Hood Latch

Abstract

A latch assembly for releasably latching a hinged closure structure to a vehicle body compartment structure. The latch assembly comprises keeper elements engageable by latching levers of a latch mechanism. The latching levers, of which there are two, are paired with pawls effective to hold the levers in latched condition. Each of the latching levers and the respective pawl engageable therewith have opposed cam surfaces adapted to coact when the latching lever is moved toward latching position with its pawl displaced for any reason from latch lever holding position thereby to urge the pawl into such holding position.

Description

BACKGROUND OF THE INVENTION

The present invention is concerned with a latch assembly for releasably latching a hinged closure structure such as a vehicle hood to a vehicle body compartment structure such as the compartment in which the engine is housed. Most hood latch assemblies include two latches or latching levers, one of which is a primary latch to hold the hinged closure or hood in fully latched condition. The other or secondary latch has the function of preventing the hinged closure or hood from flying upward in the event the primary latch is not properly latched or fails.

Improperly latched hoods are usually the result of insufficient force being applied in a closing direction to overcome the resistance of the hood counterbalancing springs so that the hood does not reach a fully closed position. It is also possible, however, that a failure or malfunction of the latch mechanism could result in an improperly latched hood.

The latch mechanisms frequently comprise pivoted latching levers that are held in latched condition by pivoted detents or pawls. The detents or pawls are coupled to a release member for movement out of latching lever holding position. Generally, the latching levers are spring-loaded in unlatching direction and the detents or pawls are spring-loaded in latching lever engagement direction. This combination of pivotal and spring-loaded members depends for complete operativeness on free pivotal movement of the members about the several pivot shafts or studs involved.

Hood latches located at the front end of the vehicle are exposed to the elements. Road dust and water spray carrying deicing agents or mud ultimately can cause malfunction of the pivoted members through increased friction resulting from corrosion or sediment buildup between the pivoted members and adjacent surfaces. Protective lubricants deteriorate from engine heat or eventually are washed away. As a result, actuation of the release member to place the mechanism in unlatched condition may not be followed by automatic restoration of pivoted members to their normal position. The restoring springs may not be strong enough to overcome the friction resisting free pivotal movement of the pivoted members of the mechanism.

Accordingly, it is the object of the present invention to provide a latch assembly that is particularly adapted to meet the requirements of a satisfactory hood holddown device even after long exposure to corrosion or other fouling matter.

SUMMARY OF THE INVENTION

The latch assembly embodying the present invention has the function of releasably latching a hinged closure structure, such as a vehicle engine compartment hood, to a vehicle body compartment structure, such as a compartment structure housing the engine. The assembly comprises a latch mechanism mounted on one of the structures, preferably the structure framing the engine compartment, adapted to coact with keeper elements carried on the other structure, preferably the hinged closure or hood.

The latch mechanism is characterized in that it has a primary latching lever to hold the closure structure in fully closed condition and a secondary latching lever to hold the closure structure in a position proximate to fully closed position. The latch mechanism includes a primary pawl engageable with the primary latching lever and a secondary pawl engageable with the secondary latching lever. The secondary and primary pawls are engageable sequentially with the respective secondary and primary latching levers as the closure structure is moved from opened to closed position to hold the respective latching levers in latched condition. Each of the latching levers and the pawl engageable therewith have opposed cam surfaces adapted to abut when the latching lever is moved toward latching position with its respective pawl displaced from latch lever holding position thereby to urge the pawl into said position. A spring means normally biases the latching levers toward unlatched position and the respective pawls toward their latching levers. The mechanism also includes a release means operative to disengage the pawls from the latching levers to permit movement of the closure structure from closed to open position.

DESCRIPTION OF THE DRAWING

Further features and advantages of the present invention will be explained in greater detail making reference to the description, which now follows, reference being had to the drawings, in which:

FIG. 1 is a view of the latch mechanism of the latch assembly embodying the present invention with its component parts concealed within the latch mechanism housing except for portions of the latching levers as the appear when in unlatched conditions;

FIG. 2 is a view of the latch assembly with parts of the latch mechanism housing cutaway to expose the latching levers and pawl and illustrating the relationship of the components when latching is through the secondary latching lever and secondary pawl;

FIG. 3 is a view in part similar to FIG. 2 illustrating the components as they appear when the latching action is through the primary latching lever and primary pawl;

FIG. 4 is an enlarged vertical section through the line 4--4 of FIG. 1;

FIG. 5 is an enlarged horizontal section taken on the line 5--5 of FIG. 1;

FIG. 6 is an enlarged horizontal section taken on the line 6--6 of FIG. 1; and

FIG. 7 is a fragmentary plan view in the direction of the arrow 7 in FIG. 1 .

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, the latch assembly, generally designated 10, embodying the present invention comprises a latch mechanism 11 and coacting keeper elements 12 and 13 (see FIG. 2). The latch mechanism 11 is adapted to be bolted on a structural member (not shown) defining a compartment such as a vehicle engine compartment. The keeper elements 12 and 13 are shown as rolled edges of an aperture in a frame member or panel which is part of a hinged closure structure, such as the hood of a vehicle engine compartment.

It will be understood that the latch mechanism could be mounted on the hood structure and the keeper elements could be part of or mounted on the compartment framing member. The conventional practice, however, is to mount the latch mechanism on the compartment framing structure thus minimizing the free end weight of the closure or hood structure.

The latch mechanism 11 comprises a support or housing 14 formed of a pair of stamped sheet metal members 15 and 16. As best seen in FIG. 1, the support or housing has a vertically elongated nose portion 17 that terminates in tapered sidewalls 18 and 19. The tapered sidewalls function as a pilot to guide the nose portion into the aperture between the keeper elements 12 and 13.

Housed within the nose 17 in a chamber 21 are a pair of latching levers 22 and 23. The latching lever 22 may hereinafter be referred to as the primary latching lever and the lever 23 as the secondary latching lever. Both levers are pivotal about a common pivot shaft 24. The respective ends of the shaft 24 project through the housing forming members 15 and 16 and are riveted over as at 25. Each latching lever has keeper element engaging portions projecting substantially radially outwardly from the pivot axis defined by the shaft 24. As best seen in FIGS. 2 and 3, the keeper element engaging portions of the primary latching lever 22 comprise a slender lower finger 26 and a somewhat thicker L-shaped finger 27 forming a bifurcation 28 adapted to receive the keeper element 12 in latched condition of the closure or hood. The secondary latching lever 23 also has a slender lower finger 29 and a substantially L-shaped upper finger 31 forming a bifurcation 32 adapted to receive keeper element 13.

The primary and secondary latching levers 22 and 23 are pivotal in counterdirections about the pivot shaft 24. The respective latching fingers 26-27 and 29-31 project through openings or slots 33 and 34 in the housing nose portion 17.

Each of the latching levers is paired with a detent or pawl. The primary latching lever 22 is paired with a primary detent or pawl 35 pivotally supported on a shaft or pivot stud 36. Similarly, the second latching lever 23 is paired with a secondary detent or pawl 37 pivotally supported on a shaft 38. As best seen in FIG. 5, the two pivot shafts 37 and 38 are spaced from each other and extend between the housing forming members 15 and 16. The ends of the shaft 37 and 38 are riveted over as at 39 so that these two shafts and the previously described shaft 24 function to hold the members 15 and 16 together to house the latch mechanism components.

Each of the detents or pawls has an abutment engageable with an opposing abutment on its paired latching lever. The primary latching lever has a depending abutment 41 adapted to be engaged on its surface 42 by the face 43 of a hooklike abutment 44 on the primary pawl or detent 35. The secondary latching lever 23 has a depending abutment 45 adapted to be engaged on its face 46 by the face 47 of a hooklike abutment 48 on the secondary pawl 37. The abutting faces 42-43 of the primary latching lever 22 and its paired detent or pawl 35 are rotationally displaced from the corresponding abutting faces 46-47 of the secondary latching lever 23 and its paired detent or pawl 37. This rotational displacement results in sequential engagement of first one and then the other of the pairs of latching levers and pawls as the closure structure is moved from opened to closed position, as will be more fully explained.

The latching lever 22 and its paired detent or pawl 35 as well as the latching lever 23 and its paired detent or pawl 37 are biased by respective springs 49 and 51. As best seen in FIGS. 2 and 3, for example, the spring 49 has a coiled central portion with elongated leg portions 52 and 53 extending therefrom. The leg portion 52 is hooked into an aperture 54 in the primary pawl 35 in relation to the pivot axis 36 of the latter to urge the pawl in a counterclockwise direction as viewed in the drawings. The leg 53 of the spring 49 is hooked over a corner 55 of the primary pawl 22.

By a comparison of FIGS. 2 and 3, it is noted that movement of the latching lever 22 in a clockwise direction results in a windup of the spring 49. The reaction force exerted by the spring 49 as it is wound up has the twofold effect of urging the primary latching lever 22 in a counterclockwise or unlatching direction and the primary detent or pawl in counterclockwise direction, i.e., in a direction toward the latching lever 22.

The spring 51 is similarly structurally and functionally related to the secondary latching lever 23 and its paired detent or pawl 37.

The springs 49 and 51 are designed to urge the latching levers in unlatched direction and the pawls 35 and 37 toward their paired latching levers under normal frictional conditions. This friction is primarily that between the levers and pawls and the pivot shafts on which they are mounted. Latch mechanisms of the type embodying the present invention conventionally are mounted at the front end of the vehicle and are subject to deposits of road dust and mud and also to the corrosive effect of deicing agents used on the road surfaces. It is thus possible for the latch mechanism lubricant to be washed away and for sediment and corrosive byproducts to create increased frictional resistance between the movable latch mechanism parts.

A feature of the present invention is the provision of opposed camming surfaces on the respective pairs of latching levers and detents or pawls. That is, the primary pawl 35 has an upstanding projection or camming portion 56 which lies in the path of the surface 57 on the depending abutment 41 of the primary latching lever 22. The secondary pawl 37 has a camming surface 58 which is adapted to lie in the path of a curved camming surface 59 on the lower edge of the depending abutment 45 of the secondary latching device 23.

The primary and secondary pawls 35 and 37 have a lost motion connection therebetween so that to a degree and under certain conditions movement of either pawl results in corresponding movement of the other pawl. The primary pawl 35 has a flanged pin 61 fixed thereon, the pin 61 having an end portion 62 projecting through an enlarged aperture 63 in the pawl 37.

The detents or pawls 35 and 37 are disengageable from their respective latching levers by actuation of a release lever 64 which is pivotally supported on a pivot stud 65 mounted on a latch lever bracket 66. The bracket 66 is supported in juxtaposition to the housing member 15 by the riveted over ends of the pivot shafts 36 and 38 on which the primary and secondary latch are pivotable (see FIG. 5).

One arm 67 of the lever 64 extends across the latch mechanism to a position in which it is accessible for swinging movement in a clockwise direction as viewed in FIG. 7. The lever 64 has a short actuating arm 68 which extends at substantially right angles to the arm 67. The free end of the arm 68 is adapted to abut the substantially vertical edge 69 of the primary pawl 35. The release lever 64 is spring loaded by a spring 71 encompassing the pivot stud 65 with one end of the spring being anchored in the bracket 66 and the other end being hooked into the lever arm 67.

OPERATION

The operation of the latch assembly 10 embodying the present invention may best be followed with reference to FIGS. 1 and 2 of the drawings. In FIG. 1, the primary latching lever 22 and the secondary latching lever 23 are shown as they would appear when the hinged closure structure, such as the vehicle hood, has been raised to provide access to the vehicle engine compartment. As the closure structure or hood is lowered, the keeper elements 12 and 13 move downwardly over the tapered sidewalls of 18 and 19 of the nose portion 17 of the housing containing the latch mechanism components. The keeper elements 12 and 13 engage the extremities of the lower fingers 26 and 29, respectively, on the latching levers 22 and 23. This results in the latching levers 22 and 23 being rotated in counterdirections, the primary latching lever 22 being rotated in a clockwise direction and the secondary latching lever being rotated in a counterclockwise direction as viewed in FIGS. 2 and 3. The primary pawl 35 and the secondary pawl 37 normally are spring biased toward the latching levers by the springs 49 and 51, respectively. Therefor, as the secondary latching lever 23 continues to rotate in a counterclockwise direction, its depending abutment 45 will ride over the abutment 48 on the secondary pawl 37 until it reaches a point at which the abutment 48 is able to move upwardly to bring the surface 46 on the latching lever abutment 45 and the surface 47 on the pawl abutment 48 into face-to-face contact as shown in FIG. 2. As soon as this occurs, the hood or closure structure is held in what is known as a secondary latched position. That is, it is restrained from movement in an upward or opening direction. In this condition, however, the hood is not in a fully latched condition.

As the secondary latching lever 23 is moving in a counterclockwise direction from the FIG. 1 unlatched position toward the secondary latched position shown in FIG. 2, the primary latching lever 22 also is being moved in a clockwise direction by engagement of the keeper element 12 with its lower finger 26. As the downward movement of the closure structure or hood continues, the abutting faces 46 and 47 on the secondary latching lever abutment 45 and the abutment 48 on the secondary pawl 37 move away from each other. In the event that movement of the latching levers is interrupted before the primary latching lever and the primary pawl become operative to hold the closure structure or hood in latched condition, upward or opening movement of the closure structure or hood under the influence of its counterbalancing springs can occur to the extent required to again bring the abutting surfaces 46 and 47 into engagement with each other. This is possible because the abutment on the secondary pawl 37 remains in the path of the abutment 45 on the secondary latching lever once it is placed in such relationship.

Upon the closure structure or hood being brought to a fully closed position, the abutment 41 on the primary latching lever will move beyond its interference position relative to the abutment 44 on the primary pawl 35. The primary pawl is then able to move upwardly to bring its abutment face 43 into engagement with the abutment face 42 on the abutment 41 of the primary latching lever 22, as shown in FIG. 3. In this condition, the primary latching lever has the main function of holding the closure structure or hood in fully closed or latched condition. The secondary latching lever 23 and its related secondary pawl 37 are always in condition to become engaged to hold the hood or closure structure in proximate latched condition after a slight degree of upward movement occurs should the primary latching lever fail to function.

If, for any reason, springs 49 and 51 do not bias the primary and secondary pawls 35 and 37 respectively toward the latching levers 22 and 23 as the closure structure or hood is brought down into closed position, the opposed camming surfaces on the latching levers and their respective pawls will insure that the pawls are moved into proper latching relationship to the primary and secondary latching levers. Referring again to FIG. 2, in the event that the secondary pawl 37 does not move in a clockwise direction from its unlatched position, a position in which the abutment 48 is below the abutment 47 on the secondary latching lever, the curved surface 58 will lie in abutting relation to the curved surface 59 on the lower edge of the secondary latching lever abutment 45. As the secondary latch 23 moves in a counterclockwise direction, the surfaces 59 and 58 will abut and cause the secondary pawl 37 to be moved in a clockwise direction. This brings the abutment 47 upwardly to the position shown in FIG. 2 in which it lies in opposition to movement of the abutment 45 on the secondary latching lever 23. This prevents the latter from being rotated in a clockwise or unlatching direction. Similarly, if for any reason the primary latching pawl 35 does not move from the position shown in FIG. 2 to its FIG. 3 position upon movement of the abutment 41 on the primary latching lever 22 out of the path of the abutment 44 on the primary pawl 35, the surface 57 of the abutment 41 of the primary latching lever 22 will engage the upstanding arm 56 on the primary pawl 35. This will cause the latter to move in a counterclockwise direction thereby raising the abutment 44 into opposition to the abutment 41 on the primary latching lever 22 so the condition shown in FIG. 3 will be reached. The opposed camming surfaces on the primary and secondary latching levers and their respective primary and secondary pawls thus insure that the pawls always will function to hold their latching levers in latched condition.

Unlatching operation of the latch assembly is through actuation of the release lever 64. Movement of the release lever 64 in a clockwise direction as viewed in FIG. 7 results in the end portion of the lever arm 68 abutting the surface 69 of the primary pawl 35 causing the latter to be moved in a clockwise direction from the position shown in FIG. 3. As soon as the abutment 44 drops out of the path of the primary latching lever abutment 41, the primary latching lever will be urged by the spring 49 toward unlatched position. Movement of the primary pawl 35 is transmitted to the secondary pawl 37 through the pin 61 which rides on the bottom wall of the aperture 63 in the secondary pawl 37. Further movement of the primary pawl 35 beyond the position shown in FIG. 2 by actuation of the lever 64 causes the secondary pawl to be moved in a counterclockwise direction. The abutment 48 on the secondary pawl then drops below the level of the abutment 45 on the secondary latching lever 23 permitting the latter to be freely movable in a clockwise direction. As both the primary and secondary latching levers are restored to the FIG. 1 position, the keeper elements 12 and 13 are able to exit from the bifurcations 28 and 32 of the primary and secondary latching levers so that the closure structure or hood may be lifted to a fully opened position.

It is to be understood that this invention is not limited to the exact construction illustrated and described above but that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

We claim:

1. Latch assembly for releasably latching a hinged closure structure to a vehicle body compartment structure,

the latch assembly comprising a pair of spaced parallel keeper elements on one of the structures and a latch mechanism mounted on the other of the structures,

the latch mechanism comprising a pair of latching levers pivotally mounted on a support member for pivotal movement in counter directions,

each latching lever having keeper element engaging portions projecting substantially radially away from the pivot axis of the respective latching lever for engagement with a respective keeper element,

a pair of detent members each paired with one of the latching members and pivotally mounted on the support,

the detent members each having an abutment engageable with an opposing abutment on its paired latching lever to hold the latter in latched position,

the respective pairs of abutments being rotationally displaced to provide for sequential engagement of first one and then the other of the paired latching levers and detent members as the closure member is moved from an unlatched to a partially latched and then to a fully latched position relative to the vehicle body compartment structure,

spring means biasing the respective latching levers toward unlatched condition and the detent levers toward their paired latching levers,

at least one latching lever and its paired detent member having opposed camming portions lying in abutting relation to each other in unlatched positions of the latching levers,

the opposed camming portions upon movement of the latching levers by and relative to the keeper elements abutting each other to urge the detent member into holding engagement with its paired latching lever in the event the spring means fails to do so following movement of the latching lever to unlatched position to release the closure structure from the body structure,

and release lever means operative to disengage the detent members from the paired latching levers when the closure structure is in latched condition on the body structure.

2. A latch assembly according to claim 1, in which:

the latching levers are pivotal on a common pivot shaft, and

the detent members are pivotal on spaced pivot shafts.

3. A latch assembly according to claim 2, in which:

the support member comprises a housing having a tapered nose portion with openings in opposite sides thereof,

the nose portion being adapted to project between the spaced keeper elements in latched position of the closure structure,

and the keeper element engaging portions projecting outwardly of the nose portion through the openings therein.

4. A latch assembly according to claim 1, in which:

the support member comprises a housing having a tapered nose portion with openings in opposite sides thereof,

the nose portion being adapted to project between the spaced keeper elements in latched position of the closure structure,

and the keeper element engaging portions of the latch mechanism projecting outwardly of the nose portion through the openings therein.

5. A latch assembly for releasably latching a hinged closure structure to a vehicle body compartment structure,

the latch assembly comprising a pair of spaced keeper elements on one of the structures and a latch mechanism mounted on the other of the structures,

the latch mechanism comprising a primary latching lever and a secondary latching lever each pivotally mounted on a common support member for pivotal movement in counter directions,

each latching lever having keeper element engaging portions projecting substantially radially away from the axis about which it pivots,

the keeper element engaging portions being engageable with a respective keeper element,

a primary pawl paired with the primary latching lever and a secondary pawl paired with the secondary latching lever,

the primary pawl and secondary pawl each being pivotally mounted on the same support member as the latching levers,

the detent members each having an abutment engageable with an opposing abutment on its paired latching lever to hold the latter in latched position,

the respective pairs of abutments being rotationally displaced to provide for sequential engagement of first the secondary latching lever by the secondary pawl and then the primary latching lever by the primary pawl as the closure member is moved from an unlatched to a partially latched and then to a fully latched position relative to the vehicle body compartment structure,

spring means biasing the respective latching levers toward unlatched condition and the pawls toward their paired latching levers,

at least one latching lever and its paired pawl having opposed camming portions lying in abutting relation to each other in unlatched positions of the latching levers,

the opposed camming portions upon movement of the latching levers by and relative to the keeper elements abutting each other to urge the pawl into holding engagement with its paired latching lever in the event the spring means is ineffective to do so following movement of the latching lever to unlatched position for release of the closure structure from the body structure,

and release lever means operative to disengage the pawls from the latching levers when the closure structure is in latched condition on the body structure.

6. A latch assembly according to claim 5, in which:

the latching levers are pivotal about a common pivot shaft, and

the pawls are pivoted on spaced pivot shafts.

7. A latch assembly according to claim 6, in which:

the support member comprises a housing having a tapered nose portion with openings in opposite sides thereof,

the nose portion being adapted to project between the spaced keeper elements in latched position of the closure structure,

and the keeper element engaging portions of the primary and secondary latching levers projecting outwardly of the nose portion through the openings therein.

8. A latch assembly according to claim 5, in which:

the support member comprises a housing having a tapered nose portion with openings in opposite sides thereof,

the nose portion being adapted to project between the spaced keeper elements in latched position of the closure structure,

and the keeper element engaging portions of the primary and secondary latching levers projecting outwardly of the nose portions through the openings therein.

9. A latch assembly according to claim 8, in which:

the spring means comprises a spring common to each paired latching lever and pawl.

10. A latch assembly for releasably latching a hinged closure structure to a vehicle body compartment structure,

the latch assembly comprising a latch mechanism mounted on one of the structures coacting with keeper elements on the other of the structures,

the latch mechanism being characterized in that it has a primary latching lever to hold the closure structure in fully closed condition and a secondary latching lever to hold the closure structure in a position proximate to fully closed position,

the primary and secondary latching levers being pivotal in counter directions about a common pivot shaft,

a primary pawl engageable with the primary latching lever and a secondary pawl engageable with the secondary latching lever,

the secondary and primary pawls being engageable sequentially with the respective secondary and primary latching levers, as the closure structure is moved from opened to closed position, to hold the respective latching levers in latched condition,

the primary and secondary pawls being pivotal in counter directions about spaced pivot shafts,

each of the latching levers and the pawl engageable therewith having opposed cam surfaces adapted to abut when the latching lever is moved toward latching position with its respective pawl displaced from latch lever holding position thereby to urge the pawl into latching lever holding position,

the opposed cam surfaces on each pair of latching levers and related pawls being located to abut between the pivot axes of each of the latching levers and related pawls to urge the pawls toward its latching lever,

spring means normally biasing the latching levers toward unlatched condition and the respective pawls toward their latching levers,

release means operative to disengage the pawls from the latching levers to permit movement of the closure structure from closed to opened position,

the primary and secondary pawls having overlapping portions with a lost motion connecting means therebetween so that movement of one pawl will cause movement of the other pawl after predetermined relative movement therebetween,

the latching levers and related pawls being housed within a housing having a tapered nose portion with openings in opposite sides thereof,

the nose portion being adapted to project between the keeper elements in latched position of the closure structure,

the latching levers having keeper element engaging portions projecting outwardly of the nose portion through the openings therein.