Foldable rear view mirror assembly for a vehicle

A foldable rearview mirror assembly for a vehicle is disclosed. The assembly comprises: a mounting bracket mountable to a vehicle, the mounting bracket having a base with detent features disposed on a detent circle on the base; a mirror head frame rotatably mounted to the mirror base for rotation about a mirror head axis, the frame having detent features to match the detent features of the base, the detent features of the base and the frame forming a detent system, the detent system having at least a drive position. The frame is shaped to provide an aperture to receive either of: a manual fold insert; or a power fold mechanism having a clutch mechanism, the aperture at least partially inboard in a radial direction with respect to the detent features on the frame whereby at least the clutch mechanism of the power fold mechanism can be accommodated to operate on a smaller radius than that of the detent features.

FIELD OF INVENTION

The invention is based on a priority patent application AU2009201083 which is hereby incorporated by reference.

The present invention relates to fold mechanisms for external rear vision systems of motor vehicles, and in particular to fold mechanisms that incorporate or at least provide for, power folding.

BACKGROUND OF THE INVENTION

Motor vehicles typically have two external rear vision mirror assemblies. The mirror assemblies typically have a mirror head that is designed to rotate about a substantially vertical pivot axis in both forward and rearward directions. The mirror head is typically held in its driving position by a detent which allows manual movement of the mirror head to a parked position and manual movement to a forward position. There are a number of reasons for this. One reason is safety. By having a mirror that can “break away” to move from a deployed position to a parked or forward position, injury to people can be avoided or at least minimised which is a mandatory feature for a approvals. Furthermore, damage to the mirror head can be avoided or at least minimised by allowing it to move when it hits obstructions. It is also useful to have a mirror head that can be parked, that is rotated to a position substantially parallel to the side of the vehicle, so as to narrow the effective width of the vehicle. This is particularly useful when the vehicle is parked in or is travelling along narrow or congested roadways. It is also useful for loading vehicles onto trucks for transport to be able to park the mirror heads.

Modern external rear vision mirrors, in addition to having a detent mechanism to hold the mirror head in a deployed position while at the same time enabling forward folding and rearward folding of the mirror head, also have electric drive systems to allow the operator to drive the head at least to its parked position. Some external rear view mirror assemblies have more sophisticated electric systems that allow the operator to redeploy the mirror head to a drive position after it has been manually pushed forward or rearward. These mirror systems are typically referred to as power fold mirrors.

Power fold mirrors typically employ power fold mechanisms that hold the mirror head against rotation in one direction with respect to the mirror base. This is usually achieved using a non-back-drivable gear train (such as a gear train employing a worm gear). As a result, the gear train is subject to significant forces and or torques resulting from wind, road and static forces. Thus, the power fold mechanism must be strong, rigid and have a good fastening system to both the mirror base and to the mirror frame. These requirements increase complexity and cost. They also mean that the mirror assembly must be specifically designed as a power fold mirror assembly with many different components to a non-power fold system.

A problem with some power fold mechanisms is that when the mirror head is manually rotated away from its drive or deployed position, torque is transmitted through the path of drive train before a clutch disengages. This is a problem for a number of reasons, one of which is as follows. The clutch for the drive train is sometimes radially inboard of the manual fold detent system. This means that even during normal operation, vibration loads can be transmitted through the drive train system and hence through the radially inboard detents. Because the radially inboard detents are not as far radially outboard as the manual fold detents, this results in less stability and increased vibration of the mirror head compared to that achieved with non-power folding mirrors that only have a manual fold detent system operating on a larger radius.

An external rear view mirror for automobiles is disclosed in U.S. Pat. No. 6,022,113 The rear view mirror disclosed by that US patent has a non-back-drivable worm gear that locks a gear wheel in place. The gear wheel can be driven by the worm gear but cannot drive back through the worm gear. Thus, the gear wheel can be used (and is used) as a stop, holding the drive housing4and hence the mirror head against fold path limiter stop cams on the mirror base2. As a result, the gear train is subject to significant forces resulting from wind, road and static forces while it is held in the drive position. These forces are transmitted from the mirror head3to the powerfold housing4via a case frame in the mirror head. The force is then further transferred through the worm and gear teeth to the detent system on the bottom of the gear. Here it meets the reaction force provided by the spring that clamps the system. If the force supplied is great enough, the detent system will disengage compressing the spring and allowing the mirror head to manually rotate it to the parked position.

As should be apparent from the above, with the mirror described in U.S. Pat. No. 6,022,113, the powerfold housing4, the drive train including gear wheel6and worm gear11are subject to significant forces and must be strong and rigid. Furthermore, the mirror of U.S. Pat. No. 6,022,113 cannot really be modified to become a non-powerfold mirror assembly.

Existing power fold rear view mirrors are designed separately from the design of simple pivotal mirrors. Therefore the supply of a vehicle platform with rear vie mirrors requests different designs for the two different types of mirror which increases the over all costs. The idea of the invention is to overcome the problem of two different designs and to use a common design for mirro bracket and mirror housing with or without powerfold actuation.

It is an object of the present invention to provide an improved power fold mechanism that overcomes at least some of the problems outlined above or at least offers a useful choice to reduce costs for different designs of mirror components.

SUMMARY OF THE INVENTION

The invention is an external rear view mirror assembly to be fitted to a motor vehicle, the assembly comprising:a mounting bracket mountable to a vehicle, the mounting bracket having a base;a mirror head frame rotatably mounted to the base for rotation about a mirror head axis;a detent operably interposed between the base and the frame, the detent having at least a drive position;a primary spring acting between the frame and the base in a direction parallel to the mirror head axis, the primary spring for holding the detent engaged in the detent position(s); anda power fold mechanism operably interposed between the mirror base and the frame, the power fold mechanism having a drive train, and a clutch mechanism, the clutch mechanism comprising a pair of opposed clutching faces connecting the drive train to the base when the drive train is driving, the clutch mechanism arranged and constructed such that forces are not transmitted from the mirror head frame to the drive train during manual folding of the mirror head when the drive train is not driving.

Referring toFIG. 1, a foldable rear view mirror assembly for a vehicle is shown. The mirror assembly has a mounting bracket20mountable to a vehicle (not shown). The mounting bracket20has a base21with detent features24disposed on a detent circle on the base21. A mirror head51having a mirror head frame50is rotatably mounted to the base21for rotation about a mirror head axis53. The frame50has detent features57to match the detent features24of the base. The detent features24and57at the base21and the frame50form a detent system. The detent system has at least a drive position, the position shown inFIG. 1. The drive position is the position that is usually adopted when the vehicle is in operation so that the vehicle driver can use the actual mirror within the mirror mount39to obtain rear vision.

Now turning toFIGS. 2 and 3, it can be seen that the frame50is shaped to provide an aperture59for receiving either of the power fold mechanism60shown inFIG. 2or a manual fold insert (comprised of a spring58′ and a spigot29′) as shown inFIG. 3. This means that the design of mirror head frame50and mirror base is identical for both features with or without power fold.

The aperture59is at least partially inboard in a radial direction with respect to the detent57on the frame50whereby at least a clutch mechanism of the power fold mechanism60can be accommodated to operate on a smaller radius (measured from the mirror head axis53shown inFIG. 1) than that of the detent features57. This is important for the manual fold steps are made on detent levels and the larger radius of the position of detents help to fix the mirror head rigidly. The reduction of the power fold60and the implemented clutch mechanism in the inner radius of the aperture is on the one side a way to implement a common design for power fold and none power fold use and the reduce mechanical forces to the clutch.

The power fold mechanism60has a spigot29, a housing40, a spring58, a drive train70(best shown inFIG. 6) and a clutch mechanism. The spigot29holds the spring58compressed between the base21and the housing40and hence the frame50, thereby holding the detent formed by detent features24and57engaged against at least wind loads. The clutch mechanism comprises a pair of opposed clutching faces (which will be described later) biased together by the spring58. The clutching faces connect the drive train70to the base21when the drive train is driving.

With the foldable rear view mirror assembly described above and shown inFIGS. 1-3, a manual fold insert as illustrated inFIG. 3can be provided instead of the power fold mechanism60. The manual fold insert simply comprises a spigot29′ and a spring58′. The spigot29′ holds the spring58′ compressed between the base21and the frame50thereby holding the detent formed by detent feature57on the frame50and detent features24on the base21engaged against at least wind loads.

The power fold mechanism will now be described with reference to diagrammaticFIG. 9a.FIG. 9ashows diagrammatically a base21(that typically forms part of a mirror bracket directly mountable to a vehicle), and a mirror head frame50rotatably mounted to the base21for rotation about a mirror head axis53.

A detent that is operably interposed between the base21and the frame50is formed by detent features24and57located on the mirror base21and frame50respectively. The detent has a drive position, the position shown in diagrammaticFIG. 9aandFIG. 1.

A primary spring58acts between the frame50and the base21by virtue of its compression between a retainer30connected to a spigot29which fits by a bayonet fitting at its lower end into the base21. The primary spring58acts in a direction parallel to the mirror head axis53and holds the detent engaged in the detent position.

Referring now to the exploded view ofFIG. 6as well as diagrammaticFIG. 9a, the powerfold mechanism will now be described in more detail. The power fold mechanism is operably interposed between the mirror base21and frame50and comprises a housing40installable into the mirror head frame50for rotation therewith. The power fold mechanism also comprises a drive train70that includes a motor75mounted to the housing. The drive train includes a worm gear72that engages a drive gear78that has a plurality of circumferentially spaced apart axially extending protrusions79.

The power fold mechanism also includes a main ramp ring100interposed between the drive gear78and the base21. The main ramp ring100has a plurality of ramp recesses103for receiving respective protrusions79of the drive gear78such that relative rotation between the drive gear78and the main ramp ring100results in their relative axial displacement. The main ramp ring100is operatively connected to the base so as to provide a clutch. The clutch has an engaged position where the main ramp ring100is rotationally fixed with respect to the base21and a disengaged position in which the main ramp ring100is rotatable with respect to the base21about axis53.

Referring now toFIG. 6, it can be seen that a drive disc90connects into the base21. The drive disc90has a clutch face94comprising clutch ramps95arranged to engage with a corresponding clutching face and clutching ramps107and109on the underside of the main ramp ring100(shown inFIG. 9,FIG. 9aandFIG. 8c).

A manual fold torque transmission member in the form of a manual fold ring is splined to the housing40to allow relative axial movement but not relative rotational movement with respect to the housing40. The manual fold ring has an engaged position in which it engages the main ramp ring100such that the main ramp ring100rotates with the housing40. The manual fold ring120also has a disengaged position in which the main ramp ring100is not constrained to rotate with the housing40. This arrangement, which will become clearer when the operation of the mirror head is described below, ensures that during manual folding of the mirror head from the drive position (for instance to the park position) forces are not transmitted from the mirror head frame50to the drive gear78.

An electric stall ring110is provided to stop the drive gear78at the drive position during electric folding from the park position to the drive position. This reduces delay in the operation of the mechanism. The electric stall ring110also positions the drive gear78to prevent it engaging the main ramp ring100during manual folding and thus prevents load being transferred to the drive gear78during the folding. The electric stall ring110is splined to the housing40by way of a spline key that sits in the spline key way49as shown inFIGS. 8aand8b.

The electric stall ring110solves a problem that occurs with some powerfold mechanisms. It prevents the powerfold mechanism driving “through the clutch”. That is it stops the powerfold mechanism overcoming the holding torque of the clutch. This is because the electric stall ring produces a force loop with the worm gear72pushing on the housing40, the gears72pushing on the drive gear78, the drive gear78pushing on the electric stall ring110and the electric stall ring110pushing back onto the housing40(the electric stall ring110is splined to the housing40). Thus the stall torque that is generated once the stall position is reached is confined to the drive train and the housing and does not transfer to the clutch. This means that the designer can design the system to use a higher drive torque, even a drive torque higher than the clutch torque. In practice, and with the embodiment of the invention shown in the drawings, the drive torque is less than the clutch torque. With the embodiment shown, employing the electric stall ring110, even if the system wears, the powerfold system will not drive “through the clutch”. The system employing electric stall ring110also has the advantage that the clutch system is not stressed as frequently as would otherwise be the case.

A secondary ramp ring220is interposed between the primary spring58and the drive gear78. The secondary ramp ring transfers spring force from the spring58to the drive gear78. The helper ramps224of the secondary ramp ring220reduce the torque required to overcome the detents during electric operation. The reaction faces222of the secondary ramp ring transmit drive train reaction torque to the base for electric fold out (the secondary ramp ring220is splined to the spigot29by virtue of spline keys229most clearly shown inFIG. 7.

Referring now toFIG. 6, it can be seen that there are a number of springs aside from the primary spring58. These springs include an electric stall spring111that biases the electric stall ring110upwards and into engagement with the drive gear78. A manual fold spring130is provided to bias the manual fold ring120upwards and into engagement with the main ramp ring100(to the position shown inFIG. 9a). This spring is shown inFIG. 8a. The spring130includes projections131that act to restrain movement of the electric stall ring110(this is shown diagrammatically inFIG. 9afor instance). The manual fold spring130includes a fold132. It is this fold132that biases the manual fold ring120upwards into engagement with the main ramp ring100. A main ramp ring spring101is also provided to bias the main ramp ring100downwards.

Operation of the foldable rear view mirror assembly will now be described with reference to the diagrammatic figures.

Operation of Manual Version

Referring toFIG. 3andFIGS. 5ato5c, manual folding of the mirror head and hence frame50with respect to the mirror bracket and hence base21can be seen. As the mirror head and hence mirror frame50is rotated with respect to the mirror base21, the detent features57on the frame50ride up the detent features24on the mirror base as is shown progressively fromFIGS. 5ato5b. As this happens, the spring58′ is compressed.FIG. 5cshows the frame park stop54reaching and stopping at the base rearward fold (park) end stop28.

Operation of Powerfold Version

Manual Fold in from Drive to Park Position

Operation of the external rear view mirror assembly fitted with a power fold mechanism60will now be described. Referring toFIGS. 1,2and diagrammaticFIGS. 11ato11e, commencement of manual folding from the drive position to the park position is shown. In the transition from the position shown inFIG. 11ato the position shown inFIG. 11b, it can be seen that the frame50rides up the detents57and24and the clearance between the manual fold ring pushing face122and the main ramp ring push face102are taken up so that torque is transmitted from the frame50to the housing40to the manual fold ring120to the detent features24and57such that forces are not transmitted to the drive gear78. This is shown diagrammatically inFIG. 9aby the fact that clearance is maintained between the protrusions79of the drive gear78within the recesses103within the main ramp ring100.

InFIG. 11c, it can be seen that the main ramp ring100has moved up inside the power fold mechanism without contacting the gear drive78or its protrusions79. Furthermore, it can be seen that the electric stall ring110has disengaged from the drive gear78for subsequent electric function.

InFIG. 11d, it can be seen that the frame50continues to rotate towards the park position and, finally, inFIG. 11e, the frame50reaches the park position when the end stop28is contacted.

Electric Fold Out from the Park to Drive Position

Referring now toFIGS. 12ato12e, electric fold out from the park position to the drive (or deployed) position will now be described. Referring first toFIG. 12a, power is applied to the motor75which results in torque at the worm gear72. Worm gear72meshes with drive gear78and rotates gear drive78down the main ramp ring100thereby lowering the frame50down towards the base21. More specifically, the drive gear main ramp86(most clearly shown inFIG. 7) rides down the corresponding main ramp ring106as is shown progressively inFIGS. 12aand12b.

A reaction torque stopping rotation of the drive gear78is created at the interface of the reaction face82of the drive gear78with the reaction face222of the secondary ramp ring220as illustrated inFIG. 12b. With the drive gear78now held from further movement with respect to the secondary ramp ring220and hence the base21, the worm gear72and hence the housing40, the frame50and the entire mirror head51rotates with respect to the base21as is illustrated in the transition fromFIG. 12bto12c.

InFIG. 12cit can be seen that the frame50is reaching the detent form by detent features57and24. In the transition fromFIG. 12ctoFIG. 12d, it can be seen that the frame50fully engages the detents and then, with the detents holding the frame50against further movement with respect to the base21, the drive gear78rotates with respect to the housing40such that the electric stall ring110and the manual fold ring120both re-engage. More specifically, the electric stall ring stop115engages the drive gear electric fold ring stop81as is shown progressively fromFIG. 12dto12e. At the same time, the manual fold ring pushing face122moves up into position adjacent the main ramp ring push face102, leaving the mechanism stalled in the drive position shown inFIG. 12e.

Electric Fold in from the Drive to Park Position

Referring now toFIGS. 13ato13f, electric fold in from the drive to the park position will now be described. Referring first toFIG. 13a, power is applied to the motor75causing the worm gear72to rotate the drive gear78. It can be seen inFIG. 13bthat the ramp88on the protrusion79of the drive gear78has reached the ramp123of the manual fold ring120. As the drive gear78continues to rotate with respect to the housing and hence the manual fold ring120, it starts to push the manual fold ring120downwards against the weak spring force provided by the manual fold spring130most clearly shown diagrammatically inFIG. 9b.

Referring now toFIG. 13c, it can be seen that the manual fold ring120has disengaged from the main ramp ring so that the manual fold ring120is effectively no longer splined or otherwise locked to rotate with the housing40.

In the transition fromFIG. 13cto13dit can be seen that the drive gear78goes up the main ramp ring as the frame50slides up the detents24on the base21.

FIG. 13eshows the park stop54of the frame50reaching the base rearward folds (park) end stop28. Finally, in the transition fromFIG. 13eto13fit can be seen that the drive gear78rides up the main ramp ring100to take up any manufacturing clearances or tolerances lifting the frame50up and stalling the mechanism in a position shown inFIG. 13f.

Manual Fold Out after Electric Fold in (Manual Re-Deploy)

Referring now toFIGS. 14ato14e, manual fold out of the mirror head back to the drive position after electric fold in will now be described. Referring first toFIGS. 14aand14b, as a person pushes on the mirror head51and therefore the frame50, this produces a force on the worm gear72which in turn pushes against the drive gear78. Given that the main ramp ring is at this point engaged with the main ramp ring100, the ramp ring100rides up the steep clutch ramp107until the knee108is reached as is shown inFIG. 14b. In the transition from14bto14c, it can be seen that the main ramp ring100now moves up under the action of spring104most clearly shown inFIG. 9b. [CHECK WITH CLIENT—does the spring101or104bias the main ramp ring100upwards or downwards?].

As the main ramp ring100moves upwards, it also moves forward as indicated by the arrow inFIG. 14c.

With the clutch now disengaged, the frame50rotates to the drive position as is shown progressively fromFIGS. 14cto14e. InFIG. 14e, the detents24and57can be seen re-engaging. The main ramp ring100also moves further upwards.

Alternative Manual Fold Torque Transmission Member

Referring now toFIG. 10aan alternative manual fold torque transmission member is shown. With this alternative, an actuator125is provided. This actuator performs the same function that the ramp123performs in the manual fold ring120described with reference toFIG. 13afor instance. That is, the actuator125actuates the manual fold torque transmission member120upwards and downwards so as to engage or disengage it with the main ramp ring100.

Alternative Electric Stall Ring

Referring now toFIG. 10b, an alternative electric stall system110is shown. With this alternative, the relative rotational positions between the drive gear78and the electric fold ring110is sensed through elements105and116as shown inFIG. 10b. Sensor elements105and116(which may include a limit switch) replace the electric stall ring ramps and stops114and115shown inFIG. 8a. This alternative electric stall system detects a relative rotational position between the housing40and the drive gear78and stalls the drive gear78by cutting power to the motor in the position shown inFIG. 12e.

With the embodiment of the invention described, a conventional manual fold detent system is used which enhances vibration performance and manual folding functions. Furthermore, because the power fold drive train is only operably connected between the frame50and base21during electric operation, all loads, including wind load, road transmitted loads, and static loads are transferred from the frame50to the base21through the manual detent system and the power fold mechanism is isolated from these loads. As a result, the power fold drive train and other components do not have the same strength and rigidity requirements of a conventional power fold system.

The operating logic of the power folding system described above is improved compared to prior art folding mirror heads. Combinations of manual and electric folding functions behave as expected, with the mirror head and frame being able to be returned to the drive position in one or two activations of a vehicle cabin mounted switch.

The provision of a park position detent that engages after manual fold in is a useful, but not essential feature as it positively holds the mirror in the parked position. This is important during car washing and during loading of vehicles onto trucks, trains or other vehicles.

The fold system described above has good vibration performance including after it has been manually folded to the drive position. Clutch reset is logical and does not result in clunking noise. There are no delays caused by clutch reset.

Having the electric folding mechanism out of the load path (other than when electrically actuating the mirror head) results in identical performance for both manual and power fold systems. This is in stark contrast to most power fold systems in which there is a summing of torques from both the manual and power fold systems during at least some manual operations.

While the present invention has been described in terms of preferred embodiments in order to facilitate better understanding of the invention, it should be appreciated that various modifications can be made without departing from the principles of the invention. Therefore, the invention should be understood to include all such modifications within its scope.