Parallel Shaft Friction Drag Brake

Abstract

One aspect of the disclosure relates to an actuator system including a rotatable drive shaft and a parallel axis friction brake configured to engage the drive shaft and provide a drag force to the rotatable drive shaft. The parallel axis friction brake further includes a brake housing and a friction assembly having at least one parallel axis shaft and at least one clip pressed onto the at least one parallel shaft with an interference fit. The friction assembly engages the drive shaft and is coupled to the brake housing such that at least a portion of the friction assembly rotates with the rotatable drive shaft to generate the drag force.

Description

[Technical field]

[0001] In many mechanical systems, it is desirable or necessary to add drag. One common application is automotive closure drive systems where an electric motor drives the opening and closing of a tailgate, door, or rear hatch. During manual use, additional drag is required to compensate for variations in the hatch or gate that cannot be countered by potential offsets (parking on an incline, snow loads, and other added loads). However, when moving these doors / gates powered, it is desirable to minimize the drag that the motor must drive. To maintain efficiency, the drag applied to the system must be precisely controlled. This precise drag torque must be maintained over the life of the actuator, including the full range of temperatures and speeds in use. Additionally, these automotive closure applications are highly sensitive to stick-slip. When stick-slip occurs, the user experiences great instability and discomfort when manually moving the gate. Many applications also have limitations in diameter and allowable length, which further limits braking options. Summary of the Invention [Problem to be solved by the invention]

[0002] Several methods of generating drag are known in the art, e.g., friction disks, wrap springs, magnetic hysteresis, etc. Some of these suffer from stick-slip issues, wear and torque degradation over life, temperature dependence of torque, and low torque density. Some solutions involve adding different materials, e.g., carbon fiber elements, but adding components adds cost and complexity to the design. [Means for solving the problem]

[0003] The inventors have also investigated friction clip devices for drag braking, but stick-slip cannot be avoided in typical applications. Friction clip devices are an attractive way to generate drag brakes in electromechanical actuators because of their small footprint and relative simplicity. However, the stick-slip problem needs to be solved, and further inventions are needed.

[0004] The accompanying drawings are included to provide a further understanding of the embodiments, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the detailed description, serve to explain the principles of the embodiments. Other embodiments and many of the intended advantages of the embodiments will be better understood and readily appreciated by reference to the following detailed description. Elements illustrated in the drawings are not necessarily to scale relative to each other. Like reference numerals indicate corresponding like parts. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 illustrates a power actuator system according to one embodiment. [Diagram 2] FIG. 1 illustrates a power actuator system 10 incorporating a friction brake according to one embodiment. [Figure 3A] FIG. 1 illustrates a friction brake according to one embodiment. [Figure 3B] FIG. 1 illustrates a friction brake according to one embodiment. [Figure 4] A graph showing the torque generated as a function of the friction brake angle. [Figure 5A] FIG. 1 illustrates a power actuator system incorporating a parallel axis friction brake according to one embodiment. [Figure 5B] FIG. 1 illustrates a power actuator system incorporating a parallel axis friction brake according to one embodiment. [Figure 6] FIG. 1 is a partial view of a power actuator system with some portions removed, according to one embodiment. [Figure 7] FIG. 1 is a perspective view of a parallel axis friction brake according to one embodiment; [Figure 8] FIG. 1 is a cross-sectional view of a parallel axis friction brake according to one embodiment. [Figure 9] FIG. 2 is an exploded view of a parallel axis friction brake according to one embodiment. [Figure 10] 1 is a graph illustrating torque generated as a function of angle for a parallel axis friction brake according to one embodiment; [Figure 11] FIG. 1 illustrates a parallel axis friction brake according to one embodiment. [Figure 12] FIG. 1 is a cross-sectional view of a parallel axis friction brake according to one embodiment. [Figure 13] FIG. 1 is a perspective view of a parallel axis friction brake with roller clutch bearing according to one embodiment; [Figure 14A] FIG. 1 is an exploded view of a parallel axis friction brake with roller clutch bearings according to one embodiment; [Figure 14B] FIG. 1 is an exploded view of a parallel axis friction brake with roller clutch bearings according to one embodiment; [Figure 15] FIG. 1 is a cross-sectional view of a parallel axis friction brake with roller clutch bearing according to one embodiment; [Figure 16] FIG. 1 is a perspective view of a parallel axis friction brake with an anti-reverse clutch according to one embodiment; [Figure 17] FIG. 2 is an exploded view of a parallel shaft friction brake with anti-backup clutch according to one embodiment; [Figure 18] FIG. 1 is a cross-sectional view of a parallel shaft friction brake with an anti-backup clutch according to one embodiment; [Figure 19] FIG. 1 illustrates a power actuator system incorporating a parallel axis friction brake according to one embodiment. [Figure 20] FIG. 1 illustrates a power actuator system incorporating a parallel axis friction brake according to one embodiment. [Figure 21] FIG. 1 illustrates a power actuator system incorporating a parallel axis friction brake according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the accompanying drawings, there is shown by way of illustration specific embodiments in which the present invention may be practiced. In the detailed description, directional terms such as "top", "bottom", "front", "back", "head", "tail" and the like are used with reference to the orientation of the figures being described. Components of the embodiments can be arranged in many different orientations. As such, the directional terms are used for purposes of explanation and are in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0007] It should be understood that unless specifically stated otherwise, the features of the various exemplary embodiments described herein can be combined with each other.

[0008] FIG. 1 illustrates a power actuator system 10 according to one embodiment. In one embodiment, the power actuator system 10 is an automobile closing drive system that drives the opening and closing of a tailgate 8 on a vehicle or automobile 9. In such a configuration, it is advantageous to provide additional drag to compensate for fluctuations that cannot be countered by the potential counterbalance of the gate 8 in situations such as when the vehicle is parked on a slope or when a snow load is applied to the gate 8. During powered movement of the gate 8, drag on the motor needs to be minimized, and also drag on the system needs to be precisely controlled to maintain efficiency. This precise drag torque needs to be maintained over the life of the actuator, including the full range of temperatures and speeds in use. The power actuator system 10 can be used to control the movement of various moving components on a stationary vehicle, such as side doors, rear hatches, front hoods, windows, power side steps, air dams, etc.

[0009] A variety of mechanisms have been employed to provide the drag force within the power actuator system 10. Such mechanisms include friction disks, wrap springs, magnetic hysteresis, etc. Such mechanisms can be complex, occupy a lot of space, and may not allow for precise control of the drag force applied to the system.

[0010] FIG. 2 illustrates a power actuator system 10 incorporating a friction brake 20 according to one example. In one example, the power actuator system 10 includes an actuator housing 12, an output screw 14, a motor 16, a gearbox 18, a friction brake 20, and a bearing support 22. In operation, the actuator housing 12 is configured as a relatively elongated tubular device that is mounted between a gate and a frame. For example, as shown in FIG. 1, the power actuator system 10 drives the opening and closing of a tailgate 8 for a vehicle 9. The motor 16 powers the gearbox 18, which in turn drives the output screw 14 in a clockwise or counterclockwise direction to alternately open and close the gate attached thereto. The friction brake 20 is coupled to the output screw 14 to provide a drag torque due to its rotation.

[0011] 3 shows the friction brake 20 in further detail. The friction brake 20 includes a clip 30 and a hollow shaft 36, the clip 30 including a base 34 and an arm 32. The base 34 is configured to fit into a slot in the actuator housing 12, thereby preventing relative movement between the clip 30 and the actuator housing 12. The hollow shaft 36 has an inner surface with teeth that engage and rotate with the output screw 14. The hollow shaft 36 is secured within the arm 32 of the clip 30 with an interference fit. As the hollow shaft 36 rotates within the arm 32 of the clip 30, the interference fit creates a drag torque.

[0012] The inventors have found that the friction brake 20 can meet precise torque requirements over a desired life span with relatively little variation with temperature, and has a fairly small and simple footprint in length, making it very cost competitive. However, the inventors have further found that the friction brake 20 will always have an undesirable amount of stick-slip, which is unavoidable.

[0013] FIG. 4 shows the torque generated by the friction brake 20 as a function of angle as the hollow shaft 36 and output screw 14 rotate. A test system was developed to test the torque generated by the friction brake 20 as a function of angle as the hollow shaft 36 and output screw 14 rotate. A compliant element with a relatively large rotational inertial load was added to the test system. At the start of the test, the brake has no relative motion and the compliant element is loaded to the static torque of the friction brake 20 under test. Relative motion is then initiated once the static torque value is reached. In this case, the brake's characteristics and performance will cause it to rotate faster for a short period of time (represented by the nearly vertical line going down in FIG. 4). Inertia in the system and stored energy in the compliant member will cause the brake device to over travel before coming to a stop. The motor will then load the compliant member without moving the brake to restart the cycle. The torque behavior of a friction brake, as a result of the brake's performance characteristics, the system's inertia, and the system's spring rate, produces a choppy, sawtooth torque output known as stick-slip.

[0014] This is an undesirable output characteristic for power actuator systems used to open and close tailgates and doors. Furthermore, many automotive closure applications are very sensitive to stick-slip, which can cause the user to feel very unstable and uncomfortable when manually moving the gate. Many applications also have limitations on diameter and allowable length, which further limits braking options.

[0015] Figure 5A shows a cross-sectional view of a powered actuator system 10 incorporating a parallel axis friction brake 40 according to one embodiment. In Figure 5A, the parallel axis friction brake 40 is used in place of the friction brake 20. In one embodiment, the powered actuator system 10 includes an actuator housing 12, an output screw 14, a motor 16, a gearbox 18, the parallel axis friction brake 40, and a bearing support 22. In one embodiment, the powered actuator system 10 drives the opening and closing of a tailgate 8 for a vehicle 9, as shown in Figure 1.

[0016] In operation, the actuator housing 12 is configured as a relatively elongated tubular device that is mounted between a tailgate 8 and a vehicle 9, and the power actuator system 10 opens and closes the gate 8. A motor 16 powers a gearbox 18, which drives an output screw 14 in a clockwise or counterclockwise direction to alternately open and close the gate 8 attached thereto. A parallel shaft friction brake 40 is coupled to the output screw 14 to provide a counter torque due to its rotation.

[0017] The inventors have surprisingly found that the parallel axis friction brake 40 produces a much improved stick-slip performance, despite generating a higher pressure than the previously described friction brake 20. This was unexpected. Temperature effects were also surprisingly improved. Utilization of the parallel axis friction brake 40 in the power actuator system 10 was not anticipated, as the higher pressures are counterproductive in terms of longevity. However, the smaller diameter of the parallel axis friction brake 40 means that it has less travel per revolution compared to the friction brake 20.

[0018] FIG. 5B illustrates a cross-sectional view of the power actuator system 10 incorporating a parallel shaft friction brake 40, the cross-sectional view showing a radial cross-section of the parallel shaft friction brake 40. In the parallel shaft friction brake 40, a friction assembly 41 is shown engaging the output screw 14 and providing a drag torque by rotation thereof. As clearly shown in FIG. 5B and as will be shown in further embodiments below, the friction assembly 41 has a parallel shaft that is parallel to the output screw 14 and has a smaller gear outer diameter than the output screw 14. Thus, the parallel shaft of the friction assembly 41 rotates faster than the output screw 14. This increases the pressure in the parallel shaft friction brake 40, enhancing operation of the parallel shaft friction brake 40.

[0019] FIG. 6 shows a partial view of the power actuator system 10 with portions removed to better view the parallel shaft friction brake 42 and the output screw 14. In one embodiment, the parallel shaft friction brake 42 includes a brake housing 44, housing tabs 44a, and a friction assembly 47 contained therein. In one embodiment, the output screw 14 includes a splined end 43 and a spur gear 45. In one embodiment, the spur gear 45 is press fit onto the output screw 14 and configured to engage the friction assembly 47. Thus, as the output screw 14 rotates, for example, driven by the splined end 43 engaged to a component within the gearbox 18, the friction assembly 47 provides a precisely controlled drag force to the power actuator system 10, minimizing excess drag on the motor 16. Thus, when the output screw 14 is stationary but is holding a load via the lead screw 14 due to an external force (such as snow load, user applied force, wind force, gravity load from a slope), the friction assembly 47 provides a precisely controlled resistance to the power actuator system 10, ensuring that the system does not move unexpectedly.

[0020] 7-9 show a parallel axis friction brake 50 according to one embodiment. In one embodiment, the parallel axis friction brake 50 includes a first brake housing portion 52a, a second brake housing portion 52b, a center gear 54, a parallel shaft 56, and a ring clip 58. FIG. 7 shows a perspective view of the parallel axis friction brake 50 including the first brake housing portion 52a and the second brake housing portion 52b. FIG. 8 shows a cross-sectional view taken approximately along the center of the parallel axis friction brake 50. FIG. 9 shows an exploded view of the parallel axis friction brake 50.

[0021] The parallel shaft friction brake 50 is configured to be placed in the power actuator system 10 in place of the parallel shaft friction brake 40 of FIG. 5A or in place of the friction brake 20 of FIG. 2. In operation, the splined end 43 of the output screw 14 engages with a center gear 54, which in one embodiment has internal teeth 54a on its inner surface that engage with the external splined teeth of the output screw 14. This causes the center gear 54 to rotate as the output screw 14 rotates. The center gear 54 also has external gear teeth 54b on its outer surface that are configured to engage with a ring clip 58. The ring clip 58 is pressed onto the parallel shaft 56 with an interference fit to form a friction assembly 60. In one embodiment, the parallel shaft 56 has a knurled end 56a (see FIG. 9) that is press-fit into a brake housing opening 62 such that the parallel shaft 56 is secured to the brake housing 52. Because the parallel shaft 56 is fixed to the brake housing 52, a ring clip 58 rotates on the parallel shaft 56 as the center gear 54 and output screw 14 rotate, thereby allowing the parallel shaft friction brake 50 to provide a precisely controlled drag to the system.

[0022] In one embodiment, the brake housing 52 is configured with tabs 66 that can secure the brake housing 52 to the actuator housing 12. In one embodiment, the tabs 66 extend perpendicularly from the first brake housing portion 52a and couple to the gearbox 18, which is in turn secured to the actuator housing 12 (see FIG. 5A). In another embodiment, the housing tabs 44a (see FIG. 6) can extend radially from the brake housing 44 to secure the brake housing 44 directly to the actuator housing 12, preventing them from rotating relative to each other.

[0023] In one embodiment, the parallel shafts 56 of the friction assemblies 60 are oriented within the brake housing 52 so as to be parallel to but radially offset from the center gear 54. FIG. 8 illustrates a parallel axis friction brake 50 that includes two friction assemblies 60, one above and one below the center gear 54 in the illustrated orientation. Thus, the parallel shafts 56 are parallel to the center gear 54. In one embodiment, the friction assemblies 60 include a friction assembly lubricant 60a that surrounds the parallel shafts 56 and the ring clip 58.

[0024] FIG. 9 shows four friction assemblies 60 mounted within the parallel axis friction brake 50. More or fewer friction assemblies can be used. Also in FIG. 9, each friction assembly 60 includes multiple ring clips 58. Both the number of ring clips 58 used within each friction assembly 60 and the number of friction assemblies 60 used in the parallel axis friction brake 50 are proportional to the amount of drag provided to the system by the parallel axis friction brake 50. Thus, both the number of ring clips 58 and the number of friction assemblies 60 used can be adjusted depending on the drag required for a given application.

[0025] One advantage of utilizing friction assemblies parallel to and offset from the center gear 54 is that they provide excellent drag torque characteristics with a relatively short axial profile. A short axial length is advantageous when space is very limited in a given application. In one embodiment, a parallel axis friction brake 50 with a single friction assembly 60 can generate sufficient drag. However, such a single friction assembly 60 configuration may require multiple ring clips 58 to generate the required drag torque. Using multiple ring clips 58 increases the overall width W52 of the required brake housing 52 to accommodate the multiple ring clips 58. In one embodiment, by using two, four, or more friction assemblies 60, a greater drag torque can be generated and fewer ring clips 58 can be used. In this manner, the axial length can be limited and the overall width W52 of the required brake housing 52 can be minimized. By using multiple friction assemblies 60 within the available circumferential space outside the center gear 54 and inside the brake housing 52, the length within the power actuator system 10 required to provide the drag function can be minimized.

[0026] By using the relatively small diameter shaft of the friction assembly to generate the drag torque compared to the relatively large diameter output screw 14 and center gear 54, higher pressures are generated than in previous designs. However, surprisingly, stick-slip performance is also significantly improved. FIG. 10 shows the torque generated in the parallel axis friction brake 50 as a function of angle as the center gear 54 and output screw 14 rotate. The parallel axis friction brake 50 was evaluated in the same test system used for the friction brake 20 shown in FIG. 4. At the start of the test, the brake has no relative motion and the compliant elements are loaded to the static torque of the friction brake 50 under test. Then, when the static torque value is reached, relative motion is initiated. This is the same as in the previous test. In this case, the characteristics and performance of the parallel axis friction brake 50 cause it to start rotating without exhibiting stick-slip. Clearly, stick-slip is substantially avoided in this design, resulting in a relatively smooth drag torque profile.

[0027] 11 and 12 show a parallel axis friction brake 80 according to one embodiment. In one embodiment, the parallel axis friction brake 80 includes a brake housing 82 and a friction assembly 90. The friction assembly 90 includes a friction gear 84, a parallel shaft 86, a clip 88, and a retaining ring 89. The friction gear 84 is fixed on the parallel shaft 86 and rotates therewith. The clip 88 is pressed onto the parallel shaft 86 with an interference fit to allow them to rotate relative to each other under friction. The retaining ring 89 is pressed onto the parallel shaft 86 to axially secure the friction assembly 90 to the housing 82. A lubricant 92a can be placed into the clip slots 92 to ensure proper lubrication within the friction assembly 90. The parallel axis friction brake 80 can be operated in a similar manner to the parallel axis friction brake 50 described above and can be placed within the power actuator system 10 (like the parallel axis friction brake 40 of FIG. 5A or the friction brake 20 of FIG. 2) to provide similar drag torque characteristics.

[0028] In operation, a drive gear, such as the aforementioned center gear 54, engages the friction gear 84 such that the friction gear rotates with the center gear 54 and output screw 14. The clip 88 is disposed within a clip slot 92 in the brake housing 82. The clip slot 92 has a shape that matches the outer shape of the clip 88, thereby preventing the clip 88 from rotating and securing it relative to the brake housing 82. In this manner, the friction assembly 90 provides a precisely controlled drag force to the power actuator system 10 as the parallel shaft 86 and friction gear 84 rotate within the clip 88, which is held by the brake housing 82.

[0029] In one embodiment, the brake housing 82 is configured with tabs 82a that allow the brake housing 82 to be secured to the actuator housing 12 via the gearbox 18. In one embodiment, the tabs may extend radially, rather than axially, from the outer periphery of the brake housing. For example, tabs 44a extend radially from the outer periphery of the brake housing 44 (see FIG. 6), thereby coupling them to the actuator housing 12 and preventing relative rotation.

[0030] In one embodiment, similar to the parallel axis friction brake 50 previously described, the parallel axis friction brake 80 also allows for the use of a single friction assembly 90. Alternatively, as shown in FIG. 11, four clip slots 92 are provided for additional friction assemblies 90. Similarly, more than four friction assemblies 90 may be used. Additionally, more or fewer clips 88 may be used. Similar to the parallel axis friction brake 50, the use of more friction assemblies 90 and fewer clips 88 helps limit the radial length of the friction brake housing 82, allowing for the use of a relatively compact design.

[0031] As can be seen from the parallel axis friction brake 50 and the parallel axis friction brake 80, different friction elements can be used for the friction assembly 60 (ring clip 58) and the friction assembly 90 (clip 88). Other types of friction elements besides the ring clip 58 and the clip 88 can be placed on the parallel shaft 56 and the parallel shaft 86 to generate the desired torque. For example, a sheet metal band can be wrapped around the parallel shaft to generate the friction assembly in the alternative parallel axis friction brake. The friction assembly in the claimed parallel axis friction brake can provide a relatively smooth drag torque profile without the use of additional springs and without the need for electromechanical actuators.

[0032] 13-15 illustrate a unidirectional parallel axis friction brake 110 according to one embodiment. In one embodiment, the unidirectional parallel axis friction brake 110 includes a first brake housing portion 112a, a second brake housing portion 112b, a center gear 114, and a friction assembly 120. The friction assembly 120 includes a parallel shaft 116 and a ring clip 118. The center gear 114 includes gear teeth 114a and further includes a slot 140 configured to receive a roller 130.

[0033] Figure 13 shows a perspective view of a unidirectional parallel axes friction brake 110 comprising a first brake housing portion 112a and a second brake housing portion 112b. Figures 14A and 14B show exploded views of the unidirectional parallel axes friction brake 110, with Figure 14B being in the opposite direction to Figure 14A and showing both sides of the unidirectional parallel axes friction brake 110. Figure 15 shows a cross-sectional view substantially along the center of the unidirectional parallel axes friction brake 110.

[0034] The unidirectional parallel axes friction brake 110 operates very similarly to the parallel axes friction brake 50 and the parallel axes friction brake 80 previously described and may be positioned within the power actuator system 10 (e.g., as the parallel axes friction brake 40 shown in FIG. 5A or the friction brake 20 shown in FIG. 2) to provide similar drag torque characteristics. Additionally, the unidirectional parallel axes friction brake 110 may provide a one-way clutch function such that rotation in one direction engages the friction assembly 120 and rotation in the opposite direction bypasses the friction assembly.

[0035] When mated to a drive mechanism, such as the output screw 14 of the power actuator system 10, the connection is simple and only a plain cylinder on the lead screw / actuator drive shaft is required to connect to the one-way mechanism. These additional components make the drag brake one-way, resulting in near zero drag in one direction of rotation.

[0036] Other embodiments are possible, such as one-way clutches / bearings using balls, wrap springs, or sprags. These have the same functionality and can be combined with the various parallel axis friction brake embodiments described herein. Combination with one-way drag brakes is desirable for some actuators when additional drag is only needed in one direction, usually associated with gravity loads at the lid / gate. These direction dependent clutch functions can be added without significantly changing the overall footprint. These mechanisms can remain small because they only need to transmit a known and precise brake load.

[0037] 16-18 illustrate an anti-backdrive parallel shaft friction brake 140 according to one embodiment. In one embodiment, the anti-backdrive parallel shaft friction brake 140 includes a first brake housing portion 142a, a second brake housing portion 142b, an input spline 144, an output hub 162, a center gear 164, and a friction assembly 150. The friction assembly 150 includes a parallel shaft 146 and a ring clip 148. The center gear 164 includes teeth on its outer surface for engaging the friction assembly 150. The output hub 162 includes spline teeth on its inner surface and rollers 160. The input spline has external teeth 144a.

[0038] FIG 16 shows a perspective view of the anti-backdrive parallel shaft friction brake 140. The anti-backdrive parallel shaft friction brake 140 comprises a first brake housing portion 142a and a second brake housing portion 142b. FIG 17 shows an exploded view of the anti-backdrive parallel shaft friction brake 140, and FIG 18 shows a cross-sectional view substantially along the center of the anti-backdrive parallel shaft friction brake 140.

[0039] The anti-backdrive parallel shaft friction brake 140 operates very similarly to the parallel shaft friction brake 50 and the parallel shaft friction brake 80 previously described and may be positioned within the power actuator system 10 (e.g., as the parallel shaft friction brake 40 shown in FIG. 5A or the friction brake 20 shown in FIG. 2) to provide similar drag torque characteristics. Additionally, the anti-backdrive parallel shaft friction brake 140 provides an anti-backdrive clutch function whereby the friction assembly 150 is bypassed when a motor, e.g., motor 16, of the power actuator system 10 drives the external teeth 144a of the input spline 144 in either a clockwise or counterclockwise direction. Alternatively, the friction assembly 150 is engaged when the spline teeth on the inner surface of the output hub 162 are engaged by a clockwise or counterclockwise output load via the output screw 14.

[0040] There are other known methods for packaging roller backdrive prevention devices. There are other known backdrive prevention mechanisms (non-backdrive mechanisms or anti-backdrive mechanisms) that utilize wrap springs or other mechanisms that perform a similar function. The combination of the various embodiments of the parallel shaft friction brakes described herein with a backdrive prevention mechanism is a desirable configuration in some actuators when motor size and power consumption are important.

[0041] Although an automotive actuator has been used as a known example of an embodiment of the present invention, the present invention can be used in many other applications, for example where precise counter torque is required in a small package space, especially where stick-slip is a concern.

[0042] 19-21 illustrate a direct drive power actuator system 210 incorporating a parallel axis friction brake 220 according to one embodiment. As shown, the various embodiments of the parallel axis friction brake described herein may be used in a variety of drive systems, including spindle drive systems, as well as in direct drive systems and other applications.

[0043] In one embodiment, the direct drive power actuator system 210 includes an actuator housing 212, a motor 216, a first gearbox 218, a parallel shaft friction brake 220, a second gearbox 224, a bearing support 222, and a hinge drive 214. Rather than driving an output screw as in the spindle drive systems previously described, the direct drive power actuator system 210 utilizes the gear ratio between the first gearbox 218 and the second gearbox 224 to directly drive the hinge drive 214. The hinge drive 214 can be attached to a load, such as a gate or door, to open or close it.

[0044] The parallel axis friction brake 220 can be used similarly to the various embodiments of parallel axis friction brakes described herein to provide a precisely controlled drag force to the power actuator system 210. The parallel axis friction brake 220 includes a friction assembly 247 that includes an on-axis shaft parallel to the drive mechanism 245 to generate a drag torque, as previously described.

[0045] Although geared embodiments are shown herein, other applications of the various described embodiments of the parallel shaft friction brake are possible. Further options include the use of gear-like splines, which can facilitate integration with splined shafts for connection to a gear box, running through a belt or chain, or other mechanical connection. In these embodiments, a geared connection is shown in which the brake rotates faster than the central gear / drive shaft. Other speed ratios are possible and are within the scope of the present invention.

[0046] While specific embodiments have been shown and described herein, those skilled in the art will recognize that various alternative and / or equivalent implementations may be substituted for the specific embodiments shown and described herein without departing from the scope of the invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Accordingly, it is intended that the invention be limited only by the claims and the equivalents thereof.

Claims

1. An actuator housing; a rotatable drive shaft at least partially contained within the actuator housing; a parallel axis friction brake configured to engage the drive shaft and provide a resistance force to the rotatable drive shaft; Equipped with The parallel shaft friction brake is a brake housing coupled to the actuator housing; and a friction assembly, The friction assembly comprises: At least one parallel shaft parallel to the rotatable drive shaft; at least one clip pressed onto said at least one parallel shaft with an interference fit; having the friction assembly rotatably engages the drive shaft to generate the drag force and is coupled between the brake housing and the rotatable drive shaft; Actuator system.

2. The actuator system of claim 1 , wherein the friction assembly further comprises a lubricant.

3. a motor, the rotatable drive shaft being driven by the motor; An actuator system according to claim 1 or 2.

4. a rotatable drive shaft; a parallel axis friction brake configured to engage the drive shaft and provide a resistance force to the rotatable drive shaft; Equipped with The parallel axis friction brake further comprises a brake housing and a friction assembly. The friction assembly comprises: At least one parallel axis shaft; at least one clip pressed onto said at least one parallel-axis shaft with an interference fit; having the friction assembly engages the drive shaft and is coupled to the brake housing, such that at least a portion of the friction assembly rotates with the rotatable drive shaft to generate the drag force; Actuator system.

5. the actuator system is coupled to the vehicle such that the actuator system is disposed between a stationary first component and a moveable second component; the rotatable drive shaft is coupled to one of a lead screw spindle driven linear actuator and a direct drive rotary actuator; the lead screw spindle driven linear actuator and the direct drive rotary actuator are fixed to the moveable second component; the movable second component is moved by the lead screw spindle driven linear actuator or the direct drive rotary actuator; An actuator system according to any one of claims 1 to 4.

6. The parallel shaft friction brake further comprises a one-way device, The parallel shaft friction brake is Engaged upon rotation of the rotatable drive shaft in one direction and disengaged upon rotation of the rotatable drive shaft in the opposite direction. An actuator system according to any one of claims 1 to 5.

7. By further providing a motor and a clutch, the parallel shaft friction brake is disengaged when the motor is driving the rotatable drive shaft and is engaged when an output is engaged to a power actuator system; Or, the parallel shaft friction brake is engaged when the motor is driving the rotatable drive shaft and the parallel shaft friction brake is disengaged when an output is engaged to a power actuator system. An actuator system according to any one of claims 1 to 6.

8. the friction assembly further includes a portion having gear teeth having an outer diameter smaller than an outer diameter of the rotatable drive shaft; the gear teeth engage the rotatable drive shaft, and the friction assembly rotates faster than the rotatable drive shaft; An actuator system according to any one of claims 1 to 7.

9. A parallel axis friction brake coupled to a rotatable drive shaft, comprising: A brake housing; a friction assembly; Equipped with The friction assembly comprises: At least one parallel shaft parallel to the rotatable drive shaft; at least one clip pressed with an interference fit onto at least one of the parallel shafts or at least one sheet metal band wrapped around at least one of the parallel shafts; Equipped with The friction assembly engages the drive shaft and is coupled between the brake housing and the rotatable drive shaft. At least one of the at least one clip or the at least one sheet metal band and the at least one parallel shaft rotates with the rotation of the rotatable drive shaft to generate a drag force. Parallel shaft friction brake.

10. the rotatable drive shaft is coupled to one of a lead screw spindle driven linear actuator and a direct drive rotary actuator; the lead screw spindle driven linear actuator and the direct drive rotary actuator are fixed to a load to be moved by the lead screw spindle driven linear actuator or the direct drive rotary actuator; 10. A parallel axis friction brake as claimed in claim 9.

11. The parallel shaft friction brake further comprises a one-way device, The parallel shaft friction brake is Engaged upon rotation of the rotatable drive shaft in one direction and disengaged upon rotation of the rotatable drive shaft in the opposite direction.

11. A parallel shaft friction brake according to claim 9 or 10.

12. By further providing a motor and a clutch, the parallel shaft friction brake is disengaged when the motor is driving the rotatable drive shaft and is engaged when an output is engaged to a power actuator system; A parallel axis friction brake according to any one of claims 9 to 11.

13. the friction assembly further includes a portion having gear teeth having an outer diameter smaller than an outer diameter of the rotatable drive shaft; the gear teeth engage the rotatable drive shaft, and the friction assembly rotates faster than the rotatable drive shaft; A parallel shaft friction brake according to any one of claims 9 to 12.

14. The friction assembly is free of a separate spring or magnetic actuator. A parallel axis friction brake according to any one of claims 9 to 13.

15. The friction assembly further comprises a lubricant.

10. A parallel axis friction brake as claimed in claim 9.

16. a motor, the rotatable drive shaft being driven by the motor; 16. A parallel axis friction brake according to any one of claims 9 to 15.

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