically dropped, in which case the motion bar (21) of the power unit (20) is shifted from the first position (A) to the second position (B), and the brake shoes (31, 32) are shifted, by means of the motion bar, by the expander elements (330), to the working position, and the parking brake begins to function.

Description

Electromechanic parking brake arrangement
The invention relates to an electromechanic parking brake arrangement according to the preamble of claim 1. In the prior art there is known, from the US patent publication 2006/0278477, an electromechanic parking brake utilizing a drum brake fitted in a wheel. An electromechanic actuator, which is an electric motor, operates the drum brake in order to achieve a braking effect. For this purpose, the expander elements of the brake shoes are provided with a screwing tap, and the electric motor is respectively provided with a spiraling gear wheel, these two being arranged to be mutually effective. By using the electric motor in one direction, the expander elements of the brake shoes function so that the brake shoes are made to be turned outwards and pressed against the brake drum. Now the parking brake is in operation, and the wheel cannot rotate. Respectively, when using the electric motor in the opposite direction, the expander elements of the brake shoes function so that the brake shoes are turned inwards and released from the brake drum. The parking brake is not in operation anymore, in which case the wheel is again free to rotate.
A drawback with the above described electromechanic parking brake is that in order to function appropriately, it always requires a power supply. Another drawback is that owing to its structure, the parking brake functions relatively slowly.
Yet another drawback with the above described electromechanic parking brake is that it includes many different elements. Therefore it is expensive to manufacture, and in addition, malfunctions may easily occur. The object of the invention is to eliminate the drawbacks connected to the above described electromechanic parking brake arrangement. Another object of the invention is to realize a new electromechanic parking brake arrangement that is particularly suited in light, electrically driven vehicles.
The electromechanic brake arrangement according to the invention is characterized by what is set forth in claim 1. The dependent claims represent preferred embodiments of the invention. An electromechanic parking brake arrangement according to the invention for a vehicle, particularly an electrically driven vehicle, said vehicle being provided with a DC power supply, such as a battery, comprises an electromagnetic actuator and a drum brake that is arranged in connection with one or several wheels of the vehicle; said arrangement further comprises a brake drum, two brake shoes and their expander elements; said brake shoes are fitted symmetrically in the brake drum, and said actuator is used for manipulating the expander elements and the brake shoes.
According to the invention, the electromagnetic actuator in the electromechanic parking brake arrangement is a linear power unit, the motion bar of which has two positions, a first position and a second position, and the motion bar can be shifted between said positions by sending an electric control signal to the power unit; further, the motion bar is connected to the drum brake expander elements, so that when the motion bar is in the first position, the two brake shoes of the drum brake are in the rest position, so that the drum brake is not in operation, and in the second posi- tion, the two brake shoes of the drum brake are in the working position, pressed against the brake drum, in which case drum brake is in operation; the electromechanic brake arrangement comprises a control unit of the power unit, having a first circuit, including a first relay and a first electric reserve power supply that is connected, through a relay switch, to the power unit, when the voltage of the DC power supply over the relay control winding is drastically dropped, and as a consequence, the power unit receives a control signal, in which case the motion bar of the power unit is shifted from the first position to the second position, and by means of the motion bar, by the expander elements, the brake shoes are shifted to the working position, and the parking brake begins to function. In a preferred embodiment of the invention, the linear power unit is a double function solenoid.
In a preferred embodiment of the invention, the linear power unit is a spindle motor.
In a preferred embodiment of the invention, the first reserve power supply is a first condensator that is charged from a DC power supply during the normal operation of the vehicle, and the electric charge stored in said condensator is discharged through the relay switch and the power unit, when the voltage of the DC power supply over the relay control winding is drastically dropped.
In a preferred embodiment of the invention, the control unit of the power unit also has a second circuit, including a second electric reserve power supply and a switch, which are coupled in series in between the first pole of the DC power supply and the first pole of the power unit, where the second pole of the power unit is connected to the first pole of the DC power supply, and the switch is supposed to connect the first pole of the power unit to the reserve power supply, in which case the power unit receives a second control signal, and the motion bar is shifted from the second position to the first position, and by means of the motion bar, by the expander elements, the brake shoes of the drum brake are shifted to the rest position, and the wheel is thus released to rotate.
In a preferred embodiment of the invention, the second reserve power supply is a second condensator that is charged from a DC power supply during the normal operation of the vehicle; now the second pole of the power unit is connected to the first pole of the DC power supply, and the switch is supposed to connect the first pole of the power unit to the condensator, so that the charge stored in the condensator is discharged through the power unit, in which case the power unit receives a second control signal, and the motion bar is shifted from the second position to the first position, and by means of the motion bar, by the expander elements, the brake shoes of the drum brake are shifted to the rest position, and the wheel is thus released to rotate.
In a preferred embodiment of the invention, the second circuit of the control unit of the power unit also includes a second relay, the control winding of which is coupled in series with the switch, and these are together coupled in series with a second reserve power supply in between the first pole of the DC power supply and the first pole of the power unit, and the reserve power supply is connected, through a relay switch, to the power unit, when the switch is switched off; as a consequence, the motion bar is shifted from the second position to the first position, and by means of the motion bar, by the expander elements, the brake shoes of the drum brake are shifted to the rest position, and the parking brake is released.
An advantage of the invention is that it is mechanically simple, economical to manufacture and easy to maintain. A particular advantage of the invention is that it functions, even if the voltage in the DC power supply of the vehicle, such as battery, were clearly dropped with respect to its normal value, and electric power could not be obtained therefrom. Thus it is an advantage of the invention that the power unit is made to function without an immediate cooperation of a power supply. Thus it is not necessary for the power supply to function or to be able to generate sufficiently electric power for driving the power unit.
Another remarkable advantage of the invention is that the parking brake arrangement also functions as an emergency brake, when the electric motors serving as the vehicle driving motors loose the supply voltage obtained from the DC power supply. When the supply of power to the electric driving motors, particularly servomotors, is for one reason or another interrupted, their electromagnetic brake power is vanished. At the same time, however, the power unit receives a driving pulse from the first condensator of the first circuit of the control unit. The motion bar of the power unit is shifted from the first position to the second position, and by means of the motion bar, by the expander elements, the brake shoes are shifted to the working position, in which case the parking brake begins to function, in this case in the way of an emergency brake.
Yet another advantage of a preferred embodiment of the invention is that the park- ing brake can be released by a simple and easy operation, when the vehicle should be transported, for example by pulling or pushing, away from the parking area. An advantage here is that even in this case, the power unit is made to function without an immediate cooperation of the power supply.
In a preferred embodiment of the invention, the double function linear power unit is realized by a double function solenoid.
In another preferred embodiment of the invention, the double function linear power unit is realized by a spindle motor.
The invention is explained in more detail below, with reference to the appended drawings, where Figure 1 illustrates a solenoid and a solenoid control unit;
Figures 2A and 2B illustrate, in a top-view partial cross-section, the operation of a parking brake arrangement according to the invention, where the parking brake of Figure 2 A is not in operation, and where the parking brake of Figure 2B is in operation; Figure 3 illustrates another parking brake arrangement according to the invention, where the drum brake is viewed from the top, in partial cross-section; Figure 4 illustrates a brake element, i.e. that part of the drum brake that is fitted inside the brake drum, seen at an inclined angle from above; and
Figure 5 is a side-view illustration of the brake element shown in Figure 4. Like reference numbers for like parts are used in the drawings. The electromechanic parking brake arrangement according to the invention is meant for a vehicle, particularly an electrically driven vehicle. This kind of vehicle is provided with a DC power supply 7, such as a battery, from which its electric motors and other electric systems receive their electric power. Most advantageously the electrically driven vehicle is for example an electrically driven, independently mov- able device that is described in the international patent application PCT/FI2007/000096 by the same applicant.
The parking brake arrangement 1 comprises an electromagnetic actuator 2 and a drum brake 3, which is fitted in connection with the vehicle wheel and with the drive motor unit most advantageously arranged therein. Both the actuator 2 and the drum brake 3 are fastened to the wheel support arrangement. The actuator 2 is preferably arranged in connection with the vehicle frame, in the vicinity of the wheel support arrangement.
The drum brake 3 comprises a brake drum 30, two brake shoes 31, 32 and expander elements of the brake shoes 330. The brake shoes 31, 32 are arranged symmetrically inside the brake drum 30. The expander elements of the brake shoes 330 are operated by the electromechanic actuator 2. The brake mechanism comprises at least brake shoes 31, 32 and their expander elements 330. The drum brake 3 is fitted in the hub of the wheel, so that the brake shoes 31, 32, particularly their friction surfaces, can be used for manipulating the brake drum 30 arranged in connection with the wheel and rotating therealong, and particularly the inner surface thereof, when the rotary motion of the wheel should be interrupted, and in this case when the wheel should particularly be locked in a non-rotary position. The structure of the drum brake 3 in itself is known from the prior art. The purpose of the electromagnetic actuator 2 is to operate the expander elements 330 of the drum brake 3, and thereby the brake shoes 31, 32, particularly for achieving a braking function.
According to the invention, in the electromechanic parking brake arrangement, the electromagnetic actuator 2 is provided with a linear power unit 20, including a motion bar 21. In a preferred embodiment of the invention, the power unit 20 is a double function solenoid 201. The motion bar 21 of the linear power unit 20, which in the embodiment described here is a double function solenoid 201, has two positions, a first position A and a second position B, in between which positions the motion bar 21 can be moved by giving the power unit 20 a suitable electric control pulse, such as driving pulse or signal. It is advantageous that by each driving pulse or the like fed into the poles 2Oa5 20b of the power unit 20, the motion bar 21 is moved between said positions A, B. The driving pulse or the like is preferably generated by means of a relatively fast and sufficiently high voltage change between the solenoid poles 2Oa5 2Ob5 as a consequence of which a power pulse or a corresponding sufficiently long power signal is induced in one or several windings of the power unit 20, which signal makes the motion bar 21 move between the positions A5 B.
The motion bar 21 of the solenoid 201 is connected, either directly (cf. Figures 2 A and 2B) or indirectly (cf. Figure 3), to the drum brake 3, particularly to the expander elements 330 of the brake shoes 31, 32. When the motion bar 21 of the solenoid is in the first position A, the two brake shoes 31, 32 of the drum brake 3 are in the rest position, and their friction surfaces are not in contact with the brake drum 30. Now the drum brake 3 is not in operation, and any braking operation directed to the rotary motion of the wheel is not effective. When the solenoid motion bar 21 is in the second position B, the two brake shoes 31, 32 of the drum brake 3 are in the work- ing position, in which case the brake shoes 31, 32, particularly their friction surfaces, rest against the inner surface of the brake drum 30. Now the drum brake 3 is in operation, and the rotary motion of the wheel is stopped owing to the braking function.
The electromechanic brake arrangement according to the invention comprises a control unit 4 of the power unit, provided with a first circuit 40. Said circuit 40 includes a first relay 41 and a first electric reserve power supply 42. In a preferred embodiment, the first reserve power supply 42 is realized by means of a first con- densator 421, as shall be described in the specification below. As an alternative, the reserve power supply 42 is realized by means of a rechargeable battery that is small in size, but sufficient for the use of the power unit 20 as regards the charging capacity.
In the first condensator 421, there is arranged an electric charge from a DC power supply 7. The charging of the condensator 421 is generally realized during the normal operation of the vehicle. This refers to the normal use of the vehicle, where the vehicle is transported and/or used for carrying out the designated tasks. The electric charge stored in the condensator 421 is discharged (at least partly) through the relay switch 41c and the solenoid 20, when the voltage of the DC power supply 7 over the control winding 41a of the relay is cut or is in general drastically dropped. As a consequence, the solenoid 20 receives a driving pulse, and as a result, the solenoid 20 functions so that the motion bar 21 is shifted from the first position A to the second position B. The movements of the motion bar are transmitted to the expander elements 330 of the drum brake 3, by means of which the brake shoes 31, 32 are shifted to the working position, and the parking brake begins to work.
In the first circuit 40, Figure 1, the control winding 41a of the first relay 41 is coupled in between the poles 71, 72 of the DC power supply 7. The first condensator 421 is coupled in between the poles 71, 72 of the DC power supply 7 through the first switch 41b of the relay 41. The first pole 20b of the solenoid 20 and the condensator 421 (its second pole) are mutually coupled through the second switch 41c of the relay 41. The second pole 20a of the solenoid 20 and the condensator 42 (its first pole) are connected to the first pole 71 of the DC power supply 7. In the stand-up mode, the first switch 41b is closed, i.e. electroconductive, in which case the first condensator 421 receives a suitable electric charge from the DC power supply 7. The second switch 41c of the relay 41 is open, i.e. it is not electroconductive. Moreover, it is assumed that the motion bar 21 of the solenoid 20 is in the first position A. When DC the voltage between the poles 71, 72 of the power supply 7 is interrupted or in general drastically dropped, the voltage change first affects the control winding 41a of the relay 41 through the switches 41b, 41c of the relay 41, which change their switching position. Now the first switch 41b is opened and the second switch 41c is closed (illustrated by dotted lines Figure 1). The first switch 41b cuts the current route between the condensator 421 and the second pole 72 of the DC power supply 7, and the second switch 41c of the relay 41 connects the first pole 20b of the solenoid 20 to the condensator 42. Because the second pole 20a of the solenoid 20 is connected to the first pole 71 of the DC power supply 7, the charge stored in the first condensator 421 is discharged (at least partly) through the solenoid 20, and the solenoid receives a first driving pulse. As a consequence, the solenoid 20 functions so that the motion bar 21 is shifted from the first position A to the second position B. The movement of the motion bar 21 is transmitted to the expander elements 330, so that the brake shoes 31, 32 of the drum brake 3 are shifted to the working position, and the parking brake begins to work.
In a second preferred embodiment of the invention, the control unit 4 of the power unit in the electromechanic brake arrangement comprises a second circuit 50, including a second electric reserve power supply 51 and a switch 52. The second re- serve power supply 51 is advantageously realized by means of a second condensator 511, as shall be described below, with reference to the next preferred embodiment. As an alternative, the second reserve power supply 51 is realized by means of a rechargeable battery, for instance a first reserve power supply 42. The second condensator 511 and the switch 52 are coupled in series in between the first pole 71 of the DC power supply 7 and the first pole 20b of the solenoid 20. A suitable electric charge is arranged in the second condensator 511 from the DC power supply 7 (for example during the normal use of the vehicle). The second pole 20a of the solenoid 20 is connected to the first pole 71 of the DC power supply 7. When the first pole 20b of the solenoid 20 is connected to the second condensator 511 of the switch 52, the electric charge stored in the condensator 511 is discharged (at least partly) through the solenoid 20, in which case it receives a second driving pulse. As a consequence, the solenoid 20 functions so that the motion bar 21 is shifted from the second position B to the first position A. The movement of the mo- tion bar 21 is transmitted to the expander elements 330, so that the brake shoes 31, 32 of the drum brake 3 are shifted to the rest position, and the wheel is thus released to rotate and the parking brake is not in operation anymore.
In this second preferred embodiment, the control unit 4 of the second circuit 50 of the power unit also comprises a second relay 53. The control winding 53a of this switch is coupled in series with the switch 52. The control winding 53a and the switch 52 are together coupled in series with the second condensator 511 in between the first pole 71 of the DC power supply and the first pole 20b of the solenoid 20. In the stand-up mode, the second condensator 51 is coupled at the second pole through the second switch 53 c of the relay to the second pole 72 of the DC power supply 7, and at the first pole 71 to the DC power supply 7 in order to obtain the desired electric charge. The electric charge stored in the second condensator 511 is discharged through the first switch 53b of the second relay 53 and through the solenoid 20, when the switch 52 is closed. At the same time, the current route of the condensator 511 to the DC power supply 7 (to its second pole 72) is interrupted by opening the second switch 53c of the second relay 53. The second condensator 511 is first discharged through the control winding 41a, and further, when the relay is in operation, through the first switch 53b of the relay 53. As a consequence of this second driving pulse, the solenoid 20 functions so that the motion bar 21 is shifted from the second position B to the first position A. The movement of the motion bar 21 is transmitted to the expander elements 330, so that the brake shoes 31, 32 of the drum brake are shifted to the rest position, and the parking brake is released. In this embodiment, the first pole 71 of the DC power supply 7 is in positive voltage, and the second pole is in zero, i.e. earth potential. This can also be arranged in another way; the essential factor in this case is that a sufficient voltage prevails between the poles of the DC power supply. The drum brake 3 that is applied in the electromechanic parking brake arrangement according to the invention comprises a brake mechanism including two curved drum elements 31a, 32a and brake shoes 31, 32 arranged in connection with both (cf. Figure 4 and 5). The drum elements 31a, 32a are turnably interconnected at their first end by a hinge pin 34 or a corresponding element. The expander elements 330 belonging to the brake mechanism are arranged in between the other ends of the drum elements 31a, 32a and simultaneously of the brake shoes 31, 32. When viewed in relation to the vertical plane drawn through the center of the drum brake 3, the drum elements 31a, 32a together form a circular ring, and on the circumference of said ring, there is located the hinge pin 34 and, at the distance of 180 de- grees therefrom, the center point of the expander elements 330. By means of the expander elements, the 330 drum elements 31a, 32a and the brake shoes 31, 32 can be pushed outwards, towards the brake drum 30, and respectively pulled inwards, away from the brake drum 30.
The expander elements 330 comprise a spring 33, the springback factor of which af- fects the drum elements 31a, 32a and the brake shoes 31, 32, pushing them further away from each other, i.e. outwards. The expander elements 330 also comprise two flat connecting elements, i.e. a first connecting element 35 and a second connecting element 36. They are arranged adjacently on top of each other in between the other ends of the drum elements 3Ia5 32a. The first connecting element 35 is at the other side attached to the first drum element 31a, and the second connecting element 36 is at the other side attached to the second drum element 32a, from which the connecting elements of the drum elements are projected towards each other.
Both connecting elements 35, 36 are respectively provided with a first slot 37 and a second slot 38, which are placed at mutually matching points and transversally through the brake drum 3, against the vertical plane drawn through the brake drum 3. Moreover, they are essentially arranged in the direction of the central axis of the drum brake 3, said central axis being perpendicular to said vertical plane. The first slot 37 is an essentially rectangular, straight slot with a constant width, being placed at essentially right angles to the vertical plane drawn through the center of the drum brake 3, and at the same time parallel with the central axis of the brake drum. The second slot 38 is an expanding, wedge-like slot, for instance triangular, and it is at least on one side placed at an inclined angle against the vertical plane drawn through the center of the drum brake 3. The second slot 38 is at the first end wider than at the second end, and it is arranged to expand from the first end towards the second end. The expander elements 330 also comprise a pin 39 or a corresponding control element, which is arranged to proceed essentially vertically in both slots 37, 38 of the connecting elements 35, 36, and to affect the position of the drum elements 31a, 32a and of the brake blocks 31, 32 through the connecting elements 35, 36. The pin 39 is moved by means of the motion bar 21 of the power unit 20 in the slots 37, 38, preferably from one end C to the other end D, when the position of the brake shoes 31, 32 of the drum brake 3 should be adjusted.
An electromechanic parking brake arrangement according to the invention functions as follows. When the voltage from the DC power supply 7 is interrupted (or when the voltage in general drops below the preset threshold value), or when it is inten- tionally cut, the first relay 41 of the first circuit 40 of the control unit 4 is released, i.e. its control winding 41a affects the first switch 41b and the second switch 41c, and the modes of these are changed. Now the first switch 41b is opened and the second switch 41c is closed, so that the first condensator 421 is discharged, at least partly, through the solenoid 201. In a normal situation, the first condensator 421 is charged by the voltage from the DC power supply 7. The discharging of the first condensator 421 through the solenoid creates a driving pulse, and as a consequence, the solenoid 201 drives, and its motion bar 21 is shifted from the position A to the position B, i.e. for the length of the impact defined for it. The motion bar 21 in turn shifts the expander elements 330 of the drum brake 3 in the slots 37, 38 of the pin 39 from the position C to the position D (Figures 2 A and 2B), and as a result, the spring 33a is released to press the brake shoes 31, 32 against the brake drum 30, whereafter the possible rotary motion of the wheel is stopped, and the wheel is not free to rotate anymore. The parking brake is in operation.
When an electrically driven vehicle, the parking brake of which is set to work in the above described manner, should be moved, it is desirable that the parking brake is switched off before the moving operation. This is particularly advantageous when the vehicle is moved on its own wheels by pulling or pushing.
Let us assume that the parking brake is in operation. In case the DC power supply 7 is in condition and functions normally, its voltage is switched on, for example by a suitable switch, i.e. to affect the solenoid control unit 4. Now the first relay 41 of the first circuit 40 functions, and its control winding 41a drives the first switch 41b and the second switch 41c, and these switch modes. Now the first switch 41b is closed and the second switch 41c is opened, so that the first condensator 421 is charged from the DC power supply 7. The first relay switch 41c is advantageously provided with a slow-motion function, in which case the voltage of the DC power supply 7 is therethrough momentarily fed to the solenoid 201, particularly in between the poles 20a, 20b thereof, in which case the solenoid 201 receives a driving pulse. As a consequence, the motion bar 21 of the solenoid 201 is shifted from the position B back to the position A, and respectively the pin 39 of the expander ele- ments 330 of the drum brake 3 in the slots 37, 38 is shifted from the position D to the position C, the brake shoes 31, 32 are released from the brake drum 30, and the parking brake is not in operation anymore. Said slow-motion function is not necessarily required, if the condensator 421 is replaced by a battery.
As an alternative, instead of the slow-motion function of the first relay switch 41c, the control unit 4 of the power unit is provided with a switch, such as a press button switch, by which the second pole 72 of the DC power supply 7 is connected to the first pole 20b of the solenoid. The first pole 71 of the DC power supply 7 is connected to the second pole 20a of the solenoid. When the switch is momentarily pressed, the voltage from the DC power supply 7 affects momentarily over the sole- noid and it receives a driving pulse, as a consequence of which the motion bar 21 of the solenoid 201 is shifted from the position B back to the position A, and respectively it affects the expander elements 330 of the drum brake 3, and the parking brake is not in operation anymore.
In a preferred embodiment of the invention, the control unit 4 of the power unit is provided with a second circuit 50, which is utilized for canceling the operation of the parking brake. This second circuit 50 also functions in a case where the DC power supply 7 is not in condition and does not function normally. In this kind of mode, a sufficiently high voltage is not obtained in the DC power supply 7 for controlling the first circuit 40 of the control unit 4. The second circuit 50 of the control unit 4 functions as follows. When the parking brake should be released and the wheel should again be made to rotate, the switch 52 is closed. If the second circuit 50 only includes the series circuit of a second condensator 511 and the switch 52, the charge of the condensator is discharged to the solenoid 201, and this receives a driving pulse. Respectively, if the second cir- cuit 50 also comprises a second relay 53, the condensator 511 is first discharged through the control winding thereof, in which case the modes of the first switch 53b and the second switch 53c are changed, whereafter the condensator is discharged through the second switch 53b to the solenoid 201. Owing to the second relay 53, it is possible for example to reduce the losses of the circuit and to use a small switch 52. When a driving pulse is fed in the solenoid 201, the motion bar 21 is shifted from the position B back to the position A, and it respectively affects the expander elements 330 of the drum brake 3, and the parking brake is not in operation anymore.
In a preferred embodiment of the invention, the power unit 20 is realized by means of a spindle motor 202. The spindle motor 202 comprises an electric motor that is preferably provided with a gear, and a screw and nut combination. The screw and nut combination changes rotary motion to linear motion, which is connected through the spindle to the motion bar 21. The allowed linear motion, i.e. impact length, can be defined as an impact of the spindle motor, and in the parking brake arrangement according to the invention, this is for example 25 - 50 mm. The spin- die motor 202 is preferably provided with integrated end borders, in which case the linear motion is always stopped at the end A, B of the motional range. The next driving pulse or signal makes the spindle motor 202 function in the opposite motional direction, and to shift the motion bar 21 back to the position that preceded the previous position. Thus the operation essentially corresponds to the operation of the double function solenoid 201 described above.
In a preferred embodiment of the invention, in between the motion bar 21 and drum brake 3 of the power unit 20; 201, 202, particularly in between the expander elements 330, there is arranged an adjusting element 6. By means of this, at least the impact length of the solenoid motion bar 21 between the positions A and B can be matched with the length of the slots 37, 38 of the connecting elements 35, 36 of the expander elements 330 and with the length of the trajectory of the pin 39 between the positions C and D.
In a preferred embodiment of the invention, the adjusting element 6 is a motion converter 61, by means of which both the impact length and direction of the motion bar 21 of the power unit 20; 201, 202 can be matched with the length of the slots 37, 38 of the connecting elements 35, 36 of the expander elements 330 and with the length of the trajectory of the pin 39.
The invention is not restricted to the above described embodiment only, but many modifications are possible within the scope of the inventive idea defined in the claims.

Claims

Claims
1. An electromechanic parking brake arrangement for a vehicle, particularly a light electrically driven vehicle, said vehicle being provided with a DC power supply (7), such as battery, and said parking brake arrangement (1) comprising an elec- tromagnetic actuator (2) and a drum brake (3) that is fitted in connection with one or several wheels of the vehicle, said drum brake (3) comprising a brake drum (30), two brake shoes (31, 32) and their expander elements (330), said brake shoes being symmetrically fitted in the brake drum, and said actuator being used for manipulating the expander elements and the brake, characterized in that in the electrome- chanic parking brake arrangement, the electromagnetic actuator (2) is a linear power unit (20), the motion bar (21) of which has two positions, a first position (A) and a second position (B), between which positions the motion bar (21) is movable by sending the power unit an electric control signal; and that the motion bar (21) of the power unit is connected to the expander elements (330) of the drum brake (3), so that when the power unit bar is in the first position (A), the two brake shoes (31, 32) of the drum brake (3) are in the rest position, where the drum brake is not in operation, and in the second position (B), the two brake shoes (31, 32) of the drum brake (3) are in the working position, pressed against the inner surface of the brake drum, in which case the drum brake is in operation; and that the electromechanic brake ar- rangement comprises a control unit (4) of the power unit, said control unit (4) having a first circuit (40) including a first relay (41) and a first electric reserve power supply (42) that is connected, through a relay switch (41c), to a power unit (20), when the voltage of the DC power supply (7) over the relay control winding (41a) is drastically dropped, as a consequence of which the power unit receives a control signal, as a result of which the motion bar (21) of the power unit (20) is shifted from the first position (A) to the second position (B), and by means of said motion bar, by the expander elements (330), the brake shoes (31, 32) are shifted to the working position, and the parking brake begins to function.
2. An electromechanic brake arrangement according to claim 1, characterized in that the first reserve power supply (42) is a first condensator (421) that is charged from the DC power supply (7) during the normal operation of the vehicle, and that the electric charge stored in said first condensator is discharged through a relay switch (41c) and a power unit (20), when the voltage of the DC power supply (7) over the relay control winding (41a) is drastically dropped.
3. An electromechanic brake arrangement according to claim 1 or 2, characterized in that the control unit (4) of the power unit also has a second circuit (50), in- eluding a second electric reserve power supply (51) and a switch (52), which are coupled in series in between the first pole (71) of the DC power supply (7) and the first pole (20b) of the power unit (20), where the second pole (20a) of the power unit (20) is connected to the first pole (71) of the DC power supply (7), and where the switch (52) is supposed to connect the first pole (20b) of the power unit to the reserve power supply (51), in which case the power unit (20) receives a second control signal, according to which the motion bar (21) is shifted from the second position (B) to the first position (A), and by means of the motion bar, by the expander elements (330), the brake shoes (31, 32) of the drum brake (3) are shifted to the rest position, and the wheel is thus released to rotate.
4. An electromechanic brake arrangement according to claim 3, characterized in that the second reserve power supply (51) is a second condensator (511) that is charged from the DC power supply (7) during the normal operation of the vehicle, where the second pole (20a) of the power unit (20) is connected to the first pole (71) of the DC power supply (7), and where the switch (52) is supposed to connect the first pole (20b) of the power unit to the condensator (51), so that the charge stored in the condensator (51) is discharged through the power unit (20), in which case the power unit receives a second control signal, and as a result the motion bar (21) is shifted from the second position (B) to the fist position (A), and by means of the motion bar, by the expander elements (330), the brake shoes (31, 32) of the drum brake (3) are shifted to the rest position and the wheel is thus released to rotate.
5. An electromechanic brake arrangement according to any of the preceding claims, characterized in that the second circuit (50) of the control unit (4) of the power unit also comprises a second relay (53), the control winding (53a) of which is coupled in series with the switch (52), and that these are together coupled in series with a second reserve power supply (51) in between the first pole (71) of the DC power supply and the first pole (20b) of the power unit (20), and that the reserve power supply (51) is connected, through the relay switch (53b), to the power unit (20), when the switch (52) is closed, as a consequence of which the motion bar (21) is shifted from the second position (B) to the fist position (A), and that by means of the motion bar, the expander elements (330) of the drum brake shoes (31, 32) are shifted to the rest position, and the parking brake is released.
6. An electromechanic brake arrangement according to any of the preceding claims, where the drum brake (3) comprises two semicircular drum elements (31a,
32a), in connection with which there are arranged brake shoes (31, 32) that are turn- ably interconnected at their first ends by a hinge pin (34) or the like; and expander elements (330) provided at the other ends of the drum elements (31a, 32a), including a spring (33) that is arranged in between the drum elements (31a, 32a) and at the same time in between the other ends of the brake shoes (31, 32), so that the spring- back factor of the spring (33) affects the brake shoes (31, 32), pressing them away from each other, i.e. outwardly, characterized in that the expander elements (330) also include a first (35) and second connecting element (36), which are arranged in an overlapping fashion and near to each other in between the other ends of the drum elements (31a, 32a), of which the first connecting element (35) is fastened to the first drum element (31a), and the second connecting element (36) is fastened to the second drum element (32a), and that both connecting elements (35, 36) are respectively provided with a first (37) and a second slot (38), said slots being placed at matching locations, transversally through the drum brake, with respect to the vertical plane drawn through the center of the drum brake, and that the first slot (37) is essentially a rectangular, straight slot with a constant width, and the second slot (38) is a wedge-like expanding slot that is at least on one side placed at an inclined angle through the drum brake, with respect to the vertical plane drawn through the center of the drum brake, and that both slots are provided with a pin (39) or a corresponding control element that is moved by solenoids (20), by means of the motion bar (21), in the slots (37, 38), preferably in between the slots ends (C5 D).
7. An electromechanic brake arrangement according to claim 6, characterized in that in between the motion bar (21) of the power unit (20) and the drum brake (3), particularly between the expander elements (330) thereof, there is arranged an adjusting element (6), by means of which at least the impact length of the power unit motion bar (21) can be matched with the length of the slots (37, 38) provided in the connecting elements (35, 36) of the expander elements (330) and with the length of the trajectory of the pin (39).
8. An electromechanic brake arrangement according to claim 6, characterized in that the adjusting element (6) is a motion converter (61), by which both the impact length and direction of the motion bar (21) of the power unit (20) can be matched with the length of the slots (37, 38) provided in the connecting elements (35, 36) of the expander elements (330) and with the length of the trajectory of the pin (39).
9. An electromechanic brake arrangement according to any of the preceding claims, characterized in that the linear power unit (20) is a double function sole- noid (201).
10. An electromechanic brake arrangement according to any of the preceding claims 1—8, characterized in that the linear power unit (20) is a spindle motor (202).
PCT/FI2008/050414 2007-07-06 2008-07-04 Electromechanic parking brake arrangement WO2009007505A1 (en)

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FI20070532A FI119855B (en) 2007-07-06 2007-07-06 Electromechanical parking brake arrangement
FI20070532 2007-07-06

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Cited By (5)

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Publication number Priority date Publication date Assignee Title
US9062728B2 (en) 2013-05-29 2015-06-23 Bendix Spicer Foundation Brake Llc Hinged table brake shoe
FR3030419A1 (en) * 2014-12-23 2016-06-24 Foundation Brakes France Sas ELECTRONIC PARKING BRAKE SYSTEM
US9848532B2 (en) 2012-06-15 2017-12-26 Mauno Keski-Luopa Modular lawn maintenance machine and method
US11044844B2 (en) 2012-06-15 2021-06-29 Mauno Keski-Luopa Maintenance and transportation method, system, and apparatus
CN116006599A (en) * 2022-12-24 2023-04-25 河南科技大学 Novel drum brake energy recovery and electromagnetic auxiliary braking device

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WO2000000374A1 (en) * 1998-06-18 2000-01-06 Permobil Ab Electromechanical brake
DE102007054498A1 (en) * 2006-11-15 2008-05-21 Continental Teves Ag & Co. Ohg Electromechanically operable parking brake such as drum brake, for motor vehicle, has spreader pivot and bearing frame faced with each other so that maximum self reinforcement of brake is effected

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WO2000000374A1 (en) * 1998-06-18 2000-01-06 Permobil Ab Electromechanical brake
DE102007054498A1 (en) * 2006-11-15 2008-05-21 Continental Teves Ag & Co. Ohg Electromechanically operable parking brake such as drum brake, for motor vehicle, has spreader pivot and bearing frame faced with each other so that maximum self reinforcement of brake is effected

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9848532B2 (en) 2012-06-15 2017-12-26 Mauno Keski-Luopa Modular lawn maintenance machine and method
US11044844B2 (en) 2012-06-15 2021-06-29 Mauno Keski-Luopa Maintenance and transportation method, system, and apparatus
US11778942B2 (en) 2012-06-15 2023-10-10 Mauno Keski-Luopa Maintenance and transportation method, system, and apparatus
US9062728B2 (en) 2013-05-29 2015-06-23 Bendix Spicer Foundation Brake Llc Hinged table brake shoe
FR3030419A1 (en) * 2014-12-23 2016-06-24 Foundation Brakes France Sas ELECTRONIC PARKING BRAKE SYSTEM
WO2016102906A1 (en) * 2014-12-23 2016-06-30 Foundation Brakes France Sas Autonomous electric parking brake system
CN116006599A (en) * 2022-12-24 2023-04-25 河南科技大学 Novel drum brake energy recovery and electromagnetic auxiliary braking device
CN116006599B (en) * 2022-12-24 2023-08-01 河南科技大学 Novel drum brake energy recovery and electromagnetic auxiliary braking device

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FI20070532A (en) 2009-01-07
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