CN1846037B - device for releasing the latch - Google Patents

Abstract

A power actuator for automotive door latches. The actuator includes an electric motor mounted in a housing. A worm is operatively coupled to the motor for driving rotation of the worm about an axis in a first rotational direction. A worm gear, which meshes with the worm, is mounted in the housing for rotation about an axis substantially orthogonal to the worm axis. A camshaft is mounted on the worm gear and has a rotation axis coincident with the gear axis. An output arm is affixed to the distal end of the camshaft for engaging the lever of a latch. The power actuator uses a reduced number ofcomponents.

Description

device for releasing the latch

technical field

The present invention generally relates to a device for releasing a latch, that is to say a powered actuator for a car latch, such as a powered actuator for releasing a trunk Powered actuator for movement between locked and unlocked positions.

Background technique

Cost is an important factor in the manufacture of automotive accessories such as electric latch releases. The number of components making up the powered actuator has an impact on product cost. Thus, known powered actuators for automotive closing latches have more components and therefore have a higher cost than the present invention.

Contents of the invention

A powered actuator for a latch of an automotive closure according to a preferred embodiment of the present invention has a lower number of parts than similar devices currently on the market.

According to one embodiment of the present invention, there is provided a powered actuator comprising: a housing; an electric motor mounted within said housing; an electric motor operatively coupled to said motor a worm, said motor for driving said worm to rotate about an axis in a first rotational direction; a worm gear engaged with said worm, mounted in a housing for rotation about an axis substantially perpendicular to said worm axis; a cam a shaft mounted on the worm gear and having an axis of rotation coincident with the axis of the worm gear, the camshaft having a distal end; and an output arm secured to the camshaft distal end.

The powered actuator can be used as a latch release. According to this embodiment, said latch release device comprises: a housing; an electric motor mounted within said housing; a worm operatively coupled to said motor, said motor for driving said worm rotates about an axis in a first direction of rotation; a worm gear engaged with the worm, mounted within the housing for rotation about an axis substantially perpendicular to the axis of the worm; a camshaft, mounted on the worm, and having a the coincident axis of rotation of the axis of the worm gear, the camshaft having a distal end extending outside the housing; and a cam fixed at the outer end of the camshaft, the surface of which is adapted to engage the latch for use when the motor drives Next, the latch is moved from the closed position to the released position as the worm wheel rotates in the first direction from the first position to the second position.

In a preferred embodiment of the release device, the worm has a small diameter which facilitates the overall dimensions of the device. The combination of the output cam and the worm gear reduction system also results in a high overall output force.

In a preferred embodiment of the latch release, the worm wheel is biased against rotation from the first position to the second position. Providing a biased return spring provides repeatable unidirectional force output, while the absence of such a spring provides bidirectional torque/force output.

In a specific embodiment, the device includes conductive contacts embedded in the housing as the housing is molded from plastic resin to make electrical contact with the motor while extending to the outside of the housing, to connect to the power supply. The integration of electrical connections is another example of further functionality achieved without additional components or complexity by means of the invention described herein.

The housing of the latch release may comprise an injection molded closure plate, wherein the hollow portion of the housing and the plate have opposing walls configured to hold the hollow portion and the plate in together adjoining the housing of the motor, and the plate further includes a protrusion extending into the interior of the housing to abut a side of the motor housing for preventing the motor from moving back and forth.

In another preferred aspect, the closure plate and said housing include a plurality of mutually communicating holes arranged to allow simultaneous fastening of the housing and closure plate together and said means adjacent to said latch. and cams operatively adjacent to these devices are fastened. This technical solution allows the use of the same fasteners to mount the unit to the main latch or mechanism and to join together the housing parts of the device. The preferred embodiment thus provides a versatile, customizable, compact, low cost mechanism for power release or locking.

Description of drawings

Embodiments of the present invention are described in detail below with reference to the accompanying drawings, in which:

Figure 1a is a perspective view of the motorized latch release device of the present invention mounted on a motor vehicle and in a closed position;

Fig. 1b is similar to Fig. 1a, wherein the electric latch release is in an open position;

Figure 2 is a partially exploded view, taken from a similar vantage point as the previous figures, with the latch release cover removed and partially exploded to show the mechanism's electric motor and worm gear structure;

Figure 3 is a more fully exploded view taken from a similar vantage point as the previous figures to show the inner housing, worm wheel and spring for biasing said worm wheel towards the closed position, and the placement area for the motor;

Figure 4 is a plan view of the housing, spring and worm wheel with the worm wheel in the closed position, wherein the worm wheel is in the closed position;

FIG. 5 is similar to FIG. 4 but with the worm wheel fully rotated to the open position shown in FIG. 1 .

Figure 6 is a perspective view of the exterior of the housing on the side opposite to that shown in Figure 1;

Figure 7 is a perspective view from a similar vantage point as Figure 6, partially exploded to show the motor and cover;

Figure 8 is a top view of the device when oriented as in Figure 1;

Figure 9 is a bottom view of the device when oriented as in Figure 1;

Figure 10 is a front view of the right end of the device when oriented as shown in Figure 1;

Figure 11 is a left end elevational view of the device when oriented as in Figure 1;

Figure 12 is a rear elevational view of the device when oriented as in Figure 1;

Fig. 13 is a plan view of the worm wheel observed from the left side of Fig. 7;

Figure 14 is a cross-sectional view of the worm wheel showing the cam mounted with the worm wheel.

Detailed ways

Referring to the drawings, an electric latch release device 20 of the present invention is generally shown in FIGS. 1a and 1b. In the figure, the device is shown mounted on a motor vehicle to allow the driver to release the remotely controlled trunk. As shown in Figure 1a, the luggage case is in the closed and locked position. The latch 22 - part of a conventional luggage lock mechanism - is biased in a clockwise direction. In general, the device 20 operates by rotation of the output cam 28 from the closed position shown in FIG. 1 a to the open position shown in FIG. 1 b. This clockwise rotation (as seen in Figures 1a and 1b) forces the latch 22 to move rightward from its closed position to the released position shown in Figure 1b where the latch is. The output cam 28 automatically turns back to the closed position of FIG. 1a after reaching the fully open position. The device 20 and its operation are described in detail below.

As shown in FIGS. 2 and 3 , the device comprises a hollow shell 30 and a closure plate 32 . These components are injection molded as individual plastic components in a single-step process. A socket, described further below, is integrally molded as part of the housing and secured within the plastic member for connecting the electric motor 34 of the device to an external power source. The housing and closure plate are made of a suitable plastic, in this example glass and mineral reinforced nylon resin. Polymers are typically chosen for high strength and stiffness, dimensional stability, and high temperature resistance.

As seen in FIGS. 2 and 3 , the electric motor 34 includes an output shaft 36 that drives a worm 38 mounted to the outer end of the shaft. The device comprises a worm wheel 40 meshing with the worm, a helical spring 42, and a camshaft 44 on which the output cam 28 is mounted. As described in detail below, these components are arranged such that the spring biases the worm wheel, which in turn biases the output cam in a counterclockwise direction (as viewed in FIGS. 1 and 3 ) towards the closed position. The motor runs, and the worm wheel is driven to rotate clockwise through the worm, that is, to rotate toward the open position shown in FIG. 1b.

The electric motor 34 is a high output torque, low backlash torque 200 series motor with integrated thermal protection, EMC protection and a knurled shaft. Such motors are commercially available, for example, from Mabuchi Motor Co., Ltd or Johnson Electric North American, Inc. The motor is mounted in a fixed position within the housing and is held in place by positive abutment against the surfaces of the housing and closure plate. The cylindrical foot 48 of the motor is mounted on the concave surface 46 of the housing. The motor housing directly adjoins the first and second surfaces 50 , 52 . On the inner side of the closing plate 32 are two rows of triangular projections 54 whose end faces 56 are arranged and oriented so as to abut the housing of the motor together with the inner surface area 58 of the plate. The cylindrical foot 60 is received between the upstanding members 62, 64 of the inner housing of the device, the side surfaces of each member abutting to help hold the shaft end of the motor in the orientation as in FIG. 1 without moving side to side. . The motor includes first and second openings 66, 68 in which electrical terminals are disposed. Terminal posts 70, 72 are molded into the housing and are received within openings 66, 68 of the motor, each terminal post being in electrical contact with a terminal of the motor.

The housing includes a receptacle 74 having first and second prongs 75a, 75b which are externally molded into the rear of the housing (oriented as in FIG. 1 ) a part of. The pins are each electrically connected to the posts 70, 72 by an embedded wire. Preferably, the socket and prongs are designed to receive a standard plug for powering the motor of the latch release. However, any suitable form of electrical connection will suffice.

Turning back to the drive mechanism of the device, the drive end of the shaft 36 extends approximately 1.5 cm beyond the end of the cylinder 60 on which the shaft 36 is suitably mounted. The free end of the shaft has knurled ridges (not shown) parallel to the longitudinal axis of the shaft, which are pressed into the shaft for approximately 7mm length. The worm 38 is tubular with an inner diameter slightly smaller than the outer diameter of the shaft 36 so that the accommodation of the worm on the shaft results in a sufficiently tight snug fit for the expected life of the device. During assembly of the worm onto the shaft, the ridges on the shaft are deformed slightly radially inwards, and the ridges help to ensure that the worm is rigidly fixed to the shaft so that during operation of the device does not rotate relative to the shaft.

The worm gear 40 is preferably injection molded in a single step from homopolymer acetal, chosen for its low coefficient of friction, high wear resistance, and dimensional stability. Other materials can also be used instead. The worm gear is molded to include a tubular mounting shaft 80 (see Figure 7). The shaft 80 is received into the open end of a cylindrical mount 82 integrally molded into the housing 30 . The outer diameter of the shaft 80 is about 1 cm. The outer diameter of the shaft 80 and the inner diameter of the cylindrical mount 82 are close in size to each other so that there is only little play between the two components, but at the same time the worm wheel is free to rotate relative to the cylindrical mount 82 . The abutment surface is very smooth and has a circular cross-section and presents minimal frictional resistance to rotation of the worm gear about the central axis of the shaft.

In the illustrated embodiment, the outer diameter of the worm wheel 40 is approximately 2.7 cm, while the width of the rim, ie the tooth contact portion of the wheel, is approximately 1.1 cm, and the overall height of the hub 80 is approximately 1.6 cm. A stop 84 is molded as part of the worm wheel. The stop 84 protrudes approximately 4 mm from the toothed rim and extends approximately 45 degrees around the circumference of the rim. Where a full 360 degrees of output rotation is desired, this stop 84 may be omitted. The stop 86 molded as part of the housing is radially spaced from the mount 82 by a slightly smaller distance than the radial distance between the worm wheel stop 84 and the center of the shaft 80 . The housing stop 86, together with the wheel stop 84, adjusts the rotational (angular) distance allowing the worm wheel to move between a closed position (FIG. 1a) and an open position (FIG. 1b) over a rotational distance of approximately 270°. The arc length of housing stop 86 is about 45°, and the arc length of worm gear stop 84 is about 45°, so that the two stops total extended by approximately 90°. When the worm wheel 40 is properly installed and in the closed position, the abutment surface 90 of the wheel stop and the abutment surface 92 of the housing stop abut each other to prevent clockwise rotation of the worm wheel. When the worm wheel is turned counterclockwise to the extreme open position (see FIG. 1b ), the abutment surfaces 94, 96 of the worm wheel stop and housing stop respectively abut each other to prevent further counterclockwise movement of the worm wheel. Since the combined distance of the two stops on a common circumference is 90°, the rotation of the worm wheel between the closed position and the open position amounts to 270°. As will be further understood from below, this is the rotational (angular) distance traveled by the cam 28 during operation of the device to release the latch.

The worm gear 40 is biased towards the closed position by a coil spring 42 . The spring 42 is mounted within a generally annular space provided between the inner surface 98 of the rim, the outer surface of the worm shaft 80 and the inner surface 100 of the worm wall 102 . Located within the annulus is a protrusion 104 that protrudes from the wall of the worm wheel and acts as a detent for a spring hooked end 106 . The protrusion 104 includes an overhang 108 . The overhangs 108 help to mount the spring during assembly of the device by resisting axial movement of the spring hook (eg, in a direction parallel to the center axis of the wheel and away from the inner wall 102) and facilitate It is ensured that the hook portion 106 of the spring does not slip out of the detent during operation of the device. The spring end 110 is hooked to snap over the housing surface 96 . It should be noted at this point that the worm gear stop 84 is generally spaced generally radially outward from the spring 42, but that the hook 110 projects radially outward from the rest of the spring to catch over the surface 96 which Radially disposed to abut surface 94 of the worm gear stop. Clearance is provided for the stop 84 to travel past the hook 110 when the worm wheel is rotated to the closed position by placing the hook in the recess 112, as shown in FIG. The perimeter of the stop 86 extends radially outward. The hook 110 is thus axially spaced (towards the bottom of the housing) from the stop 84 to allow the stop 84 to pass through the hook 110 .

Spring 42 is mounted in constant tension and is preferably made of spring wire and stainless steel. This results in a constant biasing force on the worm wheel towards the closed position, ie in the clockwise direction in the example Figures 1a and 1b. As the worm wheel turns under the force provided by the motor through the worm (as described in more detail below), the tension on the spring increases.

The motive power of the motor 34 is transmitted to the worm wheel 40 through the worm 38 . The threads 76 of the worm engage the teeth 114, and the axial pitch and pitch of the teeth 114 are designed to mesh with the axial pitch and pitch of the threads of the worm. Actuation of the motor 34 thus causes the worm 38 to rotate clockwise (as viewed from the left in Figure 1a), which in turn causes the worm wheel 40 to rotate in a counterclockwise direction - as viewed in Figure 1a. Actuation of the motor 34 by applying the appropriate current can be accomplished by an operator operating a suitably wired button, or by actuating an electrical circuit under remote control or the like. In the position of Figure 4, the torque exerted by the spring on the worm wheel is about 330Nmm, while when the worm wheel is in the position shown in Figure 5, the torque from the spring is about 380Nmm.

As previously described, rotation of the worm wheel 40 will eventually be stopped by the abutment of the stop surfaces 94, 96 as the worm wheel rotates through an angle of approximately 270° to the fully open position. The worm gear stalls, preventing the worm from turning, thus stalling the motor 34 . Power to the motor supply is cut off and the energy stored in the coil spring causes the worm gear to rotate back to the closed position.

The worm gear 40 has a central bore 116 that accommodates a shaft 44 that is mounted to the cam 28 . The cam and shaft are injection molded as a single component made of the same plastic as the worm gear. The outer profile of the cross-section of the shaft 44 matches the cross-section of the central bore 116 of the worm wheel, and said cross-section is non-circular. The shaft 44 received in said bore is thus fixed against rotation relative to the axis of the worm wheel. The mounted shaft 44 is also centered on the central axis of the worm wheel so that as the worm wheel rotates about the axis, the cam shaft also rotates about this axis. It is further noted that the engagement between the shaft 44 and the surface of the bore serves to orient the cam to operate between closed and open positions.

As described further below, the cam 28 is installed as part of the device after the closure plate and housing are assembled. This is accomplished by tabs 150 on the free end of the shaft 44 . Each tab is located at one end of a finger 152 that is radially spaced from each other on opposite sides of the central axis of the shaft 44 . Each tab includes an abutment surface 154 that opposes and abuts a surface 156 surrounding the central bore of the worm wheel 40 . Opposite the tab surface 154 is a surface 158 of the shaft 44 which adjoins the surface 160 of the worm wheel. Thus, for installation, camshaft 44 passes through bore 162 and is inserted into worm wheel bore 116 . The chamfered front surface 164 of the tab abuts against the inner surface of the narrower portion 117 of the bore 116, the tab compressing the resilient fingers together when passing through the inner surface of the narrower portion 117 of the narrow passage. , the resilient fingers eventually spring back to the installed position shown in FIG. 14 where surfaces 154, 156 abut each other and surfaces 158, 160 abut each other to secure the cam against axial movement.

The cross-sectional profile of the cam surface is airfoil-shaped. Rotation of the camshaft 44 moves the latch 22 from the closed position to the released position through the cam surface, as shown in FIGS. 1a and 1b. As the shaft 44 rotates, a cam surface area generally indicated at 118 contacts the latch 22 . As this rotation occurs, the radial distance (from the center of the shaft) of the contact portion of the cam surface that is in contact with the latch increases, causing a forced movement of the latch from the closed position towards the released position. As mentioned above, the worm wheel and fixed cam rotate until the fully open position 28a (Fig. 1b) is reached and the motor 34 stalls which causes the cam to eventually return to the closed position.

The cam profile converts the output torque into a linear force that pushes against movable rods, plates, and other parts to which one wishes to apply force. This cam acts as a further worm gear ratio for the system, where the smaller distance pushed by a full rotation of the cam is interpreted as the greater force exerted by the cam.

Since the installed device may occasionally be exposed to a small amount of water when the trunk is opened during a heavy rain or the like. To reduce the likelihood of damage from these exposures, channels for the flow of these liquids are provided around the perimeter of the closed edge of the plate. Ridges 120 molded as part of housing 30 and ridges 122 molded as part of closure panel 32 are thus shaped to abut opposing surfaces (of the closure panel and housing respectively) to provide a limited seal against water ingress. In addition, the ridges are spaced slightly inward from the extreme perimeter, thereby forming a fluid flow channel 124 around the perimeter of the ridges.

During manufacture of the device 20 , the housing 30 and closure plate 32 are conveniently assembled together by a single assembly screw 126 passing through the plate hole 128 with the screw shank received in the housing hole 130 . The cross-section of the hole 130 is smaller than that of the screw shank so that the thread of the screw is embedded in the plastic wall of the housing during assembly.

The housing and plate have three further pairs of communicating holes 132 , 134 , 136 . These holes are used during mounting of the device to the automatic latch via fasteners 138 , 140 , 142 . When installed, the areas 144, 146, 148 on the surface of the outer panel surrounding these holes are in positive abutting contact with the surface of the vehicle. (The same can be done for the outer area of the housing surrounding the hole.) In this way, when the device is mounted with the rest of the latch, the fasteners 138, 140, 142 are clamped by the housing and closure. Between the head of the head and the surface of the vehicle, pressure is further exerted on the shell and closure plates, and the plate areas 144, 146, 148 of the shell and closure are in abutting contact with the surface of the vehicle.

The spring 42 of the arrangement shown can be omitted, which of course removes the biasing force from the worm wheel. In this case, the control circuitry of the device can be altered to drive the motor in a first direction and a second direction, thereby moving the cam from the first position shown in Figures 1a and 1b to the second position ( Nominally moving from the open position to the closed position), and moving the cam from the second position to the first position. The means are thus optionally for example adapted to move the latch between a first and a second position, eg the locking bar is movable between a locked and an unlocked position. It will be appreciated that the cam or other output arm may have different profiles for different purposes.

The illustrated embodiments have been described in detail for purposes of illustration. Those of ordinary skill in the art will appreciate that various modifications may be made to the embodiments described herein without departing from the spirit of the invention.

Claims (11)

1. A device for releasing a latch comprising: case; an electric motor mounted within said housing; a worm operatively coupled to the motor for driving the worm about an axis in a first direction of rotation; a worm gear engaged with the worm, mounted within the housing for rotation about an axis generally perpendicular to the axis of the worm; a camshaft mounted on the worm wheel and having an axis of rotation coincident with the worm wheel axis, the distal end of the camshaft extending to the outside of the housing; a cam affixed to the outer end of the camshaft, the surface of which is adapted to engage the latch for movement under the control of the motor as the worm wheel is rotated in a first direction from a first position to a second position moving the latch from a closed position to a released position; and wherein The worm wheel is biased against rotation from the first position to the second position by a spring; the spring is connected between the worm wheel and the housing so that as the worm wheel is controlled by the motor from The first position is rotated to the second position, energy is transferred from the motor to the spring, and when the motor is de-energized, the stored energy in the spring causes the worm wheel to move in the opposite direction from the first rotate in a second direction from the second position to the first position; and The housing includes a first stopper and a second stopper, and the worm wheel includes a first stopper and a second stopper, wherein when the worm wheel is in the first position, the The first stopper of the housing and the first stopper of the worm wheel abut against each other to prevent the rotation of the worm wheel in the second direction, and when the worm wheel is in the second position, the second stopper of the housing The moving member and the second stopper of the worm wheel abut against each other to prevent the worm wheel from rotating in the first direction. 2. The apparatus of claim 1, wherein said worm gear includes a shaft rotatably mounted to said housing, and an outer rim spaced from said shaft, said outer rim bearing against said housing. The teeth that engage the worm, and the spring is a helical spring located in a generally annular space between the shaft and the inner surface of the rim. 3. The apparatus of claim 1, wherein said housing includes an injection molded tubular mount extending into the interior of said housing, and said worm gear is rotatably mounted on the injection molded tubular mount. 4. The device of claim 3, wherein the first and second stops of the housing are integrally molded with the housing. 5. The device of claim 4, wherein said device further comprises an injection molded closure plate, said housing comprises a hollow portion, said housing and said plate have opposing walls, and said opposing the wall is configured to abut the housing of the motor when the hollow portion and the plate are secured together, and the plate further includes a protrusion extending into the interior of the housing to abut a side of the motor housing, Used to stop the motor from moving back and forth. 6. The device of claim 5, wherein the hollow portion includes an upstanding peripheral ridge integrally molded with the housing, the upstanding peripheral ridge being configured to abut the inner surface of the plate, and the housing The plate of the body includes an upstanding peripheral ridge integrally molded therewith configured to adjoin the inner surface of the housing to prevent water from flowing into the interior of the housing, and wherein the ridge is disposed about its The periphery provides a water flow channel. 7. Apparatus as claimed in claim 6, wherein said tubular mount of said housing has an open end, said worm wheel being rotatably mounted on said open end by means of a shaft protruding from and received in said open end. In the open end, the worm wheel includes a rim spaced from the shaft, and the spring is located between the rim and a tubular mount of the housing. 8. The apparatus of claim 7, wherein said housing plate includes a bore communicating with the central bore of said worm wheel to allow said camshaft to pass therethrough, and wherein the distal end of said camshaft includes at least one resilient finger passing through the communicating hole and having a surface in abutting contact with an opposing surface of the worm wheel to prevent axial movement of the camshaft from the worm wheel bore pull out. 9. The apparatus of claim 8, wherein said cam surface for engaging said latch is oriented to move said latch in one direction as said worm wheel is rotated in said first direction, And this direction has a vector portion that is not parallel to the direction of rotation of the worm gear shaft. 10. The apparatus of claim 5, further comprising a conductive contact embedded within the housing as the housing is molded, the conductive contact making electrical contact with the motor and extending to the the outside of the case to connect to the power supply. 11. The device of claim 5, wherein the housing and closure plate include a plurality of holes in communication with each other, the holes being arranged to allow simultaneous fastening of the housing and closure plate together and Said means of said latch is fastened with a cam operatively adjacent thereto.

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