Vehicle hood locking mechanism and method for unlocking a vehicle hood

Abstract

Vehicle hood latch (10) comprising: a housing (20), a rotary latch (12) mounted on the housing (20) for pivoting about a first pivot axis (1a), a pawl (14) mounted on the housing (20) for pivoting about a second pivot axis (1b) and biased in engagement with the rotary latch (12), a pin (18) attached to the pawl (14) for common movement with the pawl (14), a double pull lever (17) functionally mounted on the housing (20) for pivoting about a third pivot axis (1c) and having a stop surface (5c) designed for effective engagement with the pin (18), a primary safety catch lever (19) functionally mounted on the housing (20) for pivoting about a fourth pivot axis (1d) and designed toto pivot about the fourth axis (1d) from a locked first position to an unlocked second position depending on a translational movement of the double pull lever (17) caused by the engagement of the pin (18) with the stop surface (5c) of the double pull lever (17), an additional safety catch lever (29) which is functionally mounted on the housing (20) and pivotable about the fourth axis (1d), and a connecting lever (38) which is functionally mounted on the housing (20) and is designed for a pivoting movement about a fifth pivoting axis (1e) depending on a movement of the pin (18), wherein the additional safety catch lever (29) is designed to pivot about the fourth pivoting axis (1d) depending on a pivoting movement of the connecting lever (38).

Description

FIELD OF THE INVENTIONThe present invention relates to latches for vehicle closure flaps and, more particularly, to vehicle hood latches and methods for unlocking vehicle hoods.BACKGROUND OF THE INVENTIONLatches for vehicle hoods and the like are typically operated in two stages. During a first stage, a handle within a vehicle is actuated that moves the latch from a primary closed position to a secondary closed position. To fully release the latch, the vehicle occupant typically has to leave the vehicle and actuate a lever located under the hood. As such, the current state of the art may include a safety catch lever integrated into the hood latch, requiring a vehicle occupant to perform two different operations to unlock the hood, namely pulling the latch from inside the vehicle and moving the safety catch lever from outside the vehicle (i.e., inserting the hand inside the hood area and releasing the hood) to fully release the striker from the latch. This two-stage manual release configuration may be inconvenient in some situations.With respect to raising a hood generally, and particularly for an active pedestrian protection system, the latch is required to provide a movement greater than that required for normal opening. Due to mechanical constraints of springs and targets for mass and packaging, the normal opening thrust for the hood cannot be as great as that provided using an active pedestrian protection system.The automotive industry is attempting to better protect pedestrians from head impacts on vehicles. When a vehicle encounters a pedestrian during a front impact, the pedestrian may spin up and lands on the front hood of the vehicle and / or the windshield. In an effort to reduce the severity of the impact, and particularly to prevent a person's head from impacting the engine block or other hard spot located directly below the hood, it is desirable to actively space the hood from the engine block whenever a front impact is detected.What is desired is a mechanism that provides the following: multi-stage unlocking from within the vehicle, a visual signal that the hood has been unlocked to indicate to a user that the hood is open, a mechanism for accommodating positional tolerances of one or more components of a locking system, and a mechanism for absorbing striker overmove in a closing direction while enabling a normal closing operation, such as during crash situations.DE 10 2009 010 975 A1, KR 10 2003 0041488 A, DE 11 2012 000 578 T5 and DE 10 2012 212 542 A1 each disclose multistage locking systems for vehicle hoods with safety catch mechanisms. DE 10 2009 010 975 A1 discloses a two-stage mechanical locking with a single catch element. KR 10 2003 0041488 A and DE 11 2012 000 578 T5 disclose double catch systems or multiply mounted lever and hook elements, which offer increased safety in the event of damage to the primary catch, and D4 finally relates to an electrically or spring-operated multistage locking system with an additional safety device.SUMMARY OF THE INVENTIONAccording to the invention, a vehicle hood locking system having the features of claim 1 or claim 10 and a method for unlocking a striker having the features of claim 15 are proposed.In accordance with another aspect of the invention, the dual pull lever is pivotally mounted to the primary safety catch lever to facilitate functional cooperation therewith without the incorporation of additional components.In accordance with another aspect of the invention, the third pivot axis and the fourth pivot axis are spaced apart from each other, thereby providing the relative functional movement between the dual pull lever and the safety catch lever.In accordance with another aspect of the invention, the primary safety catch lever may be disposed between the rotary latch and the double pull lever to facilitate operative cooperation between the safety catch lever and the double pull lever.In accordance with another aspect of the invention, a link is coupled to the pawl to disengage the pawl from the ratchet during a first actuation of the link, and wherein the primary safety catch lever is configured to move to the unlocked second position in response to a second actuation of the link, thereby minimizing the number of links required to actuate the latch.In accordance with another aspect of the present invention, the vehicle hood latch includes an additional safety catch lever operatively mounted to the housing to ensure that the hood remains at least partially latched when it is desired to avoid undesired release of the hood to a fully open position.In accordance with another aspect of this invention, the vehicle hood latch may include a biasing mechanism that biases the latch to the unlocked position.In accordance with another aspect of the invention, the method further comprises causing a biasing mechanism to automatically push the hood upward after the depression.In accordance with another aspect of the invention, the method may further include causing the striker to grasp a contact part of the biasing mechanism during depression of the hood to apply a biasing load to the biasing mechanism to facilitate pushing up the hood.BRIEF DESCRIPTION OF THE DRAWINGSThese and other aspects, features and advantages associated with a vehicle hood latch constructed in accordance with the invention will be more readily appreciated when taken into account in the following detailed description of presently preferred embodiments and best mode, appended claims and appended drawings, in which: FIG. 1 is a side view of a vehicle having a latch in accordance with an aspect of the invention, FIG. 2 is an exploded perspective view of the latch of FIG. 1 in accordance with an aspect of the invention, FIG. 3 is a composite perspective view of the latch of FIG. 2, FIG. 4 is an assembled side view of the latch of FIG. 2 shown in a fully latched position, FIG. 5A is an opposite side view to FIG. 4 of the latch of FIG. 2, shown in a fully locked position, FIG. 5B is a view similar to FIG. 5A showing the latch during a first pull operation to place the latch in a first open position, FIG. 5C is a diagram showing the latch at rest in the first open position after the first pulling operation, FIG. 5D is a diagram showing the latch during a second pull to move the latch to a second open position, FIG. 6 is an exploded perspective view of the latch of FIG. 1 in accordance with another aspect of the invention, FIG. 7A is a diagram showing the latch of FIG. 6 at rest in a first open position after a first pulling action, FIG. 7B is a diagram illustrating the latch of FIG. 6 during a second pull operation to move the latch to a second open position, FIG. 7C is a diagram showing the lock of FIG. 6 upon release of an operation link after the second pulling operation, FIG. 7D is a diagram showing the latch of FIG. 6 in a fully open position after depressing a hood of the vehicle to cause the latch to move to its fully open position, FIG. 7E is a fragmentary rear view of the latch while in the position of FIG. 7B, showing a link lever cooperating with a pin attached to a second safety catch, FIG. 7F is a similar illustration to FIG. 7E of the latch being in the position of FIG. 7C showing the link lever spaced from the pin attached to the second safety catch, FIG. 7G is a similar illustration of the latch as shown in FIG. 7F, while in the position of FIG. 7D, showing the pin connected to the second safety catch received in a slot of the link lever, FIG. 8 shows an example striker biasing mechanism of the latch of FIG. 1 in accordance with another aspect of the invention, FIG. 9A shows the striker biasing mechanism of FIG. 8 in a fully open position corresponding to the locking positions of FIGS. 5D and 7D , FIG. 9B shows the striker biasing mechanism of FIG. 8 in the fully closed position corresponding to the locking position of FIG. 5A , FIG. 9C shows the striker biasing mechanism of FIG. 8 in an over-travel position corresponding to an impact of an object on the vehicle hood, FIGS. 10A and 10B are perspective views of a striker biasing mechanism in accordance with another aspect of the invention, FIG. 11A shows a side view of a latch without an overflow receiving feature; and FIGS. 11B and 11C show opposing side views of a latch having an overflow receiving feature.DETAILED DESCRIPTION OF THE INVENTIONReferring now to the drawings in further detail, Figure 1 shows a vehicle 11 having a vehicle hood latch, referred to hereinafter as latch 10, constructed in accordance with the invention. The latch is operable to lock a hood 13 of the vehicle in various conditions including a primary closed position, also referred to as a fully closed position, a first open position, also referred to as a secondary closed position, a partially closed position, or an intermediate closed position, a second open position, also referred to as a fully unlocked position, and in some cases, a tertiary open position, which is a partially open position between the first and second open positions, the latch and its associated positions being discussed in further detail later. The latch 10 is configured to engage a striker 22 attached to the hood 13 to selectively maintain the latch and hood in one of the fully closed or partially open positions, while also being configured to selectively release the striker 22 to allow the hood to be fully opened. The latch may be configured for movement between the various positions without having to manually touch the latch 10, for example, via a number of actuations of an actuation link 21 operatively connected to the latch. Further, the latch 10 may be configured for movement to the fully open position from a partially open position by depressing the hood 13, thereby avoiding a component of the latch from having to be gripped to fully disengage the hood 13 from the latched engagement with the latch 10.Referring to FIGS. 2-4, according to one aspect of the invention, the hood latch 10 includes a housing 20 for operatively mounting to the vehicle 11, a ratchet 12 formed on the housing 20 for pivoting about a first pivot axis 1 aand biased from engagement with the striker 22 by a ratchet biasing member such as a spring member 13 a, a pawl 14 mounted on the housing 20 via a pin member for pivoting about a second pivot axis 1 bof the pin member and biased into engagement with the ratchet 12 by a biasing member such as a spring member 13 b, a connection lever also referred to as a release lever or double pull lever 17, The safety catch is operatively mounted to the housing 20 and is operatively mounted to the pawl 14 via a pin 18 for pivoting about a third pivot axis 1c in response to movement of the pin 18 to cooperate with a primary safety catch member also referred to as a safety catch lever or safety catch member 19, the safety catch member 19 being mounted to the housing 20 via a pin (i.e. rivet) 16 for pivoting about a fourth pivot axis 1d and being biased into engagement with the striker 20 via a biasing member such as a spring member 13d. The safety catch member 19 has a hook profile tab defining a surface 25 for engaging the striker 22 to maintain the latch in a less than fully open position whereby the striker 22 is held against disengagement from the latch 10 within or otherwise adjacent a fish mouth shaped slot 23 in the ratchet 12 until further selective intended actuation of the double pull lever 17 causes the safety catch member 19 to be disengaged from the blocking of the escape of the striker 22 from the latch 10. As will be discussed further below, movement of the striker 22 out of the latch 10 may be facilitated by a biasing mechanism 50 (FIG. 8 ) disposed between a body component 9 of the vehicle 11 and the hood 13 and shown operatively attached to the body component 9. Movement of the biasing mechanism 50 from a loaded position (FIG. 9B ) to an unloaded position (FIG. 9A ) occurs automatically when the striker 22 is released from the closed or locked position of the latch 10 to the fully open position (i.e., the first open position to the second open position), as discussed below).The double pull lever 17 is biased into engagement with the striker 22 via a biasing member such as a spring member 13c. The double pull lever 17 is pivotally mounted to the safety catch member 19 via a pin 27, the safety catch member 19 being shown as extending between the double pull lever 17 and the pawl 14, the double pull lever 17 and the safety catch member 19 being parallel or substantially parallel to each other. The double pull lever 17 is in operative contact via a stop surface groove 5c with an engagement surface 4b of the pin 18 which is firmly connected to the pawl 14. As such, pivotal movement of the pawl 14 about the pivot axis 1b (by actuation via the link 21) causes translational movement of the pin 18 through a slight arc within an elongate curved slot 31 in the housing 20, thereby causing displacement and pivotal movement of the double pull lever 17 about the pivot axis 1c (counterclockwise in the view of Figure 5B), which, on the other hand, causes further pivotal rotation of the safety catch member 19 about the pivot axis 1d, since the double pull lever 17 is connected to the safety catch member 19 via the pin 27 attached to the safety catch member 19. It is to be appreciated that the connection between the double pull lever 17 and the safety catch member 19 may be a rotational engagement so that the relative angular position between the double pull lever 17 and the safety catch member 19 may change when the movement of the pawl 14 about the pivot axis 1 bis performed by the influence of the connection 21. Accordingly, the double pull lever 17 is engaged by the pin 18 of the pawl 14 during actuation of the latch 10 during a first actuation (i.e., pulling) of the link 21, causing release of the striker from the ratchet 12, see further below.Referring to FIGS. 2-4, components of the latch 10 include the ratchet 12 and its pivot axis 1 a, the striker 22, and the slot also referred to as its retainer portion 23, the ratchet and a closing groove 3 athereof for coupling with a curved protrusion also referred to as retainer portion 2 bof the pawl 14 (FIG. 4 ), and the release spring 13 afor biasing the ratchet 12 to a released position (allowing the striker 20 to release from the retainer portion 23 and automatically rotate the ratchet 12 about the pivot axis 1 aunder the bias of the spring member 13 a). Other components of the latch 10 include the pawl 14 and pivot axis 1 band the ratchet holding portion 2 bthereof for coupling with the ratchet 12, the double pull contact profile, also referred to as extension or surface 4 bof the pin 18 for operatively coupling the pawl 14 to the double pull lever 17, a mounting flange or feature 5 bof the pawl 14 for facilitating the connection of the pawl 14 to the connection 21 (i.e., a cable and a handle 5 disposed within the passenger compartment of the vehicle 11 for easily allowing an occupant to actuate the connection 21, for example, by pulling the handle), and the release spring element 13 bfor biasing the pawl 14 to a closed position and in contact with the ratchet 12, for example, This is to bring the holding portion 2b of the pawl 14 into engagement with the closing groove 3a of the rotary latch 12. As such, rotation of the pawl 14 about the axis 1b causes the ratchet holding portion 2b to be disengaged from the locking groove 3a, thereby causing the automatic rotation of the ratchet 12 about the pivot axis 1a.Referring to FIGS. 5A-5D, various stages of the operation of the latch 10 are illustrated. In stage 1 (Fig. 5A), when latch 10 is in a closed / locked position, double pull lever 17 is biased into engagement with striker 22, and as such, stop surface 4b of pin 18 is disengaged and spaced from groove / stop surface 5c of double pull lever 17. in this orientation between pin 18 and groove 5c of double pull lever 17, actuation of pawl 14 will affect the positioning of ratchet 12 without affecting the position of safety catch lever 19 because initial actuation of pawl 14 is provided while groove 5c and surface 4b are maintained disengaged from each other when pawl 14 is rotated under the influence of link 21. Upon initial release of the rotary latch 12 from the pawl 14, the latch 10 moves from the fully closed position to the primary open position, also referred to as the first open position, as it passes from the step 1 to the step 2.In stage 2 (Figure 5B), when latch 10 is disposed in the first open position, link 21 has been actuated a first time, as by pulling handle 5 within the vehicle, causing pawl 14 to rotate about arrow 10a and surfaces 2b, 3a to disengage, to allow automatic counterclockwise rotation of ratchet 12 under the bias of spring member 13a, as shown by arrow 10c, and thus movement of striker 22 along line 10c to enter slot 23. It should also be noted in step 2 that a movement of the striker 22 away from the double pull lever 17 due to the movement of the rotary latch 12 allows rotation of the double pull lever 17 about the pivot axis 1 cin the direction of the arrow 10 d, and thus places the stop surface 24 of the double pull lever 17 in contact with the surface 4 bof the pin 18. It should be noted that the groove / surface 5c of the double pull lever 17 is disengaged from the surface 4b when the surface 4b is engaged with the abutment surface 24 of the double pull lever 17. It is further to be appreciated that surface 4b is free to move along surface 24 when both are engaged. Latch 10 remains in the primary open position as it moves from stage 2 to stage 3.In stage 3 (FIG. 5C ), the link 21 is released by a first operating pull, and the pawl 14 rotates along the direction of arrow 10 eand is allowed to return to a rest position. The movement of the pawl 14 also allows the surfaces 4b and 24 to be disengaged from each other, whereby the surface 4b is moved into engagement with the groove / abutment surface 5c and a rotation of the double pull lever 17 along the arrow 10f is made possible under the tension of the spring element 13c. For step 3, it will be noted that pin 18 is received within groove 5c, thereby causing co-movement of double pull lever 17 with pawl 14 during a subsequent pulling operation of link 21, thereby causing latch 10 to move to a secondary open position as it moves from step 3 to step 4.In step 4 (Fig. 5D), the link 21 is actuated a following (second) time (i.e. after the first pull and release of the handle 5, the handle 5 is pulled a second time by the user), whereby the pawl 14 is rotated along the direction of the arrow 10g and causes engagement of the pin 18 and the groove surface 5c, whereby a translation movement (a translation movement is to be understood as being over a path other than a purely rotation, for example purely linear or a curvilinear path) of the double pull lever 17 and causes a joint rotation of the safety catch element 19 along the direction of the arrow 10h away from the entrance of the slot 23, whereby the surface 25 is moved out of contact with the striker 22 and thus the striker 22 is released from being held by the safety catch 19. Accordingly, movement of the linkage 21 causes rotation of both the safety catch lever 19 about the pivot axis 1d from a first locked position (engaging the striker 22) to a second unlocked position (disengaged from the striker 22) and pivotal movement (shown as purely pivotal) of the double pull lever 17 (spaced from the pivot axis 1d) about the pivot axis 1d, it being noted that "about" describes rotation coupled to the axis 1b and "about" describes displaced rotation spaced from the axis 1b. It should be noted that the release of the striker 22 from the catching engagement by the safety catch element 19 can also lead to a further rotation of the rotary latch 12 about the pivot axis 1 c.As such, the above structure of the hood latch 10 can facilitate opening from inside the vehicle 11 with a double operation (i.e., pulling) of the double pull lever 17 while also providing a safety catch function via the safety catch member 19 integrated in the housing 20 of the latch 10.Referring to Fig. 6, there is shown an alternative embodiment of the latch 10 in accordance with another aspect of the invention having an additional or supplemental safety catch member or lever 29 which can rotate independently of the rotation of the first safety catch member 19. The purpose and function of the second safety catch 29 is to provide engagement of the striker 22 with a hook 30 (i.e., stop) of the safety catch 19 in the event that a dual actuation release of the latch 10 has occurred (as explained with reference to FIGS. 5A-5D ) and the vehicle 11 is subsequently driven by the user while the striker is in the step 4 (i.e., in the fully unlocked open position and thus can move freely up and away from the slot 23). Undesired operation of the vehicle 11 during the open position of the latch may occur when, for example, a hood ajar signal or hood open signal is ignored (or otherwise faulted) by the user when the engine is started and the transmission is shifted. To accommodate undesired vehicle operation while the latch 10 is in the open position, the additional safety catch 29 interferes and grasps the striker 22 after the second actuation of the linkage 21. In conjunction with the additional safety catch 29, after the dual actuation release, the user may perform an operation to intentionally release the additional safety catch 29 (i.e., walk to the front of the vehicle 11, gently depress the hood 13, and cause the safety catch 29 to disengage from the striker 22). In this embodiment, step 4 of FIG. 5D corresponds to the first open (although still in a second open position, as latch 10 was subjected to two actuations of linkage 21 from within the vehicle), with latch 10 remaining in a partially open and less than fully closed position, thereby still being in a partially locked state. Then, upon subsequent, third or tertiary actuation, the latch is moved to a fully open tertiary open position via release of the striker 22 from the additional safety catch 29.Referring again to FIG. 6, the additional safety catch 29 may be referred to as a mechanical hood 13 engagement latch 10 component. The additional safety lever 29 can be mounted for a coaxial pivoting movement with the safety catch lever 19. The second safety lever 29 is positioned for a pure rotation about the pivot axis 1d (i.e. the same pivot axis of the safety lever 19). The rotation of the second safety lever 29 is biased away from engagement with the striker 22 to a release position by a biasing member such as a spring member 13 emounted on the housing 20 and a tab 32 of the second safety lever 29. A stop 34 (i.e., a pin) is connected to the second safety lever 29, the pin 34 being configured to be received in a slot 36 of a connecting lever 38 to facilitate movement of the second safety catch 29 to an unlocked position. It should be noted that the spring member 13e biases the stop 34 toward the slot 36 to facilitate movement of the additional safety catch 29 to the unlocked position. The connecting lever 38 is operatively connected to the housing 20 via a pin 40 so as to allow the connecting lever 38 to rotate about a fifth pivot axis 1 e. As such, the positioning of the link lever 38 (i.e., during the first open stage) locks the second safety lever 29 against rotation when the link 21 is activated. The link 38 is operatively coupled to the pawl 14 via receipt of the pin 18 in a slot 42 in the link 38. As the pawl 14 pivots, the pin 18 causes a simultaneous pivoting movement of the connecting lever 38 about the pivot axis 1e by a displacement along the slot 42. Thus, the rotational position of the connecting lever 38 is directly influenced by the position of the pin 18 in the slot 42 and the position of the pin 18 in the slot 42 is directly influenced by the pivoting movement of the pawl 14 about the pivot axis 1b.Referring to FIG. 7A, latch 10 is in a step 1a similar to step 3 of FIG. 5C. As such, the striker 22 is engaged by the safety catch 19, and the second safety catch 29 may rest without engaging the striker 22, although it is in a position overlying the striker 22. In a step 2a (Fig. 7B) similar to the step 4 of Fig. 5D, the double pull lever 17 is operated once by the second operation of the link 21 from inside the vehicle 11 via the handle 5, and thus the safety catch lever 19 is moved in the direction of the arrow 10h out of engagement with the striker 22, and thus the striker 22 is free to engage with the overlying second safety catch member 29. As explained above, the rotary latch 12 is free to rotate in the direction of arrow 10i to release the striker 22 from the receiving portion 23. As shown, the position of the link lever 38 via rotation in the direction of arrow 10j (under the influence of the position of the pin 18 in the slot 42) engages the pin 34 on the second safety catch 29 through the stop surface 46 (FIG. 7E ) of the link lever 38 adjacent the slot 40, thereby preventing rotation of the second safety catch 29 away from the overlying relationship and abutting the striker 22, thereby maintaining the second safety catch 29 in a locked position. The step 2 a(FIG. 7B ) may be referred to as the first open position of the latch 10 as the striker 22 is free of the first safety catch 19 but is still blocked by the additional safety catch 29. A transition from the step 2 ato the step 3 a(FIG. 7C ) is performed when the link 21 is released by the user, thereby allowing the pawl 14 to return to the rest position under the influence of the biasing member 13 b. This pivoting of the pawl 14 causes the pin 18 to move in the slot 42 and thus to rotate the link lever 38 about the pivot axis 1e in the direction of the arrow 10k. Accordingly, the link lever 38 pivots about the fifth pivot axis. This rotation in the direction of arrow 10k positions stop surface 46 out of engagement with pin 34, thereby permitting movement of second safety catch lever 29 away from overlying relationship with striker 22 under the influence of biasing member 13e when striker 22 is moved out of engagement with stop surface 30 of additional safety catch member 29.As it moves from the step 3 ato the step 4 a(FIG. 7D ), the hood 13 is moved downward along the direction 10L by the user against the bias of the hood biasing mechanism 50 (FIG. 8 ). Once the position of the striker 22 is such that it exits the striker receiving region formed by the stop surface 30, the second safety catch member 29 rotates along the direction of arrow 10M away from the striker 22 and out of overlying relationship therewith under the influence of the biasing member 13 e, thereby placing the latch in a second (or tertiary, as mentioned above) open position to allow subsequent movement of the striker 22 out of the latch 10 in a direction opposite the arrow 10 h. Furthermore, it should be mentioned for the step 4a that the pin 34 is positioned in the slot 36 due to the rotation of the second safety catch 29 in the direction of the arrow 10m, whereby a joint rotation of the second safety catch 29 with the first safety catch 19 is established upon a subsequent closing of the latch 10, i.e. a return to the closed position of the step 1 of the latch 10 of Fig. 5A, and wherein the second safety catch 29 is in a position similar to its position in the step 1a (Fig. 7A).Referring to Fig. 8, there is shown an embodiment of the biasing mechanism 50. As discussed above, relief of the biasing mechanism 50 occurs when the striker 22 moves from the closed or locked position of the latch 10 to the open position (i.e., from the first open position to the second open position, as discussed above). In contrast, loading of the biasing mechanism 50 occurs when the striker 22 moves from the open position to the closed or locked position of the latch 10 (i.e., from the second open position to the first open position, as discussed above). The biasing mechanism 50 may include a housing portion 52 of the housing 20 for mounting the biasing mechanism 50 as part of the entire latch 10, a contact portion 54 for abutting the bottom of the hood 13, an elastic biasing member 56 (i.e., a spring member shown as a coil spring) for providing the biasing of the striker 22 to the open position of the latch 10, and a back plate 58 for securing the biasing mechanism 50 within the housing. As such, the cooperation, indicated by 59, between the stop member 54 and the hood 13 during depression of the hood 13 provides a degree of compression of the resilient member 56 based on the positioning of the striker 22 relative to the slot 23 of the latch 10. It should be noted that between the positions shown in Figs. 9A and 9B, the position and state of compression are the elastic member 56 exerting the load responsible for pushing the hood 13 upward.Referring to FIGS. 10A-10B, an alternative embodiment of the latch 10 is shown wherein the biasing mechanism 50 of FIG. 9 is replaced with a striker biasing member, shown by way of example and without limitation as a coil spring 52, connected at one end to a biasing lever 54 and at the other end to a portion of the housing 20. In the closed position of the latch 10, the striker 22 is forced to abut against the biasing lever 54 and thus exerts and places the biasing member 52 under a biased spring load. In contrast, movement of the safety catch 19, 29 from the obstruction of the striker 22 allows the striker 22 to move toward the mouth of the slot 23 to an open position, thus allowing the biasing member 52 to relieve and release the biasing force on the striker 22, which tends to urge the striker 22 upward to the open position.Referring to Figures 11A-11C, there are shown various versions of the latch 10 with and without receiving overflow of the striker 22 in the slot 23 when the latch 10 is in the closed position. For example, as shown in FIG. 11A, a rivet 58 attached to the housing 20 may be used to block or otherwise prevent over-travel of the striker 22 by blocking counterclockwise rotation of the ratchet 12 via a stop surface 60. In the overflow case, as illustrated in FIG. 12C, the lever 17 may be configured to accommodate overflow of the striker 22 using the (or in addition to) biasing member 13 c.In accordance with another aspect of the invention, a method of unlocking a vehicle hood 13 is provided. The method provides a reliable, secure manner in which the vehicle hood 13 can be easily and quickly unlocked without accidentally unlocking the hood 13, unless desired, to a fully unlocked state. Accordingly, unintentional opening of the hood 13 is prevented, whereby unpredictable damage to the vehicle 11 can be avoided. The method includes unlocking a striker 22 of the hood 13 of the vehicle 11 from a vehicle hood latch 10. the method further includes operating a linkage 21 of a system of the vehicle hood latch 10 in a first operation from within the passenger compartment of the vehicle 11 to place the vehicle hood latch 10 in a first open position that is less than fully unlocked. Further, the method includes actuating the linkage 21 in a second actuation subsequent to the first actuation from within the cabin of the vehicle 11 to bring the vehicle hood latch 10 to a second open position that is less than fully unlocked. Further, the method includes depressing the hood 13 to cause the vehicle hood latch 10 to move to a fully unlocked position, thereby allowing the hood 13 to be fully opened as intended. In accordance with another aspect of the method of unlocking and opening the vehicle hood, the method may further include causing a biasing mechanism 50 to automatically push the hood 13 upward after the hood 13 is depressed. Further, the method may further include causing the striker to engage a contact part 54 of the biasing mechanism 50 while the hood 13 is depressed to apply a biasing load to the biasing mechanism 50 to facilitate pushing up the hood 13. Of course, further steps are contemplated herein which will be readily appreciated by those skilled in the art in view of the present invention. In the following description, details are set forth to provide an understanding of the present invention. In some instances, certain circuits, structures, and techniques are not described or illustrated in detail in order not to obscure the invention.The terminology used herein is used for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" may intend to include the plural forms as well, unless the context indicates otherwise. The terms "comprise," "comprising," "include," and "with" are inclusive and thus indicate the presence of stated features, points, steps, operations, elements, and / or components, but do not indicate the presence or addition of one or more features, points, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be considered as necessarily requiring their execution in the particular order discussed or illustrated, unless indicated as an order of executions. It should also be understood that additional or alternative steps may be employed.When an element or feature is referred to as being "on," "engaged to," "connected to," or "coupled to," "operatively connected to," or "in operative communication with" another element or feature, it may be directly on, engaged to, connected to, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to" another element or feature, there are no intervening elements or layers to be present. Other words for describing the relationships between elements are to be interpreted in the same manner (i.e., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.Although the terms first, second, third, etc. may be used herein to refer to various elements, components, regions, directions, and / or axes, these elements, components, regions, directions, and / or axes are not intended to be limiting by these terms. These terms may be used only to distinguish one element, component, region, direction, or axis from another region, direction, or axis. Terms such as "first," "second," and other numerical terms used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, range, direction, or axis described later may be referred to as a second element, component, range, direction, or axis without departing from the teachings of the embodiments.Spatially relative terms such as "inner," "outer," "below," "bottom," "lower," "above," "above," and the like may be used herein to simplify the description to describe the relationship of one element or feature to another element(s) or feature(s) depicted in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientations shown in the figures. For example, if a figure is turned over, elements referred to as "below" or "below" other elements or features are then oriented "above" the other elements or features. Thus, the example of the term "below" may include both an orientation above and below. The device may be otherwise oriented (rotated degrees or other orientations) and the spatially relative descriptions used herein are to be interpreted accordingly.

Claims

A vehicle hood latch (10) comprising: a housing (20); a ratchet (12) mounted to the housing (20) for pivotal movement about a first pivot axis (1a); a pawl (14) mounted to the housing (20) for pivotal movement about a second pivot axis (1b) and biased into engagement with the ratchet (12); a pin (18) mounted to the pawl (14) for movement in unison with the pawl (14); a dual pull lever (17) operatively mounted to the housing (20) for pivotal movement about a third pivot axis (1c) and having a stop surface (5c) configured for operative engagement with the pin (18); a primary safety catch lever (19), said safety catch lever being operatively mounted on said housing (20) for pivoting about a fourth pivot axis (1d) and being adapted to pivot about said fourth axis (1d) from a locked first position to an unlocked second position in dependence on a translatory movement of said double pull lever (17) caused by engagement of said pin (18) with said abutment surface (5c) of said double pull lever (17), an additional safety catch lever (29) operatively mounted on said housing (20) and pivotable about said fourth axis (1d), and a connecting lever (38) operatively mounted on said housing (20) and being adapted to pivot about a fifth pivot axis (1e) in dependence on a movement of said pin (18), said additional safety catch lever (29) being adapted to be actuated, about the fourth pivot axis (1d) in dependence on a pivoting movement of the connecting lever (38).The vehicle hood latch (10) of claim 1, wherein the double pull lever (17) is pivotally mounted to the safety catch lever (19).The vehicle hood latch (10) of claim 2, wherein the third pivot axis (1c) and the fourth pivot axis (1d) are spaced apart from each other.The vehicle hood latch (10) of claim 1, wherein the primary safety catch lever (19) is disposed between the rotary latch (12) and the double pull lever (17).The vehicle hood latch (10) of claim 1, further comprising a link (21) connected to the pawl (14) for releasing the pawl (14) from the ratchet (12) during a first actuation of the link (21).The vehicle hood latch (10) of claim 5, wherein the primary safety catch lever (19) is configured to move to the unlocked second position in response to a second actuation of the linkage (21).The vehicle hood latch (10) of claim 1, wherein the connecting lever (38) has a slot (42) and the pin (18) is received for sliding movement along the slot (42).The vehicle hood latch (10) of claim 1, wherein the linkage lever (38) includes a slot (36) adjacent the one stop surface (46) of the linkage lever (38), the slot (36) being configured to receive a stop (34) of the additional safety catch lever (29) to facilitate pivotal movement of the additional safety catch lever (29) to an unlocked position.The vehicle hood latch (10) of claim 1, further comprising a biasing mechanism (50) that biases the vehicle hood latch (10) to the unlocked position.A vehicle hood latch (10) comprising: a housing (20); a ratchet (12) mounted to the housing (20) for pivotal movement; a pawl (14) mounted to the housing (20) for pivotal movement in biased engagement with the ratchet (12); a first safety catch lever (19) operatively mounted to the housing (20) for pivotal movement between a locked position relative to a striker (22) attached to a vehicle hood (13) and an unlocked position relative to the striker (22); a second safety catch lever (29) mounted to the housing (20) for pivotal movement between a locked position relative to the striker (22) and an unlocked position relative to the striker (22), wherein the second safety catch lever (29) is pivotable independently of the first safety catch lever (19), and a pin (18) fixed for movement in common with the pawl (14), and a double pull lever (17) operatively mounted to the housing (20) for pivoting movement, the double pull lever (17) being configured for operative engagement with the pin (18), the first safety catch lever (19) pivoting from its locked position to the unlocked position in dependence on a translation movement of the double pull lever (17) caused by engagement of the pin (18) with the double pull lever (17).The vehicle hood latch (10) of claim 10, wherein the first and second safety catch levers (19, 29) pivot about the same axis.The vehicle hood latch (10) of claim 10, further comprising a link lever (38) operatively mounted to the housing (20), the link lever (38) being configured for pivotal movement in response to movement of the pin (18), the second safety catch lever (29) being configured to pivot in response to pivotal movement of the link lever (38) to the unlocked position.The vehicle hood latch (10) of claim 12, wherein the link lever (38) has a first slot (42) and the pin (18) is received for sliding movement along the first slot (42) and wherein the second safety catch lever (29) has a stop (34) and the link lever (38) has a stop surface (46) configured to confront the stop (34) of the second safety catch lever (29) to maintain the second safety catch lever (29) in the locked position.The vehicle hood latch (10) of claim 13, wherein the connecting lever (38) includes a second slot (36) adjacent the stop surface (46), the second slot (36) being configured to receive the stop (34) of the additional safety catch lever (29) to facilitate pivotal movement of the additional safety catch lever (29) to an unlocked position.A method of unlocking a hood (13) of a vehicle (11) from a vehicle hood latch (10), comprising: actuating a connection of the vehicle hood latch (10) in a first actuation from within a passenger compartment of the vehicle (11) to bring the vehicle hood latch (10) into a first open position that is less than fully unlocked; actuating the connection of the vehicle hood latch (10) in a second actuation subsequent to the first actuation from within the passenger compartment of the vehicle (11) to bring the vehicle hood latch (10) into a second open position that is less than fully unlocked; and depressing the hood (13) to cause the vehicle hood latch (10) to move into a fully unlocked position.The method of claim 15, further comprising causing a biasing mechanism (50) to automatically push the hood (13) upward after the depressing.

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