MXPA00001635A - Vehicle door latch with reduced release effort - Google Patents

Abstract

A latch assembly (10) has a housing (12) having a mouth (14). A detent fork (16) is pivotally mounted within the housing (12) to cooperate with the mouth (14) to pivot between an open and closed condition for receiving, engaging and cinching a keeper (60) of a striker. The detent fork (16) is biased in the open condition. A pivotally mounted pawl (24) is biased for engagement with a pin (26). Pin (26) is slidably mounted within a guideway (38) and positioned between the detent fork (16) and the pawl (24). The pin (26) cooperates with the pawl (24) to retain the detent fork (16) in the closed condition. The pin (26) rolls between the pawl (24) and detent fork (16) as the pawl (24) is rotated in a releasing sense to disengage the detent fork (16).

Description

PICAPORTE FOR VEHICLE DOOR WITH REDUCED RELEASE EFFORT Field of the Invention This invention relates to a door latch for a vehicle. In particular, this invention relates to a latch that can be released with a relatively small amount of effort.

Background of the Invention Door latch systems for vehicle doors are well known in the art. Typically, a car hood or luggage compartment cover will have a latch for coupling and cinching on a hook or belt track. The latch will have a pivotably mounted detent fork that engages a ratchet in a toothed relationship. The detent fork cooperates with a mouth of the housing to pivotally move between an open and closed condition to receive, engage and cinch a fastener of a raceway or hook. The detent fork has a cam surface having recessed surfaces. When the fork of Ref.32802 detent engages the fastener of an engager, the detent fork rotates in a securing direction and the ratchet travels along the surface of the cam to retain the detent fork in the closed and cinched conditions . To release the latch, the ratchet is rotated to uncouple from the detent fork. The ratchet must overcome the frictional engagement between the ratchet and the detent fork. Additionally, the pawl must rotate the detent fork counterclockwise before the pawl becomes uncoupled. The amount of effort required to release the detent fork is therefore proportional to the size of the spring which deflects or tilts the detent fork and the length of the ratchet lever arm. The lever arm of the ratchet can be lengthened to minimize stress. However, the race or play of the release handle is also increased or will require additional links to operate, both of which may not be desirable. Alternatively, the spring resistance could be reduced to meet the minimum FMVSS. FR-A-2 472 651 discloses a latch having a bolt mounted between the detent fork and the ratchet. However, this pin is mounted elastically to the pivot point of the ratchet. Accordingly, the effort required to release the latch includes the effort to overcome the deflection or inclination of the spring.

Brief Description of the Invention The disadvantages of the prior art can be overcome by providing a latch assembly for a vehicle having a mechanism to reduce the effort to release a ratchet from a detent fork. According to one aspect of the invention, a latch assembly having a housing having a mouth is provided. A detent fork is mounted within the housing to cooperate with the spout for pivotal movement between an open and closed condition for receiving, engaging and cinching a fastener of a raceway or hook. The detent fork is deflected or tilted towards the open condition. A pivotally mounted ratchet is deflected or tilted for engagement with a bolt. The bolt is slidably mounted within a guide and placed between the detent fork and the ratchet. The bolt cooperates with the pawl to retain the detent fork in the closed condition. The bolt rotates between the pawl and the detent fork when the pawl is rotated in a release direction to uncouple the detent fork.

Description of the Drawings In the drawings illustrating embodiments of the invention, Figure 1 is a perspective view of the latch assembly of the present invention, with the front cover plate removed, Figure 2 is a front elevational view of the latch assembly of the latch assembly. Figure 1 in a fully open condition; Figure 3 is a front elevational view of the latch assembly of Figure 1; Figure 4 is a front elevational view of the latch assembly of Figure 1 in a secondary closed condition; Figure 5 is a front elevational view of the latch assembly of Figure 1 in a primary closed condition; Figure 6 is a front elevational view of the latch assembly of Figure 1 in a release condition; Figure 7 is a front elevational view of the latch assembly of Figure 1 in a release condition; Figure 8 is a front elevation view of Figure 1 in a near-release condition; Figure 9 is a front elevational view of the latch assembly of Figure 1 in a released or open condition.

Description of the invention The latch 10 of the present invention is illustrated generally in FIG. 1. The latch 10 has a housing 12 having a mouth 14. A detent fork 16 is pivotally mounted on the housing 12. The spring 18 is connected between the yoke catch 16 and housing 12 for deflecting or tilting catch fork 16 to an open condition. The detent fork 16 cooperates with the mouth 14 to receive, engage and cinch a fastener of a raceway or hook. The shock absorbers 20 and 22 limit the rotary travel of the retaining fork 16. The shock absorber 20 limits the closing travel of the retaining fork 16 and places the retaining fork 16 in a closed condition and protects the latch 10 in the cases of overload of the closure. The damper 22 limits the opening stroke and places the detent fork 16 in an open condition ready to receive the treadle or hook. The pawl 24 is pivotally mounted on the housing 12 on an opposite side of the mouth 14 from the detent fork 16. The pawl 24 in cooperation with the bolt 26 coact with the detent fork 16 in a serrated manner, as will be described later . The pawl 24 has a spring 28 which deflects or tilts the pawl in a securing direction to engage the bolt 26. The housing 12 has dampers 30 and 32 which limit the rotational path of the pawl 24. The dashpot 30 limits the travel of the pawl. closure, while the buffer 32 limits the opening stroke. Referring to Figure 2, the detent fork 16 is pivotally mounted to the housing in the bolt 34 and rotates either in a securing direction or in a release direction. The pawl 24 is pivotally mounted to the housing 12 in the bolt 36. The opposing internal faces of the housing 12 have a guide or notch 38 for receiving the bolt 26. The guide 38 places the bolt 26 substantially parallel to the bolts 34 and 36 and allows that the bolt 26 slides lengthwise between a detent fork engagement position and a release or disengagement position. The detent fork 16 has a cam surface 40 having a secondary retainer 42 and a primary retainer 44. Behind the secondary retainer 42 is an arcuate secondary recess surface 46. Similarly, behind the primary seal 44 is an arcuate primary embedment surface 48. The embedding surfaces 46 and 48 each have a radius approximately equal to the radius of the bolt 26 to receive the pin 26 in a plug-in or telescopic manner. The pawl 24 has a cam surface 50. The surface of the cam 50 has a curved embedment 52 that joins smoothly with an arcuate rotating surface 54, ending in a release detent 56. The arcuate embedment 52 and the arcuate rotating surface 54 each have a radius approximately equal to that of the bolt 26. Embedment 52 has an extension enough circumferential to receive and protect the bolt 26. The bolt 26 is preferably dimensioned in accordance with the radial lengths as shown in Figure 3. The radial length R3 must be sufficient to engage the detent fork 16 in a toothed coupling. Additionally, the diameter of the bolt (R3-R1) is related to the angular travel of the pawl a and the angular travel of the bolt 26 a2 as follows: . { a / a2} =. { 1 + R3 / R1} When the latch receives the fastener 60 as illustrated in Figure 4, the movement The closure will push the retainer fork 16 to rotate in a securing direction. The leading edge 62 of the detent fork 16 frictionally engages the bolt 26 and will push the bolt 26 toward the embedment 52 of the cam surface 50. The detent fork 16 will travel relatively towards the bolt 26 until the bolt 26 passes into the secondary retainer 42. The deflection or inclination of the spring 28 will cause the pawl 24 to rotate in a securing direction by pushing the bolt 26 in engagement with the embedment Secondary 46. In this position, the bolt 26 makes butt contact with the detent fork 16, cooperating with the pawl 24 to resist the counter rotation (i.e., in a releasing direction) of the detent fork 16 retaining the detent fork 16 in a condition fixed with secondary latch.

The additional closing rotation of the detent fork 16 in a closing direction will push the pawl 24 against the deflection or inclination of the spring 28. The surface of the cam 40 will frictionally engage the bolt 26 when the detent fork 16 continues to rotate beyond the detent 44. Again the deflection or inclination of the spring 28 will cause the pawl 24 to rotate by pushing the bolt 26 in engagement with the primary embedment 48 to a closed condition. In this second closed condition, the detent fork 16 is in full engagement with the gripper or gripper holder 60. The pawl 24 and the bolt 26 abutting the detent fork 16 cooperate to resist rotation backward of the detent fork 16. Referring to Figures 6 and 9, the latch 10 is released by applying a force of F release to the end remote from the pawl 24 in a release direction. The rotation of the pawl in the release direction will cause the bolt 26 to rotate relative to it. The bolt 26 will rotate along the surface of the cam 50 from the embedment 52 toward the rotating surface 54. Similarly, the bolt 26 will travel along the surface of the cam 40 from the embedment surface 48 toward the retainer 44 until it is decoupled with the retainer fork 16. Since this movement is a rotational movement, there are minimal friction forces involved and it requires a relatively minimal amount of effort. Preferably, the bolt 26 rotatably engages the surface of the cam 40 until the bolt 26 abuts the release latch 56 which will place the bolt 26 in a condition close to that of the release. As is evident, the length of the surface of the cam 40 and the circumferential extension of the bolt 26 are related to the proper positioning of the bolt 26 in the condition close to the release. In this condition close to the release, the bolt 26 is fully protected within the rotary surface 54. The pawl 24 and the bolt 26 will be in a condition on the center and as such will resist the opposite rotation of the detent fork 16. release latch 56 will prevent further rotation of the bolt 26. Continuous application of the release force F will cause the bolt 26 to slide a relatively short distance from a condition about the center to beyond the center and will release the detent fork 16. releasing the fastener 60 from the raceway or hook. In this way, the entire effort of the latch 10 is reduced but a final release effort is required to fully release the latch preventing an inadvertent or accidental release. The foregoing specific embodiment is illustrative of the practice of the present invention. It should be understood, however, that other advantages known or apparent to those skilled in the art or described herein may be employed without departing from the scope of the invention as defined by the appended claims.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Having described the invention as above, property is claimed as contained in the following

Claims (9)

1. A latch assembly, comprising: a housing having a mouth, a detent fork pivotally mounted within the housing for cooperating with the mouth, for pivotally moving between an open condition and a closed condition for receiving, engaging and cinching a fastener an engager, the detent fork is biased or tilted to the open condition, a bolt slidably mounted and slidable between a detent fork coupling position and an uncoupled position, and a pivotally mounted ratchet engaging the bolt, the diverted ratchet or inclined to push the bolt into the engagement position of the detent fork, the bolt positioned between the detent fork and the pawl and cooperating with the pawl to retain the detent fork in a closed condition during rotation of the retainer fork in a sense of securing towards the closed position, characterized in that the pin is slidably mounted within a guide so that it rotates between the pawl and the detent fork from the engaging position of the detent fork to a position close to that of release when the pawl is rotated in a release direction, and rotation The additional ratchet in the direction of the release pushes the pin to move from the position close to the release to the uncoupled position that releases the retainer fork.

2. A latch assembly according to claim 1, characterized in that the pawl has a cam surface having a release latch, the bolt rotatably engages the cam surface and abuts the release latch when the pawl rotates in a sense of liberation to the position close to liberation.

3. A ratchet assembly according to claim 1, characterized in that the pawl has a cam surface having a release latch at one end thereof and an embedment at an opposite end thereof, the bolt rotatably engages the cam surface between the release catch and the securing retainer when the ratchet is rotated.

4. A latch assembly according to claim 3, characterized in that the bolt engages the embedment when the detent fork is retained in the closed condition and the bolt engages the release latch when the pawl is rotated further in the releasing direction that releases the retainer fork.

5. A latch assembly according to any preceding claim, characterized in that the detent fork has a primary retainer for bolt engagement, to retain the detent fork in the closed condition and a secondary retainer for bolt engagement, to retain the retainer fork in a fixed condition with secondary latch.

6. A latch assembly, comprising: a housing having a mouth, a detent fork pivotally mounted within the housing for cooperating with the mouth to pivotally move between an open condition and a closed condition to receive, engage and cinch a fastener of an engaging means, the detent fork deflected or tilted to the open condition, a bolt slidably mounted between a detent fork engagement position and an uncoupled position, and a pivotally mounted ratchet engaging the bolt, the diverted or inclined ratchet for pushing the bolt to the engagement position of the detent fork, the bolt positioned between the detent fork and the pawl and cooperating with the pawl to retain the detent fork in a closed condition during rotation of the detent fork in a sense of securing to the closed position, characterized in that the bolt is slidably mounted It is arranged within a guide and rotates between the pawl and the detent fork from the engaging position of the detent fork to the decoupling position releasing the detent fork when the pawl is rotated in a release direction.

7. A latch assembly according to claim 6, characterized in that the pawl has a cam surface having a recess at one end, the bolt rotatably engages the cam surface and makes butt contact with the recess when the pawl rotates in a sense of refinement.

8. A latch assembly according to claim 7, characterized in that the bolt engages the embedment when the detent fork is retained in the closed condition.

9. A latch assembly according to claim 8, characterized in that the detent fork has a primary retainer for bolt engagement, to retain the detent fork in the closed condition and a secondary retainer for the bolt engagement, to retain the retainer fork in a fixed condition with secondary latch.