Vehicle door latch

Abstract: A vehicle door latch (10) has a fork bolt lever (30) that is latched by a detent lever (32). The detent lever is operated by an intermittent lever (34) that is operated by a transfer lever (44) that is actuated by inside and outside door handles via operating levers (50,56). The door latch includes with a locking lever (40) that disconnects the door handles from the intermittent lever when it is in the locked position. The door latch also includes an interlock between the intermittent lever and the locking lever that is automatically engaged in response to the position of the detent so that the door latch cannot be locked when the fork bolt lever is in an unlatched position. Consequently the door latch can only be locked when the door is closed and the fork bolt lever is in a latched position. This prevents the driver from locking his or her keys in the vehicle.

Description: This invention relates to vehicle door latches and more particularly to vehicle door latches that are capable of being locked from outside the vehicle. Vehicle door latches customarily include a lock mechanism that prevents operation of the door latch so that the vehicle door cannot be opened by persons inside the vehicle unintentionally or by persons outside the vehicle who are not authorised. The door lock mechanism itself can also be operated from inside as well as from outside the vehicle. The door lock mechanism is usually operated from inside the vehicle by a slide or a sill button that is actuated manually and also electrically in some vehicles. The door lock mechanism is usually operated from outside the vehicle by a key and key lock cylinder or some other device that keeps intruders locked out of the vehicle. A long standing problem associated with lockable vehicle door latches is that of locking the keys inside the vehicle. This problem results from the door latch having the capability of being locked when it is unlatched. Thus the driver or passenger can lock the door by actuating the inside lock operator before the door is shut and avoid the inconvenience of using a key. Various solutions have been proposed for this "keyless" locking problem. There are generally two types of mechanisms for locking the vehicle door latch. In one type, a locking member blocks and/or immobilises a member of the latch mechanism so that the inside and outside door handles as well as the internal parts of the door latch cannot be moved. One solution for the keyless locking problem in these blocking type door lock mechanisms is disclosed in US-A-3,781,045 for a motor vehicle door latch with a lock mechanism that is only actuatable with the vehicle door closed. This known door latch has a detent or keeper that carries a fixed crank arm. The crank arm has a projection that prevents the lock mechanism from being engaged in all but the closed position of the door to prevent the user from locking his or her keys in the vehicle. The second type of mechanism for locking the door latch is generally known as the free wheeling type. In this type, the lock mechanism disconnects the latching mechanism when it is engaged so that the motion of neither door handles is transferred to the detent lever and consequently operation of the door handles is ineffective. A vehicle door latch of this type is disclosed in US-A-4,756,563. Solutions have also been proposed for the keyless locking problem in connection with vehicle door latches that have freewheeling type lock mechanisms. See, for example, US-A-3,840,258 for a motor vehicle door latch and US-A-5,054,827 for a vehicle door latch. These solutions, however do not prevent keyless door locking. They merely require actuation of the outside door handle or other outside latch operator with the hope that this extra operation will prevent unintentional locking of the keys in the vehicle. The object of this invention is to provide a vehicle door latch that has a freewheeling type lock mechanism that simply cannot be engaged when the door latch is unlatched under any circumstances so that the vehicle user cannot lock his or her keys in the vehicle. To this end, a vehicle door latch in accordance with the present invention is defined by the features specified in claims 1 and 4. A feature of the vehicle door latch of the invention is that the door latch has an interlock mechanism that is automatically actuated in response to the position of the fork bolt lever to prevent engagement of the lock mechanism when door latch is unlatched. The present invention may also provide a vehicle door latch that has a fork bolt lever that automatically actuates an interlock between a member of the latching mechanism and a member of lock mechanism when the fork bolt lever is in an unlatched position so that the locking mechanism cannot be engaged when the door latch in unlatched. The present invention may further provide a vehicle door latch that has a freewheel type lock mechanism and an interlock mechanism that is automatically engaged when the vehicle door latch is unlatched and that cannot be disengaged when the vehicle door latch is unlatched so that keyless locking is not possible. The present invention will now by described, by way of example, with reference to the following description taken in conjunction with the accompanying drawings wherein like references refer to like parts and wherein:- Figure 1 is a front view of a vehicle door latch in accordance with the present invention, with the latch shown in an unlatched and unlocked condition; Figure 2 is section taken substantially along the line 2-2 of Figure 1 looking in the direction of the arrows; Figure 3 is a fragmentary front view of the vehicle door latch of Figure 1 showing parts of the vehicle door latch in full and intermediate latched positions; Figure 4 is a fragmentary front view of the vehicle door latch of Figure 1 showing parts of the vehicle door latch in an unlatched and locked condition; and Figure 5 is an exploded perspective view of the vehicle door latch that is shown in Figures 1-4. Referring now to the drawing and more particularly to the exploded perspective view of Figure 5, the vehicle door latch 10 is the same basic arrangement as the vehicle door latches that are disclosed in US-A-4,756,563 and US-A-5,054,827. The vehicle door latch 10 has a three piece enclosure that comprises plastic housing 12, metal face plate 14 and metal back plate 16. The plastic housing 12 and the metal back plate 16 are held together by three flanged, internally threaded bushings 18, 20 and 22 that are inserted into three holes in the plastic housing 12, then through three aligned holes in the back plate 16 and then flanged over the back plate. The metal face plate 14 has three bolt holes 24 that are aligned with the bushings 18, 20 and 24 when the metal face plate is attached to the plastic housing 12 by a screw 26. The metal face plate 14 and the metal back plate 16 have lower portions below the plastic housing 12 that are held together by a flanged stud 28 that has projecting pins at each end that are inserted in holes in the plates and peened on headed over as best shown in Figure 2. LATCHING MECHANISM The latching mechanism of the vehicle door latch 10 comprises a fork bolt lever 30 and a cooperating detent lever 32 that are pivotally mounted on bushings 20 and 18 respectively and located in a chamber of the plastic housing 12 behind the metal face plate 14. The fork bolt lever 30 is biased in one rotational direction (for example, clockwise) by a coil spring 29. The coil spring 29 is disposed in a curved slot in the plastic housing 12 behind the fork bolt lever 30 and it engages a depending pin 31 of the fork bolt lever 30 at one end. The detent lever 32 is biased in the other rotational direction (counterclockwise) into engagement with the fork bolt lever 30 by a coil spring 33 that surrounds the bushing 18 and that has one end engaging the plastic housing 12 and the other end engaging an ear 35 of the detent lever 32. The detent lever 32 engages the fork bolt lever 30 in its unlatched position as shown in Figure 1 and engages and the holds the fork bolt lever 30 in intermediate and full latched positions against the bias of spring 29 as shown in Figures 3 and 4. The operation is explained more fully below. The latching mechanism further comprises an intermittent lever 34 for operating the detent lever 32. The intermittent lever 34 is located in the chamber of the plastic housing 12 behind the detent lever 32. It has two integral pivot pins 36 and 38. Pivot pin 36 is journalled in a hole in the detent lever 32 so that the detent lever 32 rotates clockwise from the position shown in Figure 3 (and out of latched engagement with the fork bolt lever 30) to the position shown in Figure 1 when the intermittent lever 34 is pulled down. The pivot pin 38 is disposed in a slot of a locking lever 40 so that the locking lever 40 pivots the intermittent lever 34 counterclockwise about pivot pin 36 when the locking lever 40 is rotated clockwise from their respective positions shown in Figure 3 to their respective positions shown in Figure 4. The locking lever 40 is journalled on the stud 28 between the flange 42 thereon and the face plate 14. The operation of the locking lever 40 is explained in greater detail below in connection with the description of the lock mechanism. The latching mechanism further comprises a transfer lever 44 that is journalled on a reduced diameter portion of the stud 28 spaced rearwardly of the flange 42. The transfer lever 44 has an ear 46 at one end that is engagable with an integral, rearwardly projecting tab 48 of the intermittent lever 34 so that the intermittent lever 34 is pulled down when the transfer lever 44 is rotated clockwise as viewed in Figure 5. The latching mechanism further comprises an outside operating lever 50 and a coil return spring 52. The outside operating lever 50 is also journalled on the reduced diameter portion of the stud 28 behind the transfer lever 44. It has a bent tab 54 that engages the ear 46 of the transfer lever 44 so that the outside operating lever 50 rotates the transfer lever 44 clockwise when it is rotated clockwise on stud 28. The outside operating lever 50 is connected by suitable linkage for rotation by an outside door handle (not shown). The coil return spring 52 is disposed around the stud 28 and located between the flange 42 and the transfer lever 44. One end of the coil spring 52 engages the bottom of transfer lever 44 and the other end engages the bottom of the plastic housing 12 above the transfer lever 44 so that the transfer lever 44 and outside operating lever 50 are biased counterclockwise to a rest position where tab 54 engages the bottom of the plastic housing 12. The latching mechanism further comprises an inside operating lever 56 that is pivotally mounted on a flange of the metal face plate 14. The inside operating lever 56 has a tab 58 that engages a second ear 60 of the transfer lever 44 so that the inside operating lever also rotates the transfer lever 44 clockwise when it is rotated counterclockwise. The inside operating lever 56 is connected by suitable linkage for rotation by an inside door handle (not shown). Referring now to Figure 1, the fork bolt lever 30 has a conventional slot or throat 59 for receiving and retaining a striker member, such as that shown in the US patents discussed above, that is attached to the door pillar to latch the door in the closed position (not shown). The fork bolt lever 30 also includes a primary latch shoulder 61, an intermediate latch shoulder 62 and a radially projecting foot 64. The fork bolt lever 30 also has a plastic coating 66 that covers a surface of the slot 59 that is engaged by the striker for energy absorption and quiet operation when the vehicle door is slammed shut. The detent lever 32 has a sector shaped catch 68 that engages the radially projecting foot 64 when the fork bolt lever 30 is in the unlatched position as shown in Figure 1. The sector shaped catch 68 positively engages the primary and intermediate latch shoulders 61 and 62 to hold the fork bolt lever 30 in either full or intermediate latched positions shown in Figures 3 and 4 in solid line and phantom respectively. The detent lever 32 also includes a plastic coating 70 which has a slotted portion that provides an integral bumper 72. The bumper 72 engages the bushing 22 to stop counterclockwise pivoting of the detent lever 32 under the bias of spring 52. This bumper 72 also absorbs energy and quiets operation when the door is slammed shut. The latching mechanism operates as follows. When the door latch 10 in an unlatched and unlocked condition as shown in Figure 1, the fork bolt lever 30 is poised to receive a conventional striker (not shown) that projects into aligned fishmouth slots 73 and 75 of the plastic housing 12 and the metal face plate 14 when the door is shut. The entering striker engages the plastic coating 66 at the back of the throat 59 and rotates the fork bolt lever 30 counterclockwise against the bias of spring 29 until the fork bolt lever 30 is rotated to the full latch position shown in solid line in Figure 3 where the fork bolt lever 30 captures the striker in the throat 59. The fork bolt lever 30 is held in the full latch position by the catch 68 of the detent lever 32 engaging the primary latch shoulder 61 of the fork bolt lever 30. The catch 68 rides along the periphery of the fork bolt lever 30 under the bias of spring 52 as the fork bolt lever 30 rotates counterclockwise from the unlatched position shown in Figure 1 to the full latch position shown in Figure 3. During this travel, the catch 68 rides under the foot 64 into engagement with the intermediate latching shoulder 62 and then under the coated portion into engagement with the primary latching shoulder 61. It is to be noted that the engagement of the catch 68 with the intermediate latching shoulder 62 is sufficient to hold the vehicle door closed in the event that the vehicle door is shut completely so that the catch 68 engages the primary latch shoulder 61. The vehicle door latch 10 is unlatched so that the vehicle door can be opened by operating either the inside or the outside door handle to rotate the transfer lever 44 clockwise and the ear 46 down as viewed in Figure 5. The ear 46 engages projection (tab) 48 of intermittent lever 34 as shown in Figure 2 and pulls the intermittent lever down from the full latch position shown in Figure 3 to the unlatch position shown in Figure 1. As the intermittent lever 34 is pull down, it rotates the detent lever 32 clockwise against the bias of spring 52 from the latch position shown in Figure 3 to the unlatch position shown in Figure 1. The fork bolt lever 30 is then free to rotate counterclockwise under the bias of spring 29 from the full latch position shown in solid line in Figure 3 to the unlatch position shown in Figure 1 as the striker is pulled out of the aligned fishmouth slots 73 and 75 when the vehicle door is opened. LOCKING MECHANISM Returning to Figure 5, the vehicle door latch 10 includes a freewheeling type lock mechanism for disconnecting the latching mechanism so that operation of either the inside door handle or the outside door handle is ineffective in unlatching the detent liner 32. The lock mechanism comprises the locking lever 40 that is pivotally mounted on the stud 28 between the flange 42 and the metal face plate 14. As indicated above, the locking lever 40 is also connected to the intermittent lever 34 by a pin and slot arrangement that allows these two parts to translate and pivot with respect to each other. The locking lever 40 pivots on the stud 28 between an unlocked position shown in Figures 1, 2 and 3 and a locked position shown in Figure 4. The locking lever 40 is held in the unlocked position by a coil spring 74 that has one end mounted on the plastic housing 12 and the other end engaging a first detent notch 76 in the plastic locking lever 40. The plastic locking lever 40 pivots clockwise from this position to the locked position shown in Figure 4. The end of the coil spring 74 engages a second detent notch 78 in the locking lever 40 to hold it in the locked position. The lock mechanism further comprises inside and outside lock operating levers 80 and 82 for pivoting the plastic locking lever 40 back and forth between the locked and unlocked positions. The inside lock operating lever 80 is pivotally mounted on the flange of the metal face plate 14 in front of the inside operating lever 56 for unlatching the door. It includes a tab 84 that engages in a slot 85 in one end of the plastic locking lever 40 so that the plastic locking lever 40 is pivoted clockwise from the unlocked position shown in Figure 3 to the locked position shown in Figure 4 when the inside lock operating lever 80 is pivoted counterclockwise by an inside door handle or slide (not shown). The outside lock operating lever 82 is pivotally mounted on the stud 28 between the locking lever 40 and the face plate 14. The outside lock operating lever 82 has a sector shaped cut-out 86 that receives an integral projection 88 of the locking lever 40. This forms a lost motion connection between the outside lock operating lever 82 and the locking lever 40 so that the key and key cylinder can be returned to a neutral position after the locking lever 40 is rotated one way or the other. In any event, the locking lever 40 can also be rotated clockwise from the unlocked position shown in Figure 3 to the locked position shown in Figure 4 by rotating the outside lock operating lever 82 clockwise from the unlocked position shown in Figure 3 to the locked position shown in Figure 4 and back through suitable linkage by a conventional key lock cylinder (not shown). The lock mechanism operates as follows. When the vehicle door latch 10 is in a latched condition as shown in Figure 3, the lock mechanism is actuated by rotating the locking lever 40 clockwise from the unlocked position shown in Figure 3 to the locked position shown in Figure 4. As indicated above this can be accomplished through rotation of the inside lock operating lever 80 by an inside sill button or lock slide or by rotation of the outside lock operating lever 82 by turning a key in the key lock cylinder. Clockwise rotation of the locking lever 40 also rotates the intermittent lever 34 counterclockwise about the pivot pin 36 that is journalled in the detent lever 32 due to the engagement of the second pivot pin 38 of the intermittent lever 34 in the slot of the locking lever 40. The intermittent lever 34 is rotated counterclockwise from the unlocked position shown in Figure 3 to the locked position shown in Figure 4 moving the projection (tab) 48 out from under the ear 46 of the transfer lever 44. Consequently when the door handles are operated so as to rotate the transfer lever 44 clockwise to the unlatching position, the ear 46 simply bypasses the projection 48 without transferring any motion to the intermittent lever 34. In other words the transfer lever 44 simply free wheels so that operation of the door handles is ineffective. The lock mechanism is unlocked simply by rotating the locking lever 40 counterclockwise back to the unlocked position shown in Figure 3 where the projection 48 is beneath the ear 46 of the transfer lever 44 so that clockwise rotation of the transfer lever 44 pulls the intermittent lever 34 and the detent lever 32 down to the disengaged position shown in Figure 1. INTERLOCK MECHANISM The vehicle door latch 10 also includes an interlock mechanism that permits the vehicle door latch 10 to be locked when the door latch is in a latched condition as shown in Figure 3 but which does not permit the vehicle door latch 10 to a locked when the door latch 10 is in an unlatched condition as shown in Figure 1. The interlock mechanism comprises the fork bolt lever 30 which has the radially projecting foot 64, the detent lever 32 that is spring biased into engagement with the fork bolt lever 30, the intermittent lever 34 that is pivoted on and positioned by the detent lever 32, the locking lever 40 that is connected to the intermittent lever 34 by an arrangement that allows these two parts to translate and pivot with respect to each other, and an integral interlock projection 90 of the locking lever 40 that limits pivotal movement of the intermittent lever 34 with respect to the locking lever 40 in certain circumstances. The integral interlock projection 90 which is best shown in Figures 2 and 5 is positioned at the bottom right hand side of the locking lever 40 as shown in Figures 1, 3 and 4. In such a position, the integral interlock projection 90 is located out of the path of movement of the intermittent lever 34 when the door latch 10 is in a latched condition and the locking lever 40 is actuated. Returning now to Figure 3, the door latch 10 is shown in a latched and unlocked condition. In this condition, the detent lever 32 is biased against the bushing 22 by the coil spring 33 locating the pivot hole for the pivot pin 36 of the intermittent lever 34. In this instance the intermittent lever 34 is in an upper position in the housing 12 that can be noted from the high position of the second pivot pin 38 of the intermittent lever 34 in the slot of the locking lever 40. In this upper position, the intermittent lever 34 bypasses the interlock projection 90 as it pivots from the unlocked position shown in Figure 3 to the locked position shown in Figure 4. In other words, the interlock projection 90 is out of the path of movement of the intermittent lever 34 as it pivots relative to the detent lever 32 and moves relative to the locking lever 40 so as to move from the unlocked position of Figure 3 to the locked position of Figure 4. On the other hand, this same lock projection 90 prevents actuation of the locking mechanism when the fork bolt lever 30 is in an unlatched condition as shown in Figure 1. In this unlatched condition, the foot 64 of the fork bolt lever 30 holds the detent lever 32 in an unlatched position shown in Figure 1 where the detent lever 32 is rotated clockwise from the latched position shown in Figure 3. This lowers the pivot hole for the pivot pin 36 and lowers the intermittent lever 34 in the housing 12 as shown by the low position of the second pivot pin 38 in the slot of the locking lever 40. The lower end of the intermittent lever 34 is now located adjacent the interlock projection 90 due to the lower positioning of the intermittent lever 34 in the housing 12 by the detent lever 32 and foot 64 of the fork bolt lever 30. Consequently, the locking mechanism cannot be actuated because the interlock projection 90 interferes and locks up the intermittent lever 34 and the locking lever 40 in response to clockwise rotation of the locking lever 40. In other words the interlock projection 90 is now located in the path of movement of the intermittent lever 34. Moreover the interlock mechanism that is automatically engaged by the unlatched position of the fork bolt lever 30 cannot be disengaged by operating the inside or the outside operating levers 56 and 50 that are connected to the door handles or similar operators, because the transfer lever 44 cannot raise the intermittent lever 34 above the projection 90. While the interlock projection 90 is illustrated as being an integral part of the locking lever 40 that interferes with movement of the intermittent lever 34 to the locked position in certain circumstances, it is also conceivable that the interlock projection 90 can be made an integral part of the intermittent lever 34 that interferes with movement of the locking lever 40 to the locked position.

Claims: A vehicle door latch (10) having a free wheel lock mechanism and an interlock mechanism that prevents initiation of the free wheel condition when the vehicle door latch is in an unlatched condition comprising a fork bolt (30) that is moveable between a latched position and an unlatched position, the fork bolt having a latch shoulder (61) that is engaged by a detent (32) to hold it in the latched position and a conformation (64) that engages and repositions the detent when it is in the unlatched position; an intermittent member (34) that is positioned by the detent and operatively connected to the detent for disengaging the detent from the latch shoulder of the fork bolt; a moveable locking member (40) that is moveable relative to the intermittent member and operatively connected to the intermittent lever for moving the intermittent member between an unlocked position and a locked position corresponding to the free wheel condition; and an interlock conformation (90) on one of the intermittent member and the locking member that limits movement of the intermittent member relative to the locking member when the detent engages the conformation of the fork bolt so that the locking member cannot move the intermittent member to the locked position when the fork bolt is in the unlatched position. A vehicle door latch as claimed in claim 1, wherein the interlock conformation (90) is located on the locking member (40) so that it is out of the path of movement of the intermittent member (34) when the detent (32) engages the latch shoulder (60) of the fork bolt (30). A vehicle door latch as claimed in claim 1 or claim 2, wherein the detent (32) locates the intermittent member in an upper position with respect to the locking member (40) when the detent engages the latch shoulder (60) of the fork bolt (30) so that the interlock conformation (90) is bypassed as the intermittent member (34) moves from an unlocked position to a locked position. A vehicle door latch (10) having a free wheel lock mechanism and an interlock mechanism that prevents initiation of the free wheel condition when the vehicle door latch is in an unlatched condition comprising a fork bolt lever (30) that is rotatable between a latched position and an unlatched position and that has a radially projecting foot (64); a detent lever (32) that is rotatable between a first position holding the fork bolt lever in the latched position and a second position engaging the radially projecting foot of the fork bolt lever when the fork bolt lever is in the unlatched position; an intermittent lever (34) that is pivoted on and positioned by the detent lever; a locking lever (40) that is rotatable between an unlocked position and a locked position and that is connected to the intermittent lever by an arrangement that allows these two parts to translate and pivot with respect to each other; and an integral interlock projection (90) on one of the intermittent lever and the locking lever that limits movement of the intermittent lever with respect to the locking lever when the detent lever is in the second position so that the locking lever cannot be rotated to the locked position corresponding to the free wheel condition when the fork bolt lever is in the unlatched position. A vehicle door latch as claimed in claim 4, wherein the integral interlock projection (90) is located on the locking lever (40) so that it is out of the path of movement of the intermittent lever (34) when the detent lever (32) is in the first position. A vehicle door latch as claimed in claim 4 or claim 5, wherein the detent lever (32) locates the intermittent lever (34) in an upper position with respect to the locking lever (40) when the detent lever is in the first position so that the interlock projection (90) is bypassed as the locking lever rotates from an unlocked position to a locked position. A vehicle door latch as claimed in any one of claims 4 to 6, wherein the interlock projection (90) is located on the locking lever (40) and is out of the path of movement of the intermittent lever (34) as it pivots relative to the detent lever (32) and moves relative to the locking lever (40) to move from an unlocked position to a locked position. A vehicle door latch as claimed in any one of claims 4 to 7, wherein the intermittent lever (34) is lowered with respect to the locking lever (40) by the detent lever (32) when the detent lever rotates from the first position to the second position. A vehicle door latch as claimed in claim 8, wherein the foot (64) of the fork bolt lever (30) holds the detent lever (32) in an unlatched position rotated in one rotational direction from the latched position. A vehicle door latch as claimed in claim 8 or claim 9, wherein the interlock projection (90) is on the locking lever (40) and the lower end of the intermittent lever (34) is located adjacent the interlock projection when the intermittent lever is lowered with respect to the locking lever by the detent lever (32) when the detent lever rotates from the first position to the second position. A vehicle door latch as claimed in any one of claims 8 to 10, wherein the interlock projection (90) interferes with and locks up the intermittent lever (34) and the locking lever (40) in response to rotation of the locking lever in one rotational direction. A vehicle door latch as claimed in claim 8, wherein the interlock projection (90) is on the locking lever (40) and located in the path of movement of the intermittent lever (34).

Inventors: DZURKO THOMAS ADAM, REELHORN JOHN FREDERICK, RIMBEY RONALD PAUL, DZURKO, THOMAS ADAM, REELHORN, JOHN FREDERICK, RIMBEY, RONALD PAUL
Applicants: GEN MOTORS CORP, GENERAL MOTORS CORPORATION
Application year: 1993
Main classification: E05B65
IPC codes: E05B15, E05B17, E05B65, E05B63