ELECTRIC ACTUATOR ASSEMBLY FOR A DRUM BRAKE ASSEMBLY

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to, and the benefit of, U.S.

Provisional Application Serial No. 62/610,981, filed December 28, 2017, the full disclosure of which is incorporated herein by reference in entirety.

BACKGROUND OF INVENTION

[0002] This invention relates in general to drum brake assemblies for automotive vehicles and in particular to an electric actuator assembly for such a drum brake assembly.

[0003] Automotive vehicles are typically equipped with a brake system for slowing or stopping movement of the vehicle in a controlled manner. A common brake system for an automobile or light truck includes a disc brake assembly for each of the front wheels and a drum brake assembly for each of the rear wheels. The brake assemblies are actuated by hydraulic or pneumatic pressure generated when an operator of the vehicle depresses a brake pedal. The brake assemblies may be used to provide service braking, emergency braking, and/or a parking brake function. The structures and operation of these disc brake assemblies and drum brake assemblies are well known in the art

[0004] The typical drum brake assembly includes a brake drum that rotates with the vehicle wheel and a pair of brake shoe and lining assemblies mat are rotationally fixed. The drum brake assembly operates by the brake shoe and lining assemblies being selectively actuated between braking and non-braking positions. In the braking position, the brake shoe and lining assemblies contact and press against the brake drum to slow or otherwise stop rotation of the wheel to provide braking for the vehicle. In the non-braking position, the brake shoe and lining assemblies do not contact the brake drum and allow the wheel to rotate freely. For the drum brake assembly to provide emergency braking, or to provide the parking brake function, an electric actuator assembly may be used to actuate the brake shoe and lining assemblies from the non-braking position to the braking position and/or to support or otherwise maintain the brake shoe and lining assemblies in the braking position.

[0005] The electric actuator assembly actuates the brake shoe and lining assemblies using an electric motor. The electric motor drives a linear translation assembly to selectively displace a gear nut and a spindle either away from or towards each other. When the gear nut and the spindle are displaced away from each other, the brake shoe and lining assemblies are pressed against the brake drum - i.e., the brake shoe and lining assemblies are actuated to the braking position. When the gear nut and the spindle are displaced towards each other, the brake shoe and lining assemblies are released from the brake drum - i.e., the brake shoe and lining assemblies are placed in the non-braking position. Electrical currents drawn by the electric motor are measured for control of the actuator assembly.

[0006] When the spindle is retracted, the gear nut contacts a stop surface or other end stop. This results in an increase in the electrical current The electric motor is then turned off when the electrical current exceeds a threshold value. The contact between the gear nut and the stop surface develops an impact force.

However, the electrical current increases too quickly - i.e., spikes - for the electric motor to be turned off before the impact force may damage the actuator assembly. Thus, it would be desirable to have an electric actuator assembly for drum brake assemblies with a reduced potential of damage when the spindle is retracted.

SUMMARY OF INVENTION

[0007] This invention relates to an electric actuator assembly for use with a drum brake assembly.

[0008] According to one embodiment, an electric actuator assembly for a drum brake assembly may comprise, individually and/or in combination, one or more of the following features: an electric motor with an output shaft, a gear reduction driven by the output shaft, a linear translation assembly having a gear nut and a rotationally fixed spindle, a spring member between the gear nut and the spindle, a connection portion of the linear translation assembly that is configured to selectively actuate and release a brake shoe and lining assembly of the drum brake assembly, and an electrical sensor measuring an electrical current drawn by the electric motor. The gear nut is driven by the gear reduction. The linear translation assembly linearly translates when the gear nut is driven. The electric motor is turned off as a function of the electrical current.

[0009] According to this embodiment, the electric motor is turned off when the electrical current exceeds a threshold value.

[0010] According to this embodiment, the threshold value is less than a second value and the electrical sensor measures the second value when the gear nut contacts a stop surface of the linear translation assembly.

[0011] According to this embodiment, the spring member compresses as the brake shoe and lining assembly is released and the spring member compressing slows a rate at which the electrical current increases. [0012] According to this embodiment, the spring member is outside the gear nut

[0013] According to this embodiment, the spring member is between an end face of the gear nut and a head portion of the spindle.

[0014] According to this embodiment, the spring member is inside the gear nut

[0015] According to this embodiment, the spring member is between a base portion of the gear nut and a tip portion of the spindle.

[0016] According to this embodiment the spring member is fabricated from a metal, plastic, or elastomer material.

[0017] According to this embodiment, the electric actuator assembly may further comprise a first axis about which the output shaft rotates and a second axis along which the linear translation assembly translates. The first axis and the second axis are perpendicular.

[0018] According to another embodiment, a drum brake assembly may comprise, individually and/or in combination, one or more of the following features: a brake drum, a brake shoe and lining assembly that is operably displaceable to contact the brake drum, an electric actuator assembly, a drum-in- hat adapter to which the electric actuator assembly is mounted, and a notch in the drum-in-hat adapter in which the electric actuator assembly is inserted in a radial direction. The electric actuator assembly has an electric motor with an output shaft, a gear reduction driven by the output shaft, a linear translation assembly having a gear nut driven by the gear reduction and a rotationally fixed spindle, and a connection portion of the linear translation assembly. The linear translation assembly linearly translates when the gear nut is driven. The connection portion is configured to selectively actuate and release the brake shoe and lining assembly. [0019] According to this embodiment, the drum-in-hat adapter has first and second faces, a side surface defined between the first and second faces, and the notch extends radially inward from title side surface.

[0020] According to this embodiment, the notch has a depth from the side surface.

[0021] According to this embodiment, the drum brake assembly may further comprise a spring member between the gear nut and the spindle and an electrical sensor measuring an electrical current drawn by the electric motor. The electric motor is turned off as a function of the electrical current.

[0022] According to this embodiment, the electric motor is turned off when the electrical current exceeds a threshold value.

[0023] According to this embodiment, the drum brake assembly may comprise a first axis about which the output shaft rotates and a second axis along which the linear translation assembly translates. The first axis and the second axis are perpendicular.

[0024] According to another embodiment, a drum brake assembly may comprise, individually and/or in combination, one or more of the following features: a brake drum, a brake shoe and lining assembly operably displaceable to contact the brake drum, an electric actuator assembly, a drum-in-hat adapter to which the electric actuator assembly is mounted, and a notch in the drum-in-hat adapter. The notch is configured for the electric actuator assembly to be inserted in the notch in a radial direction. The electric actuator assembly has an electric motor with an output shaft, a first axis about which the output shaft rotates, a gear reduction driven by the output shaft, a linear translation assembly having a gear nut and a rotationally fixed spindle, a spring member between the gear nut and the spindle, a second axis along which the linear translation assembly translates, and a connection portion of the linear translation assembly. The gear nut is driven by the gear reduction. The linear translation assembly linearly translates when the gear nut is driven. The connection portion is configured to selectively actuate and release the brake shoe and lining assembly. The first axis and the second axis are perpendicular. The spring member compresses as the brake shoe and lining assembly is released.

[0025] According to this embodiment, the drum brake assembly may further comprise an electrical sensor measuring an electrical current drawn by the electric motor. A position of the gear nut on the spindle is a function of the electrical current The electric motor is turned off when the electrical current exceeds a threshold value. The threshold value is less than a second value. The electrical sensor measures the second value when the gear nut contacts a stop surface of the linear translation assembly.

[0026] According to this embodiment, the drum brake assembly may further comprise an external drive connection port for the electric motor, a housing of the electric actuator assembly having first and second housing parts, and a housing split line between the first and second housing parts. The external drive

connection port is fully within the first housing part. The housing split line is offset from the external drive connection port

[0027] According to this embodiment, the linear translation assembly has a normal screw thread.

[0028] An advantage of an embodiment is an electric actuator assembly with a reduced potential of damage when a spindle of the actuator assembly is retracted. Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] FIG. 1 is a first perspective view of a drum brake assembly having a first embodiment of an electric actuator assembly in accordance with the present invention.

[0030] FIG. 2 is second perspective view of the drum brake assembly of FIG. 1.

[0031] FIG. 3 is an exploded perspective view of the drum brake assembly of FIG. 1.

[0032] FIG. 4 is a section view taken along line 44 of FIG. 2.

[0033] FIG. 5 is a section view taken along line 5-5 of FIG. 3.

[0034] FIG. 6 is a section view taken along line 6-6 of FIG. 5.

[0035] FIG. 7 is a first perspective view of an alternate gear reduction for use with the electric actuator assembly of FIG. 1.

[0036] FIG. 8 is a second perspective view of the alternate gear reduction of FIG. 7.

[0037] FIG. 9 is a section view showing a linear translation assembly of the electric actuator assembly of FIG. 1.

[0038] FIG. 10 is a graph of electrical current drawn by the electric actuator assembly of FIG. 1.

[0039] FIG. 11 is an elevation view of the drum brake assembly of FIG. 1 with an alternate brake drum for use with the drum brake assembly of FIG. 1.

[0040] FIG. 12 is a perspective view of an alternate drum-in-hat adapter for use with the electric actuator assembly of FIG. 1.

[0041] FIG. 13 is a section view of a linear translation assembly of a second embodiment of an electric actuator assembly in accordance with the present invention.

[0042] FIG. 14 is a first perspective view of a third embodiment of an electric actuator assembly in accordance with the present invention.

[0043] FIG. IS is a second perspective view of the electric actuator assembly of FIG. 14.

[0044] FIG. 16 is an elevation view of the electric actuator assembly of FIG. 14.

[0045] FIGS. 17A-17C show an enlarged portion of FIG. 14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] Referring now to FIGS. 1 -4, there is illustrated a drum brake assembly, indicated generally at 100, for a vehicle. The drum brake assembly 100 has an electric actuator assembly, indicated generally at 102. The general structure and operation of the drum brake assembly 100 is conventional in the art Thus, only those portions of the drum brake assembly 100 which are necessary for a full understanding of this invention will be explained and illustrated in detail. Also, although this invention will be described and illustrated in connection with the drum brake assembly 100, it will be appreciated that this invention may be used in connection with other vehicle brake assemblies, if so desired. As illustrated, the drum brake assembly 100 is a drum-in-hat type drum brake assembly.

[0047] The drum brake assembly 100 and electric actuator assembly 102 are scalable and flexible for usage with vehicles of different sizes and classifications. As non-limiting examples, the drum brake assembly 100 and electric actuator assembly 102 may be scaled for use with different sizes of passenger cars, crossover vehicles, sport utility vehicles, light duty trucks, or heavy duty trucks. [0048] The drum brake assembly 100 has first and second brake shoe and lining assemblies 104 A and 104B, respectively, and first and second shoe hold down clips 106A and 106B, respectively. Both an adjuster screw and nut assembly 108 and a lower shoe return spring 110 are operatively connected with the first and second brake shoe and lining assemblies 104 A and 104B,

respectively. The drum brake assembly 100 also has a splash shield 116, first and second shoe hold down pins 118A and 118B, respectively, a drum-in-hat adapter 120, and an adjusting hole cover 122. The drum brake assembly 100 further has first and second upper shoe return springs 126A and 126B, respectively, connecting the first and second brake shoe and lining assemblies 104A and 104B, respectively.

[0049] The first and second brake shoe and lining assemblies 104A and 104B, respectively, are selectively operable between braking and non-braking positions. In the braking position, the first and second brake shoe and lining assemblies 104A and 104B, respectively, contact and press against a brake drum 112 to slow or otherwise stop rotation of a wheel 114 (shown in FIG. 4) to which the brake drum 112 is rotationally fixed. In the non-braking position, the first and second brake shoe and lining assemblies 104A and 104B, respectively, do not contact the brake drum 112 and allow the wheel 114 to rotate freely.

[0050] The drum-in-hat adapter 120 is mounted to an axle case 124 so as to be rotationally fixed. The electric actuator assembly 102 is a separate, self- contained unit mounted to the drum brake assembly 100 - e.g., the drum-in-hat adapter 120. As non-limiting examples, the electric actuator assembly 102 may be bolted or screwed to the drum-in-hat adapter 120.

[0051] Referring specifically to FIG. 4, the electric actuator assembly 102 comprises an electric motor 128, a gear reduction, indicated generally at 130, and a final drive gear nut 132 threaded on a spindle 134. Together, the gear nut 132 and the spindle 134 comprise a linear translation assembly, indicated generally at 136. The linear translation assembly 136 has a normal screw thread between the gear nut 132 and the spindle 134. The electric actuator assembly 102 is in a housing 138. An electrical sensor 140 measures an electrical current drawn by the electric motor 128 from an electrical power supply 142.

[0052] Referring now to FIGS. 5 and 6, the electric actuator assembly 102 and its components are illustrated in detail. The electric motor 128 has an output shaft 144 that rotationally drives an output or bevel gear 146. Alternatively, the bevel gear 146 may be any suitable, high efficiency gear that can convert a rotation torque 148 of the output shaft 144 to the gear reduction 130 at a right angle. As non-limiting examples, a spiral bevel gear, crown gears, hypoid gears, or other types of gears with intersecting shafts may be used in place of the illustrated bevel gear 146. As a further non-limiting example, a type of gear with non-intersecting shafts (other than a worm gear as worm gears have low

efficiency) may be used in place of the illustrated bevel gear 146. The rotation torque 148 is illustrated as a counterclockwise torque in FIG. 5. One skilled in the art will recognize the rotation torque 148 will be clockwise or counterclockwise in FIG. 5 depending on which direction the electric motor 128 is operated.

[0053] The bevel gear 146 in turn drives a bevel input side ISO of a first reduction gear 1S2. The first reduction gear 1S2 then drives a second reduction gear 1S4, which in turn drives a third reduction gear 156. Although the gear reduction 130 is illustrated as three reduction gears - i.e., the first, second, and third reduction gears 1S2, 1S4, and 1S6, respectively - the gear reduction 130 may alternatively have more or less than three reduction gears. The third reduction gear 1S6 drives an idler gear 158 that then drives the gear nut 132. [0054] The first, second, and third reduction gears 152, 154, and 156, respectively, as well as the idler gear 158 are spur or helical gears. The first, second, and third reduction gears 152, 154, and 156, respectively, and the idler gear 158 are rotationally mounted or otherwise supported by pins 160 - i.e., the first, second, and third reduction gears 152, 154, and 156, respectively, and the idler gear 158 rotate on the pins 160. The gear reduction 130, as well as the idler gear 158, are between the electric motor 128 and the gear nut 132 - i.e., the gear reduction 130 is not at the electric motor 128 and the gear nut 132 is not driven by a worm gear at an end of an output shaft from the gear reduction 130.

[0055] The electric motor 128 is on a first axis 162. The output shaft 144 extends along, and rotates on or about, the first axis 162. The gear reduction 130 extends along a second axis 164 (the section line 6-6 in FIG. 5 is cut along the second axis 164). The first axis 162 and the second axis 164 are perpendicular such that the electric motor 128 is mounted vertically relative to the drum brake assembly 100 in its installed position. Thus, the electric actuator assembly 102 is interchangeable between the drum brake assemblies 100 for "left hand" and "right hand" positions or sides of the vehicle. The left hand and right hand positions for the drum brake assembly 100 are industry standard and known to those skilled in the art For example, the left hand and right hand positions may be at opposite ends of a single axle. As illustrated, the electric motor 128 is vertically above the gear reduction 130. Alternatively, the electric motor 128 may be mounted vertically below the gear reduction 130.

[0056] Additionally, the pins 160 are perpendicular to the second axis 164. As illustrated, the pins 160 are in a single plane, although such is not necessary. The plane having the pins 160 is perpendicular to the first axis 162.

[0057] The spindle 134 is rotationally fixed while permitted to translate along a third axis 166. As the gear nut 132 is rotated by the idler gear 1S8, the gear nut 132 and the spindle 134 translate or otherwise displace in opposite directions along the third axis 166. The third axis 166 is perpendicular to the first axis 162 and the second axis 164. As illustrated, the third axis 166 is also in the plane with the pins 160, although such is not necessary. As the spindle 134 and a first connection portion 168 move in a first direction 170, the gear nut 132 and the second connection portion 172 move in a second direction 174, wherein the second direction 174 is opposite the first direction 170. Movement of the spindle 134 in the first direction 170 actuates or applies the first brake shoe and lining assembly 104A against the brake drum 112 and movement of the gear nut 132 in the second direction 174 actuates or applies the second brake shoe and lining assembly 104B against the brake drum 112. Conversely, movement of the spindle 134 in the second direction 174 releases the first brake and shoe lining assembly 104A from the brake drum 112 and movement of the gear nut 132 in the first direction 170 releases the second brake and shoe lining assembly 104B from the brake drum 112.

[0058] The linear translation assembly 136 has the first connection portion 168 of the spindle 134 that operably connects the spindle 134 with the first brake shoe and lining assembly 104A. The linear translation assembly 136 also has the second connection portion 172 of title gear nut 132 that operably connects the gear nut 132 with the second brake shoe and lining assembly 104B. Each of the first and second connection portions 168 and 172, respectively, are U-shaped, notched, or otherwise shaped to prevent rotation of the spindle 134 when the gear nut 132 is rotated. That is, the shape of the first connection portion 168 rotationally fixes the first connection portion 168 to the first brake shoe and lining assembly 104A and the shape of the second connection portion 172 rotationally fixes the second connection portion 172 to the second brake shoe and lining assembly 104B. The shape of the first and second connection portions 168 and 172, respectively - i.e., non-rotation of the spindle 134 - provide a spread lock function for the drum brake assembly 100.

[0059] Alternatively, one or both of the first or second connection portions 168 or 172, respectively, may be rotationally fixed to the first or second brake shoe and lining assembly 104 A or 104B, respectively, by other than the shape of the first or second connection portions 168 or 172, respectively. As a non-limiting example, the first or second connection portions 168 or 172, respectively, may have a pin connection to the first or second brake shoe and lining assembly 104A and 104B, respectively.

[0060] A bevel spring pack 176 is positioned between the gear nut 132 and the second connection portion 172. The bevel spring pack 176 takes up slack in the linear translation assembly 136. The bevel spring pack 176 compresses when the gear nut 132 moves in the second direction 174.

[0061] Referring now to FIGS. 7 and 8, there is illustrated an alternate gear reduction 130' for the electric actuator assembly 102. The alternate gear reduction 130' includes an additional idler gear 178 between the first reduction gear 1S2 and the second reduction gear 154. The additional idler gear 178 takes up a distance between shafts of the first and second reduction gears 152 and 154, respectively. There is a crown gearing between the output gear 146 and the first reduction gear 152, helical gearings between the first reduction gear 152 and the additional idler gear 178 and also between the additional idler gear 178 and the second reduction gear 154, and a helical gearing between the second reduction gear 154 and the third reduction gear 156. FIG. 7 further shows a housing split line 180 for the housing 138. [0062] Referring now to FIG. 9, there is illustrated the linear translation assembly 136 in detail. The gear nut 132 has an annular end face 182. The spindle 134 has a stem portion 184 and a head portion 186 with an annular underside. Positioned between the end face 182 and the head portion 186 is a spring member 188. As such, the spring member 188 is between the gear nut 132 and the spindle 134 while being outside the gear nut 132.

[0063] When the first and second brake shoe and lining assemblies 104 A and 104B, respectively, are released from the brake drum 112 - i.e., the spindle 134 moves in the second direction 174 and the gear nut 132 moves in the first direction 170 - the spring member 188 is compressed between the end face 182 and the head portion 186. As a result, movement of the gear nut 132 and the spindle 134 towards each other is slowed, damped, or otherwise limited by the spring member 188. Also as a result, a loaded end stop is established for the linear translation assembly 136. As illustrated, the spring member 188 is a Belleville washer type spring. Alternatively, the spring member 188 may be other than as illustrated. As non-limiting examples, the spring member 188 may be fabricated from metal, plastic, or elastomer material.

[0064] Referring now to FIG. 10, there is illustrated an electrical current 190 expected to be drawn by the electric motor 128 when the spindle 134 moves in the second direction 174 and the gear nut 132 moves in the first direction 170. The electrical current 190 is measured by the electrical sensor 140. The spring member 188 slowing movement of the gear nut 132 and the spindle 134 towards each other (by the spring member 188 compressing) results in a slower rate of increase for the electrical current 190.

[0065] When the electrical current 190 exceeds a threshold value 192, the electric motor 128 is turned off. A position of the gear nut 132 on the spindle 134 is proportional to the electrical current 190 when the electrical current 190 is less than the threshold value 192 - i.e., the position of the gear nut 132 on the spindle 134 is a function of the electrical current 190. Thus, the electric motor 128 may be turned off as a function of the position of the gear nut 132 on the spindle 134.

[0066] The electrical current 190 also has a second value 194 when the gear nut 132 first contacts or strikes a stop surface or other end stop 196 of the linear translation assembly 136. The threshold value 192 is less than the second value 194. For a time period after the gear nut 132 first contacts the stop surface 196, the electrical current 190 increases at a greater rate than before the gear nut 132 contacts the stop surface 196. As illustrated, the stop surface 196 is provided as formed in the housing 138. Alternatively, the stop surface 196 may be otherwise provided. As a non-limiting example, the stop surface 196 may be provided on the spindle 134.

[0067] As discussed, the electric motor 128 is turned off when the electrical current 190 exceeds the threshold value 192. The threshold value 192 is set or otherwise calibrated such that the electric motor 128 is turned off before the gear nut 132 would contact the stop surface 196.

[0068] For comparison, FIG. 10 also includes a second electrical current 198 shown by a dashed line. The second electrical current 198 would be expected to be drawn by the electric motor 128 when the spindle 134 and the gear nut 132 move towards each other with the spring member 188 omitted. Without the spring member 188, the second electrical current 198 increases starting at a later time, when the gear nut 132 would first contact the stop surface, and at a greater rate than the electrical current 190. The second electrical current 198 spikes or otherwise rapidly increases when the gear nut 132 contacts the stop surface 196.

[0069] Referring now to FIG. 11 , there is illustrated the drum brake assembly 100 with an alternate brake drum 112'. The alternate brake drum 112' is configured for a dual rear wheel arrangement of two adjoining wheels and tires - i.e., a "dually" wheel configuration common for heavy duty pickup trucks.

[0070] Referring now to FIG. 12, there is illustrated an alternate drum-in- hat adapter 120' for use with the electric actuator assembly 102. The alternate drum-in-hat adapter 120' has a first face 200 and a second face 202. A side surface 204 connects the first and second faces 200 and 202, respectively. The alternate drum-in-hat adapter 120' includes a notch, indicated generally at 206, and an axle opening 208. The axle opening 208 extends between the first and second faces 200 and 202, respectively, and is configured for the axle case 124 to extend through. The axle opening 208 is centered about an axle axis 210 along which the axle case 124 extends. The first and second faces 200 and 202, respectively, are substantially perpendicular to the axle axis 210 and the side surface 204 is substantially parallel to the axle axis 210. Between the notch 206 and the axle opening 208 is a bridge portion 212 of the alternate drum-in-hat adapter 120'.

[0071] The notch 206 extends radially inward from the side surface 204 and towards the axle axis 210 in a radial direction 214. The radial direction 214 is perpendicular to the axle axis 210. As illustrated, the notch 206 has first, second, and third sides 216, 218, and 220, respectively, to form a generally rectangular or square shape. Alternatively, the notch 206 may have other than the first, second, and third sides 216, 218, and 220, respectively, and/or other than a generally rectangular or square shape.

[0072] The electric actuator assembly 102 is inserted, mounted, or otherwise installed in the notch 206 by a motion in the radial direction 214. More specifically, the motion in the radial direction 214 may be an initial or primary motion. Preferably, the motion in the radial direction 214 is the only motion for installing the electric actuator assembly 102 in the notch 206. The electric actuator assembly 102 is not inserted, mounted, or otherwise installed in the notch 206 by an initial or primary motion that is parallel to the axle axis 210.

[0073] The notch 206 has a depth 222 from the side surface 204.

Furthermore, a first radial length 224 is from the axle axis 210 to the second side 218 of the notch 206. There is also a second radial length 226 to a first side surface portion 204A on a first side of the notch 206 and a third radial length 228 to a second side surface portion 204B. The first radial length 224 is less than both second and third radial lengths 226 and 228, respectively, to the side surface 204 on either side of the notch 206.

[0074] One or more of the alternate gear reduction 130', alternate brake drum 112', and drum-in-hat adapter 120' may be used in combination with each other for the drum brake assembly 100. Furthermore, one or more of the alternate gear reduction 130', alternate brake drum 112', and drum-in-hat adapter 120' may be used in combination with each other for the drum brake assembly 100 with the spring member 188 omitted.

[0075] Referring now to FIG. 13, there is illustrated a linear translation assembly 336 for use with a second embodiment of an electric actuator assembly, indicated generally at 302, in accordance with the present invention. The electric actuator assembly 302 is a variation of the electric actuator assembly 102 described with reference to FIGS. 1-12. As such, like reference numerals, increased by 200, designate corresponding parts in the drawings and detailed description thereof will be omitted, unless otherwise noted.

[0076] A gear nut 332 has a base portion 430. A spindle 334 has a stem portion 384 with a tip portion 432. Positioned between the base portion 430 and the tip portion 432 is a spring member 388. As such, the spring member 388 is between the gear nut 332 and the spindle 334 while being inside the gear nut 332. As non-limiting examples, the spring member 388 may be a coil or helical type spring. When the gear nut 332 moves in a first direction 370 and the spindle 334 moves in a second direction 374, the spring member 388 is compressed between the base portion 430 and the tip portion 432.

[007η Referring now to FIGS. 14-17, there is illustrated a third

embodiment of an electric actuator assembly, indicated generally at 502, in accordance with the present invention. The electric actuator assembly 502 is a variation of the electric actuator assembly 102 described with reference to FIGS. 1-12. As such, like reference numerals, increased by 400, designate corresponding parts in the drawings and detailed description thereof will be omitted, unless otherwise noted. Preferably, the electric actuator assembly 502 uses the linear translation assembly 136 of FIG. 9, the linear translation assembly 336 of FIG. 13, or some other linear translation assembly with a spring member between a gear nut and a spindle.

[0078] The electric actuator assembly 502 has an external drive connection port, indicated generally at 634. The external drive connection port 634 is for emergency release of a drum brake assembly having the electric actuator assembly 502. The external drive connection port 634 allows connection of an external driving means to mechanically rotate an electric motor 528 and actuate the drum brake assembly. As non-limiting examples, the external driving means may be a manually operated wrench or an external electric motor.

[0079] The electric actuator assembly 502 has a housing 538. In turn, the housing 538 has a housing split line 580. Separate first and second housing parts 538A and 538B, respectively, are joined at the housing split line 580 to form the housing 538. The housing split line 580 is offset from the external drive connection port 634. As such, the external drive connection port 634 is fully within the first housing part S38A.

[0080] Referring now to FIGS. 17A- 17C, the external drive connection port 634 is illustrated in detail. The external drive connection port 634 has a protective outer cap 636. As a non-limiting example, the outer cap 636 may be a rubber cap that fixes over an annular ridge 638 (shown in FIG. 17B). Beneath the outer cap 636 is a dust seal 640. As non-limiting examples, the dust seal 640 may be a plastic or foil seal. Beneath the dust seal 640 is a socket 642 to receive the external driving means.

[0081] In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been described and illustrated in its preferred embodiments. However, it must be understood mat this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.