Abstract
An electromechanical brake actuator (102, 202, 302, 402) for a brake has a cam disc (108, 108, 108, 208, 308, 408) and a brake plunger (114, 214, 314) for actuating a brake lever (358). The cam disc (108, 108, 108, 208, 308, 408) and the brake plunger (114, 214, 314) have contact surfaces in contact with one another for directly transmitting a drive torque. The contact surface of the cam disc (108, 108, 108, 208, 308, 408) extends at a distance r about the pivot point D, which is defined as a function r() with a change rate r() and depends on the angular position of the cam disc (108, 108, 108, 208, 308, 408). The contact surface is configured to effect non-linear transmission between the drive torque of the cam disc (108, 108, 108, 208, 308, 408) and the force transmitted to the brake plunger (114, 214, 314).
Claims
1. An electromechanical brake actuator (102, 202, 302, 402) for a brake, in particular a commercial vehicle disc brake, having: an electric motor (106, 206) for generating a driving torque, a cam disc (108, 108, 108, 208, 308, 408) which is rotatably mounted and operatively connected to the electric motor (106, 206), and a brake plunger (114, 214, 314) configured to move along a plunger axis, for actuating a brake lever (358) of the brake (368), wherein the cam disc (108, 108, 108, 208, 308, 408) and the brake plunger (114, 214, 314) have contact surfaces which bear against each other and slide or roll on each other for directly transmitting the driving torque from the cam disc (108, 108, 108, 208, 308, 408) to the brake plunger (114, 214, 314), wherein the contact surface of the cam disc (108, 108, 108, 208, 308, 408) extends about a pivot point D at a radial distance r defined as a function r() with a rate of change r() and dependent on an angular position of the cam disc (108, 108, 108, 208, 308, 408), and wherein the contact surface is configured in such a way that there is a non-linear transfer between the driving torque of the cam disc (108, 108, 108, 208, 308, 408) and the force transmitted to the brake plunger (114, 214, 314), wherein the radial distance r() is at its minimum for an angular position where =.sub.min and is at its maximum for an angular position where =.sub.max.Math., wherein the rate of change r() is positive at least in certain regions in a first angular range .sub.min.sub.max, and in that the rate of change r() is negative at least in certain regions in a second angular range .sub.max360, wherein, in the first angular range .sub.min.sub.max, the function r() has a first function profile r.sub.1(), and, in the second angular range .sub.max360, has a second function profile r.sub.2() which differs from r.sub.1().
2. The brake actuator (102, 202, 302, 402) as claimed in claim 1, wherein the rate of change is r(.sub.min)=0 at an angular position where =.sub.min.
3. The brake actuator (102, 202, 302, 402) as claimed in claim 2, wherein the function r() has a positive curvature at an angular position where =.sub.min such that r(.sub.min)>0.
4. The brake actuator (102, 202, 302, 402) as claimed in claim 1, wherein the rate of change is r(.sub.max)=0 at an angular position where =.sub.max.
5. The brake actuator (102, 202, 302, 402) as claimed in claim 1, wherein the function r() has a negative curvature at an angular position where =.sub.max such that r(.sub.max)<0.
6. The brake actuator (102, 202, 302, 402) as claimed claim 1, wherein the radial distance r(), at at least one angular position =.sub.p with .sub.max.sub.p360, changes suddenly by a value
7. The brake actuator (102, 202, 302, 402) as claimed in claim 1, wherein the radial distance r() increases strictly monotonically in an angular range .sub.min.sub.max such that r(.sub.min.sub.max)>0.
8. The brake actuator (102, 202, 302, 402) as claimed in claim 1, wherein the radial distance r() decreases strictly monotonically in an angular range .sub.max360 such that r(.sub.max360)<0.
9. The brake actuator (102, 202, 302, 402) as claimed in claim 1, wherein r.sub.1() and r.sub.2() meet at at least one angular position .sub.1,2 at which r.sub.1() and r.sub.2() are smooth.
10. The brake actuator (102, 202, 302, 402) as claimed in claim 9, wherein the angular position .sub.1,2 is a first angular position at which r.sub.1() has a negative curvature, and wherein r.sub.1() and r.sub.2() further meet at a second angular position .sub.2,1 at which r.sub.2=r.sub.1 and r.sub.1() has a positive curvature.
11. The brake actuator (102, 202, 302, 402) as claimed in claim 1, wherein r.sub.1() and r.sub.2() meet at at least one angular position .sub.1,2 at which r.sub.1=r.sub.2.
12. The brake actuator (102, 202, 302, 402) as claimed in claim 11, wherein the angular position .sub.1,2 is a first angular position at which r.sub.1() has a negative curvature, and wherein r.sub.1() and r.sub.2() further meet at a second angular position .sub.2,1 at which r.sub.2=r.sub.1 and r.sub.1() has a positive curvature.
13. The brake actuator (102, 202, 302, 402) as claimed in claim 1, wherein the function r() has a transition function r.sub.3() which meets the first function profile r.sub.1() at a first angular position .sub.1,3, wherein r.sub.1(.sub.1,3)=r.sub.3(.sub.1,3), and which meets the second function profile r.sub.2() at an angular position .sub.3,2, wherein r.sub.2(.sub.3,2)=r.sub.3(.sub.3,2).
14. The brake actuator (102, 202, 302, 402) as claimed in claim 13, wherein the transition function r.sub.3() is a first transition function, and the function r() also has a second transition function r.sub.3(), which meets the first function profile r.sub.1() at a third angular position .sub.3,1, wherein r.sub.1(.sub.3,1)=r.sub.3 (.sub.1,3), and which meets the second function profile r.sub.2() at an angular position .sub.2,3, wherein r.sub.2(.sub.2,3)=r.sub.3(.sub.2,3).
15. The brake actuator (102, 202, 302, 402) as claimed in claim 1, wherein the rate of change is r(.sub.max<.sub.p)=0 in an angular range .sub.max<.sub.p, wherein .sub.max.sub.p0.1.Math.(.sub.max.sub.min).
16. A cam disc (108, 108, 108, 208, 308, 408) for a brake actuator (102, 202, 302, 402), the cam disc being configured to be connected to a driveshaft of an electric motor (106, 206), wherein the cam disc (108, 108, 108, 208, 308, 408) has a contact surface configured to bear against a contact surface of a brake plunger (114, 214, 314) for directly transmitting a driving torque between the cam disc (108, 108, 108, 208, 308, 408) and the brake plunger (114, 214, 314) in such a way that the contact surfaces slide or roll on each other, wherein the contact surface of the cam disc (108, 108, 108, 208, 308, 408) extends about a pivot point D at a radial distance r defined as a function r() with a rate of change r() dependent on the angular position of the cam disc (108, 108, 108, 208, 308, 408), and the contact surface is configured to effect a non-linear transfer between the driving torque of the cam disc (108, 108, 108, 208, 308, 408) and the force transmitted to the brake plunger (114, 214, 314), wherein the radial distance r() is at a minimum at an angular position where =.sub.min and is at a maximum at an angular position where =.sub.max, wherein the rate of change r() is positive at least in certain regions in a first angular range .sub.min.sub.max and the rate of change r() is negative at least in certain regions in a second angular range .sub.max360, wherein, in the first angular range .sub.min.sub.max, the function r() has a first function profile r.sub.1(), and, in the second angular range .sub.max360, has a second function profile r.sub.2() which differs from r.sub.1().
17. An electromechanical brake actuator (102, 202, 302, 402) for a brake, in particular a commercial vehicle disc brake, having: an electric motor (106, 206) for generating a driving torque, a cam disc (108, 108, 108, 208, 308, 408) which is rotatably mounted and operatively connected to the electric motor (106, 206), and a brake plunger (114, 214, 314) configured to move along a plunger axis, for actuating a brake lever (358) of the brake (368), wherein the cam disc (108, 108, 108, 208, 308, 408) and the brake plunger (114, 214, 314) have contact surfaces which bear against each other and slide or roll on each other for directly transmitting the driving torque from the cam disc (108, 108, 108, 208, 308, 408) to the brake plunger (114, 214, 314), wherein the contact surface of the cam disc (108, 108, 108, 208, 308, 408) extends about a pivot point D at a radial distance r defined as a function r() with a rate of change r() and dependent on an angular position of the cam disc (108, 108, 108, 208, 308, 408), and wherein the contact surface is configured in such a way that there is a non-linear transfer between the driving torque of the cam disc (108, 108, 108, 208, 308, 408) and the force transmitted to the brake plunger (114, 214, 314), wherein the radial distance r() is at its minimum for an angular position where =.sub.min and is at its maximum for an angular position where =.sub.max.Math., wherein the rate of change r() is positive at least in certain regions in a first angular range .sub.min.sub.max, and in that the rate of change r() is negative at least in certain regions in a second angular range .sub.max360, wherein the function r() has a transition function r.sub.3() which meets the first function profile r.sub.1() at a first angular position .sub.1,3, wherein r.sub.1(.sub.1,3)=r.sub.3(.sub.1,3), and which meets the second function profile r.sub.2() at an angular position .sub.3,2, wherein r.sub.2(.sub.3,2)=r.sub.3(.sub.3,2).
18. The brake actuator (102, 202, 302, 402) as claimed in claim 17, wherein the transition function r.sub.3() is a first transition function, and the function r() also has a second transition function r.sub.3(), which meets the first function profile r.sub.1() at a third angular position .sub.3,1, wherein r.sub.1(.sub.3,1)=r.sub.3(.sub.1,3), and which meets the second function profile r.sub.2() at an angular position .sub.2,3, wherein r.sub.2(.sub.2,3)=r.sub.3(.sub.2,3).
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) In the drawings,
(2) FIG. 1 shows a first exemplary embodiment of an electromechanical actuator according to the invention in a side view,
(3) FIG. 2 shows the exemplary embodiment of the actuator according to the invention according to FIG. 1 in a further side view,
(4) FIG. 3 shows the exemplary embodiment of the actuator according to the invention according to FIGS. 1 and 2 in a side view in partial section,
(5) FIG. 4 shows a second exemplary embodiment of an actuator according to the invention in a plan view,
(6) FIG. 5 shows a plan view of the actuator according to FIG. 4,
(7) FIG. 6 shows the exemplary embodiment of the actuator according to the invention according to FIGS. 4 and 5 in a view from obliquely above, without the housing,
(8) FIG. 7 shows the exemplary embodiment of the actuator according to the invention according to FIGS. 4-6 in a view from obliquely above,
(9) FIG. 8 shows the exemplary embodiment of the actuator according to the invention according to FIGS. 4-7 in a view in partial section,
(10) FIG. 9 shows the exemplary embodiment of the actuator according to the invention according to FIGS. 4-8 in a side view, without the housing,
(11) FIG. 10 shows the exemplary embodiment of the actuator according to the invention according to FIGS. 4-9 with the housing closed,
(12) FIG. 11 shows a third exemplary embodiment of an actuator according to the invention and a disc brake according to the invention in a side view,
(13) FIG. 12 shows a fourth exemplary embodiment of an actuator according to the invention in a partial axial section,
(14) FIG. 13 shows the exemplary embodiment of the actuator according to the invention according to FIG. 12 in a plan view of the cam disc,
(15) FIG. 14 shows a diagram of the function r() of the radial distance of the contact surface according to a first exemplary embodiment of a cam disc according to the invention in polar coordinates,
(16) FIG. 15 shows a diagram of the function r() of the radial distance of the contact surface according to the first exemplary embodiment of the cam disc according to the invention in Cartesian coordinates,
(17) FIG. 16 shows a diagram of the function r() of the rate of change of the radial distance of the contact surface according to the first exemplary embodiment of the cam disc according to the invention in Cartesian coordinates,
(18) FIG. 17 shows a diagram of the function r() of the radial distance of the contact surface according to a second exemplary embodiment of a cam disc according to the invention in polar coordinates,
(19) FIG. 18 shows a diagram of the function r() of the radial distance of the contact surface according to a second exemplary embodiment of the cam disc according to the invention in Cartesian coordinates,
(20) FIG. 19 shows a diagram of the function r() of the rate of change of the radial distance of the contact surface according to the second exemplary embodiment of the cam disc according to the invention in Cartesian coordinates,
(21) FIG. 20 shows a diagram of the function r() of the radial distance of the contact surface according to a third exemplary embodiment of a cam disc according to the invention in polar coordinates,
(22) FIG. 21 shows a diagram of the function r() of the radial distance of the contact surface according to the third exemplary embodiment of the cam disc according to the invention in Cartesian coordinates,
(23) FIG. 22 shows a diagram of the function r() of the rate of change of the radial distance of the contact surface according to the third exemplary embodiment of the cam disc according to the invention in Cartesian coordinates,
(24) FIG. 23 shows a diagram of the function r() of the radial distance of the contact surface according to a fourth exemplary embodiment of a cam disc according to the invention in polar coordinates,
(25) FIG. 24 shows a diagram of the function r() of the radial distance of the contact surface according to the fourth exemplary embodiment of the cam disc according to the invention in Cartesian coordinates,
(26) FIG. 25 shows a diagram of the function r() of the rate of change of the radial distance of the contact surface according to the fourth exemplary embodiment of the cam disc according to the invention in Cartesian coordinates,
(27) FIG. 26 shows a diagram of the function r() of the radial distance of the contact surface according to a fifth exemplary embodiment of a cam disc according to the invention in polar coordinates,
(28) FIG. 27 shows a diagram of the function r() of the radial distance of the contact surface according to the fifth exemplary embodiment of the cam disc according to the invention in Cartesian coordinates, and
(29) FIG. 28 shows a diagram of the function r() of the rate of change of the radial distance of the contact surface according to the fifth exemplary embodiment of the cam disc according to the invention in Cartesian coordinates.
DETAILED DESCRIPTION OF THE DRAWINGS
(30) FIG. 1 shows an electromechanical actuator 102 with a housing 104. The actuator 102 has an electric motor 106. The driving torque of the electric motor 106 is transmitted to a cam disc 108 via a transmission (compare FIG. 2). The cam disc 108 serves for the non-linear transmission of the rotational movement of the cam disc 108 to a brake plunger 114.
(31) The brake plunger 114 can in particular be deflected linearly in the illustrated direction of the arrows. The brake plunger 114 has a plunger head 112 at its end facing the cam disc 108. This plunger head 112 surrounds a rolling element 110 which is mounted by means of the bearing 116. The rolling element 110 slides on the periphery of the cam disc 108. Transmission of the rotational movement of the cam disc 108 into a linear movement of the brake plunger 114 is obtained herewith. The electromechanical actuator 102 can be connected in particular to a brake (not illustrated) via a connecting section 118.
(32) The already mentioned transmission 119 is shown in detail in FIG. 2. The transmission 119 has a two-stage configuration. The first stage of the transmission 119 is designed as an epicyclic transmission 120. The epicyclic transmission 120 has a ring gear 122, planet gears 124, and a sun gear 126. In a manner known per se, conversion of the quantities of motion of the electric motor 106 takes place in the epicyclic transmission 120. A spur gear 128 is mounted downstream from the epicyclic transmission 120. This spur gear 128 is connected to the epicyclic transmission 120 via a further spur gear (not visible). The spur gear 128 is situated on a shaft 130 to which the cam disc 108 is also attached. The driving torque is thus transmitted from the electric motor 106 via the transmission 119 and the shaft 130 to the cam disc 108. It should be understood that the transmission 119 can according to the invention in principle be arranged around the axis of rotation of the cam disc 108 over the whole 360 in order to satisfy a variety of structural space situations.
(33) A configuration, by way of example, of the cam disc 108 can be seen in FIG. 3. As illustrated in FIG. 3, the plunger 114 is situated in a completely retracted starting position. The radial distance between the rolling element 110 of the plunger head 112 and the axis of rotation of the cam disc 108 is at its smallest here. If the cam disc 108 then rotates counterclockwise, translational movement of the brake plunger 114 takes place because of the shape of the cam disc 108. This is in particular due to the fact that, as the rotation of the cam disc 108 from the starting position increases, the contact angle between the brake plunger 114 and the cam disc 108 relative to the plunger axis becomes smaller.
(34) This has the additional effect that a change in the angle of rotation of the cam disc 108, with such a shape of the cam disc, has the result that in a change in the angle of rotation of the cam disc 108 within a range of small deflections of the brake plunger 114 causes a larger distance to be covered on the sides of the brake plunger 114 with a smaller transmitted braking force, and wherein, in the region of the maximum deflection 114 of the brake plunger, an equivalent change in the angle of rotation of the cam disc 108 entails a smaller deflection of the brake plunger 114 with a higher transmitted braking force.
(35) A second exemplary embodiment of the electromechanical actuator 202 is illustrated in FIG. 4. The actuator 202 again has a housing 204 and an electric motor, downstream from which a transmission is mounted (both components are not illustrated in FIG. 4). A driving torque is transmitted to the cam disc 208 in a known manner. The cam disc 208 again serves to transmit the rotational movement of the drive into a translational movement of the brake plunger 214. The brake plunger 214 has a brake plunger head 212 which surrounds a rolling element 210 which is mounted with the aid of the bearing 216. A camshaft 244 with a cam 242 is arranged on the shaft (not illustrated). The cam 242 is configured by means of the rolling element 240 and the spring guide 238 to activate a spring element 236 which is guided in a spring guide 234 and is fastened in the housing 204. It is here provided that the cam 242 compresses and hence tensions the spring element 236 and stores energy in a first range of movement, and, in a second range of movement, absorbs the energy stored in the spring element 236 and delivers it to the camshaft 244 which is coupled to the cam disc 208. The cam 244 is furthermore configured to define a locking position. Whilst a specific arrangement of the energy storage and delivery parts (cam 242, rolling element 240, spring guide 238, springe element 236, spring bearing 234) is shown in the drawings, it should be understood that these elements can according to the invention in principle be arranged freely about the axis of rotation of the cam disc 208 in order to satisfy specific structural space requirements, for example in the vehicle, as far as possible.
(36) A plan view of the embodiment already known from FIG. 4 is shown in FIG. 5 without the relevant housing. The structure of the transmission 219 can now be taken from FIG. 5. The transmission 219 has the epicyclic transmission 220 as a first stage. A further speed reduction and torque increase take place in the transmission 219 by means of a spur gear 228. Connected downstream from the transmission 219 is the shaft 230 on which the cam disc 208 is fastened.
(37) FIG. 6 shows a side view of the second exemplary embodiment. The structure of the epicyclic transmission 220 can in particular be taken from here. In a manner known per se, it has a ring gear 222 on which the planet gears 224 are arranged. The sun gear 226 is situated at the center of the epicyclic transmission 220.
(38) FIG. 7 shows a side view of the second exemplary embodiment in a partial view in section.
(39) A view in section of the actuator 202 is illustrated in FIG. 8 with a plane of section along the shaft 230. As can be seen from the Fig., the shaft 230 is not formed as the same component as the camshaft 244 but is connected thereto in particular in a force-fitting fashion.
(40) The transmission 219 is exposed in FIG. 9. Supplementary to the already discussed drawings, it can be seen in FIG. 9 that the planet gears 224 are arranged on a plate 250.
(41) FIG. 10 shows the closed housing 204 of the electromechanical actuator 202. The housing 204 has a first housing section 254 and a second housing section 256. The housing sections 254 and 256 are connected to each other by means of the screws 258.
(42) FIG. 11 shows a third exemplary embodiment of an actuator 302 according to the invention and of a disc brake 368 according to the invention in a side view. The operating principle of the disc brake 368 consists in a brake lining 356 being pressed against a brake disc 354 after having crossed an air gap. The friction that occurs brakes a wheel (not illustrated) connected to the brake disc 354. Alternatively, a brake actuator according to one of the remaining exemplary embodiments can be installed in the disc brake 368.
(43) The force required for this is transmitted to the brake lining 356 via the brake lever 358. The brake lever 358 is in turn activated by the brake plunger 314. The latter is activated in a known manner by the cam disc 308.
(44) With regard to the guidance of the brake plunger 314, two alternative brake plunger guides 315, 315 are shown. The straight brake plunger guide 315 serves to guide the brake plunger 314 (in translation) purely linearly.
(45) Alternatively, a curved brake plunger guide 315 can be provided which enables non-linear guidance of the brake plunger 314.
(46) The electromechanical actuator 302 illustrated in FIG. 11 furthermore has a lever 360 which is coupled to the cam disc 308. A spring head 362, which in turn is connected to a spring element 336, is fastened to the lever 360. A bearing 366 is situated at the other end of the spring element 336. The spring element 336 is again configured to deliver energy, depending on the angle of rotation of the lever 360 and hence the cam disc 308, to the spring element 336 such that the latter is compressed and stores energy. Furthermore, the spring element 336 is configured to transmit energy to the lever 360 and the cam disc 308 via the spring head 362 depending on the range of its angle of rotation. Reference is made to the above explanations with regard to the fundamental operating principle. It should be understood that the arrangement consisting of the lever 360 and the corresponding energy storage and delivery parts (spring head 362, bearing 366, spring 336) can according to the invention in principle be placed freely around the cam disc 308.
(47) A further alternative embodiment of this system for storing and delivering energy is illustrated in FIG. 12. An axial track 478 is attached to the cam disc 408. This axial track 478 extends in an axial direction on one side of the cam disc 408 and has different axial extents. A roller bearing 474, which acts on a spring element 436 via a spring head 472, is in contact with the axial track 478. The spring element 436 is mounted fixedly by means of a bearing 470.
(48) When the cam disc 408 rotates, the roller bearing 474 follows the axial track 478 in the axial direction. If the roller bearing 474 thus moves in the direction of the bearing 470, the spring element 436 arranged between the bearing 470 and the spring head 472 is compressed and therefore energy is stored therein.
(49) If, in contrast, the roller bearing 474 moves on such a section of the axial track 478 where the roller bearing 474 moves in the direction of the cam disc 408, the spring element 436 assists the rotational movement of the cam disc 408 and therefore delivers its stored energy to the latter. It should be understood that the axial track 478 can in principle be positioned on both sides of the cam disc 408.
(50) A plan view of such a cam disc 408 provided with an axial track 478 is illustrated in FIG. 13. The axial track 478 is here arranged centered about the axis of rotation of the cam disc 408.
(51) FIGS. 14 and 15 show diagrams of the function r() according to a first exemplary embodiment (FIGS. 1-13) of the cam disc according to the invention.
(52) FIG. 14 shows the function r() in polar coordinates beginning from an angular position =.sub.min which in the present exemplary embodiment corresponds to an angular position of 0.
(53) It is understood that if, for example, .sub.min=0, it is also true that .sub.min=360 because the rotation of the cam disc would start again once 360 has been exceeded. The angular positions and radii shown are given only by way of example and can be adapted or shifted as desired.
(54) The function r() rises strictly monotonically in a first angular range 0270 and falls strictly monotonically in a second angular range 270360.
(55) The function r() has, as shown in particular in FIG. 16, a positive rate of change r() in the first angular range. Subsequently, the radial distance r() increases constantly in the angular range 0270. As shown in particular in FIG. 15, the radial distance r() increases in particular linearly in this angular range.
(56) The radial distance r() decreases strictly monotonically in the angular range 270360 such that the rate of change r() in this range is negative, as also shown in particular in FIG. 16. As shown in particular in FIG. 15, the radial distance in this angular range decreases linearly.
(57) As the function profile of the rate of change r() according to FIG. 16 shows, the rate of change is smooth in an angular range 0270, such that the radial distance r() changes linearly. r()>0 in this angular range such that the radial distance r() increases until the radial distance assumes a maximum value at the angular position =270. At this angular position, a sudden switch in the rate of change, which is not smooth at this point, takes place and it switches from a positive slope with r()0 to a negative slope with r()0. At this point, the contact surface of the cam disc consequently has a kink.
(58) FIGS. 17 and 18 show diagrams of the function r() according to a second exemplary embodiment of the cam disc according to the invention in polar coordinates and Cartesian coordinates, respectively. FIG. 19 moreover shows a diagram of the function r() of the rate of change of the radial distance of the contact surface according to the second exemplary embodiment of the cam disc according to the invention in Cartesian coordinates.
(59) The function r() according to the second exemplary embodiment differs from the function shown in FIGS. 14 and 15 by an angular range .sub.max.sub.p in which the radial distance r() is constant. This range follows the angular position .sub.max such that the maximum radial distance r.sub.max in this range is constant and forms a kind of tolerance range. The radial distance r() is at its maximum in this tolerance range such that the plunger is held in the maximum deflected position and a constant braking force continues to be exerted on the brake disc even in the event of over-rotation of the cam disc.
(60) As shown in particular in FIG. 19, the rate of change r() in an angular range 0270 is positive and falls suddenly at an angular position =270 to a rate of change of r()=0. In this range, the radial distance r() consequently does not change. Following this tolerance range, the rate of change r() falls suddenly such that the rate of change r() is negative and in particular constant and the radial distance r() in this angular range falls linearly.
(61) FIGS. 20 and 21 show diagrams of the function r() according to a second exemplary embodiment of the cam disc according to the invention in polar coordinates and Cartesian coordinates, respectively. FIG. 22 moreover shows a diagram of the function r() of the rate of change of the radial distance of the contact surface according to the second exemplary embodiment of the cam disc according to the invention in Cartesian coordinates.
(62) The function r() according to the third exemplary embodiment differs from the function shown in FIGS. 14 and 15 by an angular range .sub.max.sub.p in which the radial distance r() is constant and a sudden change in the radial distance r() at the angular position =.sub.p. At this angular position, the radial distance r() falls suddenly by a value
(63)
wherein this jump is not shown to scale in FIGS. 20 and 21 which only illustrate an exemplary jump Or. The stored energy can be dissipated quickly and efficiently by such a predefined jump, wherein the load on the brake actuator is relatively low. The process time which is required to return the brake plunger to its starting position is thus reduced.
(64) As shown in particular in FIG. 2, the rate of change r() drops suddenly at the angular position and then rises again suddenly to a value r()0. The rate of change r() is then smooth and in particular constant again in an angular range >.sub.p such that the radial distance r() decreases linearly in an angular range .sub.p360.
(65) FIGS. 23 and 24 show diagrams of the function r() according to a fourth exemplary embodiment of the cam disc according to the invention in polar coordinates and Cartesian coordinates, respectively. FIG. 25 moreover shows a diagram of the function r() of the rate of change of the radial distance of the contact surface according to the fourth exemplary embodiment of the cam disc according to the invention in Cartesian coordinates.
(66) The function r() according to the fourth exemplary embodiment differs from the function shown in FIGS. 14 and 15 by a smooth profile of the rate of change r(). The function profiles r.sub.1() and r.sub.2() meet at an angular position =.sub.p1,2 at which r.sub.1(.sub.p1,2)=r.sub.2(.sub.p1,2) and at an angular position =.sub.p2,1 at which r.sub.2(.sub.p2,1)=r.sub.1(.sub.p2,1). The function profiles r.sub.1() and r.sub.2() thus meet with no kinks such that the plunger slides or rolls smoothly on the contact surface of the cam disc and does not experience any vibration.
(67) The first angular position =.sub.p1,2 here describes an angular position which follows the angular position =.sub.max at which the radial distance r() is at its maximum. The second angular position .sub.p2,1 follows the angular position =.sub.min at which the radial distance is at its minimum. The region of the cam disc in which the radial distance r.sub.2() of the contact surface from the pivot point of the plunger decreases thus merges smoothly and in particular with no kinks into the region of the cam disc in which the radial distance r.sub.1() increases in particular linearly.
(68) As shown in particular in FIG. 25, r() is smooth in the whole angular range.
(69) FIGS. 26 and 27 show diagrams of the function r(v) according to a fifth exemplary embodiment of the cam disc according to the invention in polar coordinates and Cartesian coordinates, respectively. FIG. 28 moreover shows a diagram of the function r() of the rate of change of the radial distance of the contact surface according to the fifth exemplary embodiment of the cam disc according to the invention in Cartesian coordinates.
(70) The function r(v) according to a fifth exemplary embodiment differs from the function shown in FIGS. 14 and 15 in that, at an angular position .sub.1,3<.sub.max the first function profile r.sub.1() meets a transition function r.sub.3(), wherein the transition runs smoothly and in particular with no kinks. r.sub.1(.sub.1,3)=r.sub.3(.sub.1,3) applies at such a transition with no kinks. The second function profile r.sub.2() moreover meets the transition function r.sub.3() at a second angular position .sub.3,2>.sub.max smoothly and likewise with no kinks such that r.sub.2(.sub.3,2)=r.sub.3(.sub.3,2) moreover applies. A second transition function r.sub.3() preferably moreover meets the second function profile r.sub.2 () at a third angular position .sub.max<.sub.2,3<360, wherein the transition runs smoothly and in particular with no kinks. At such a transition with no kinks, r.sub.2(.sub.2,3)=r.sub.3(.sub.2,3). At a fourth angular position .sub.3,1>.sub.min, the second transition function r.sub.3() meets the function profile r.sub.1(), wherein the transition runs smoothly and in particular with no kinks. At such a transition with no kinks, r.sub.1(.sub.3,1)=r.sub.3(.sub.3,1).
(71) Such a transition function enables a smooth function profile of the rate of change of r() according to FIG. 28.
