Vehicle door latch apparatus

A vehicle door latch apparatus has a latch that is engaged with a striker; a ratchet member rotatably supported by a ratchet shaft and that has a pawl portion, wherein the pawl portion is movable between a latch engaging position, where the pawl portion can face a full latch engaging portion of the latch, and a latch releasing position, where the pawl portion is not in contact with the full latch engaging portion, wherein release component force is generated in a latch releasing direction when latch return force is applied in a releasing direction at the latch engaging position, and the ratchet member is pushed out from the latch engaging position to the latch releasing position by the release component force; a ratchet restraint that is arranged on a side of the ratchet member and that can be moved about a pin between a block position and a release position.

TECHNICAL FIELD

This application claims priority from Japanese Patent Application No. 2017-248491 filed on Dec. 25, 2017. The application is incorporated herein by reference in its entirety.

The present invention relates to a vehicle door latch apparatus. In particular, the present invention relates to a vehicle door latch apparatus that reduces release operation force that is required to disengage a ratchet from a latch.

BACKGROUND ART

In a typical prior art vehicle door latch apparatus, a ratchet engages a latch that has rotated from an unlatched position to a full-latched position, and thereby prevents the latch from rotating in a releasing direction in order to keep the vehicle door closed (in the full-latched state). Further, in the vehicle door latch apparatus, the ratchet is rotated in the latch releasing direction (a direction opposite to the latch engaging direction), by a manual release operation force from a door opening handle or by an electric release operation force from a power release mechanism, to disengage the ratchet from the latch, and thereby allows the latch to rotate in the releasing direction to make the vehicle door openable.

The latch is strongly pressed against the ratchet in the full-latched state by being strongly biased in the releasing direction by the resilient force of a latch spring and by the repulsive force of a seal member that is provided between the door and the vehicle body. The ratchet is also biased in the latch engaging direction by the resilient force of a ratchet spring. The friction force, which is generated by the latch being pressed against ratchet, and the elasticity of the ratchet spring act as resistive force against the release operation force, resulting in degradation of the operation feeling when operating the door opening handle and in an increase in the size of the power release mechanism.

Patent Document 1 discloses a vehicle door latch apparatus that reduces the release operation force for releasing a ratchet from a latch.FIG.13shows the mechanism for reducing the release operation force in Patent Document 1. Latch A is held in the full-latched position by engagement with ratchet B, and ratchet B is prevented from rotating in the latch releasing direction by abutting against ratchet restraint C that is provided on the side of ratchet B. In the full-latched state shown inFIG.13, the pressure that is transmitted from latch A to ratchet B is largely supported by ratchet shaft D of ratchet B, but part of the pressure acts on ratchet B as release component force E that rotates ratchet B in the latch releasing direction.

Release component force E is set to be higher than the engagement keeping force that keeps ratchet B engaged with latch A, specifically, the sum of the friction force that is generated between latch A and ratchet B and the resilient force of the ratchet spring that biases ratchet B in the latch engaging direction. Therefore, when ratchet restraint C is rotated clockwise by the manual release operation force or by the electric release operation force in order to disengage ratchet restraint C from ratchet B, ratchet B is rotated in the latch releasing direction by release component force E and is pushed out from the latch engaging position to a latch disengaging position. As a result, ratchet B is disengaged from latch A, and the door is made openable.

In the configuration disclosed in Patent Document 1, the friction force that is generated between ratchet restraint C and ratchet B acts as force that is resistive against the release operation force. However, the resistive force is considerably reduced as compared to the force that is resistive against the release operation force in a conventional apparatus, that is, the friction force that is generated by the latch pressing the ratchet and the resistive force that arises from the elasticity of the ratchet spring, and accordingly, the release operation force can be reduced considerably.

PRIOR ART DOCUMENT

Patent Document

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

In the configuration ofFIG.13, ratchet B cannot rotate in the latch releasing direction unless ratchet restraint C is rotated clockwise by the manual release operation force or by the electric release operation force in order to disengage ratchet restraint C from ratchet B. Due to this structural limitation, latch A can only be provided with one engaging portion F that engages ratchet B.

Here, suppose that another engaging portion, specifically, a half latch engaging portion is arranged together with engaging portion F. Per this assumption, when ratchet B engages the half latch engaging portion, ratchet B, which is held by ratchet restraint C such that it cannot be disengaged from the latch, is mechanically locked by the half latch engaging portion. Therefore, the mechanically locked state of ratchet B cannot be released by a normal operation, and it is necessary to rotate ratchet restraint C by the manual release operation force or by the electric release operation force. This makes it difficult to use a typical latch that has a half latch engaging portion and a full latch engaging portion that are arranged on the outer circumference thereof.

Means for Solving the Problem

A vehicle door latch apparatus according to a first aspect of the invention comprises:

a latch that is engaged with a striker and that is rotatable from an unlatched position to a full-latched over rotating position;

a ratchet member that is rotatably supported by a ratchet shaft and that has a pawl portion, wherein the pawl portion is movable between a latch engaging position, where the pawl portion can face a half latch engaging portion of the latch, and a latch releasing position, where the pawl portion is not in contact with the half latch engaging portion, wherein release component force is generated in a latch releasing direction when latch return force is applied in a releasing direction at the latch engaging position, and the ratchet member is pushed out from the latch engaging position to the latch releasing position by the release component force;

a ratchet restraint that is arranged on a side of the ratchet member and that can be moved about a pin between a block position and a release position, wherein at the block position, the ratchet restraint abuts against the ratchet member to prevent the ratchet member from moving from a latch engaging position, where the ratchet member engages the latch due to the release component force, to a latch disengaging position, and at the release position, the ratchet restraint is detached from the latch member to allow the latch member to move from the latch engaging position to the latch disengaging position,

the ratchet restraint has a pole lever, wherein the pole lever can be disengaged from the full latch engaging portion by rotating about a connecting shaft in a latch disengaging direction when the ratchet restraint is at the block position, and

the ratchet member has a base lever that is rotatably supported by a ratchet shaft, and the pole lever is rotatably supported on the base lever by the connecting shaft.

According to the vehicle door latch apparatus of the second aspect of the invention, in the invention of the vehicle door latch apparatus of the first aspect, the latch has a full latch engaging portion that is arranged together with the half latch engaging portion.

According to the vehicle door latch apparatus of the third aspect of the invention, in the invention of the vehicle door latch apparatus of the first or second aspect, the ratchet restraint has a blocking surface, which is an arc surface whose center is positioned at the pin, and an inclined cam surface that extends contiguous with the blocking surface and whose radius from the pin gradually decreases.

According to the vehicle door latch apparatus of the fourth aspect of the invention, in the invention of the vehicle door latch apparatus of the third aspect, the pole lever is pressed against the base lever in a latch engaging direction by resilient force of a ratchet spring, a coil portion of the ratchet spring is supported by the connecting shaft, one of spring legs of the ratchet spring is engaged with ratchet shaft, and the other is engaged with the pole lever.

According to the vehicle door latch apparatus of the fifth aspect of the invention, in the invention of the vehicle door latch apparatus of the third aspect, the base lever can be rotated from a restricted position, where the base lever is in contact with the blocking surface, to a non-restricted position by the releasing component force.

According to the vehicle door latch apparatus of the sixth aspect of the invention, in the invention of the vehicle door latch apparatus of the fifth aspect, the ratchet restraint includes a cam biasing spring that biases the ratchet restraint from the release position toward the block position.

According to the vehicle door latch apparatus of the seventh aspect of the invention, in the invention of the vehicle door latch apparatus of the third aspect, the inclined cam surface of the ratchet restraint returns the base lever from the unrestricted position to the restricted position when the ratchet restraint is returned to the block position from the release position by resilient force of the cam biasing spring.

According to the vehicle door latch apparatus of the eighth aspect of the invention, in the invention of the vehicle door latch apparatus of any one of the first to seventh aspects, the ratchet restraint can be shifted from either the block position or the release position to the other by manual release operation force.

Effect of the Invention

According to the vehicle door latch apparatus of the first aspect of the present invention, in the configuration in which ratchet member15is prevented from moving to the latch releasing position by ratchet restraint21, pawl portion15aof ratchet member15can be disengaged from latch13while holding ratchet restraint21at the block position. Further, according to the vehicle door latch apparatus of the first aspect of the present invention, pole lever20can be independently moved relative to base lever19.

According to the vehicle door latch apparatus of the second aspect of the present invention, half latch engaging portion13cand full latch engaging portion13dcan be arranged side by side in latch13.

According to the vehicle door latch apparatus of the third aspect of the present invention, blocking surface21censures that ratchet member15is prevented from moving to the latch releasing position, and ratchet member15can be easily returned by inclined cam surface21d.

According to the vehicle door latch apparatus of the fourth aspect of the present invention, ratchet spring17can be rationally arranged without exerting a spring force on base lever19.

According to the vehicle door latch apparatus of the fifth aspect of the present invention, pawl portion15acan be easily disengaged from latch13by rotating base lever19.

According to the vehicle door latch apparatus of the sixth aspect of the present invention, ratchet restraint21can be returned to the block position, which is the initial position, by cam biasing spring23.

According to the vehicle door latch apparatus of the seventh aspect of the present invention, base lever19can be returned from the non-restricted position to the restricted position by the resilient force of cam biasing spring23.

According to the vehicle door latch apparatus of the eighth aspect of the present invention, since ratchet restraint21can be operated by the manual releasing operation force, even if the electric operation is not available, the door opening operation and the door closing operation can still be performed.

DESCRIPTION OF EMBODIMENTS

The foregoing and other objects, features and advantages of the present application will become apparent from the following detailed description with reference to the accompanying drawings that illustrate the present application.

The present embodiment (one embodiment of the present invention) will be explained with reference to the drawings.FIG.1shows the front view of vehicle door latch apparatus10in the unlatched state (the state in which the door is opened). Latch13is rotatably supported on base plate11of vehicle door latch apparatus10by latch shaft12. Latch13is biased in the door opening direction (the releasing direction, or the counterclockwise direction) by latch spring14(shown by an arrow indicating the direction of resilience). Typically, base plate11is fixed to a vehicle door (not shown).

Ratchet member15is rotatably supported on the lower part of base plate11by ratchet shaft16. Ratchet member15is biased in the latch engaging direction by ratchet spring17(shown by an arrow indicating the direction of resilience). In the unlatched state shown inFIG.1, pawl portion15aof ratchet member15is in contact with outer circumference13aof latch13due to the resilient force of ratchet spring17.

When the vehicle door is moved in the door closing direction, striker18that is fixed to the vehicle body (not shown) relatively enters horizontal striker entrance11athat is formed in base plate11to abut against U-shaped striker engaging groove13bof latch13. Striker S then rotates latch13in the door closing direction (the full-latching direction, or the clockwise direction) against the resilient force of latch spring14. Like typical well-known latches, latch13has half latch engaging portion13cand full latch engaging portion13dthat are arranged on the outer circumference thereof.

Latch13normally rotates from the unlatched position shown inFIG.1to the over rotating position shown inFIG.3Cthrough the half-latched position (FIG.3A), where pawl portion15acan be engaged with half latch engaging portion13c, and through the full-latched position (FIG.3B), where pawl portion15acan be engaged with full latch engaging portion13d. InFIG.3C, pawl portion15ais moved to the latch engaging position by the resilient force of ratchet spring17.

After rotating to the over rotating position, latch13is returned in the releasing direction (the counterclockwise direction) by the resilient force of latch spring14and by the repulsive force of a seal member (not shown) that is provided between the door and the vehicle body. Full latch engaging portion13dof latch13then abuts against pawl portion15aat the latch engaging position, as shown inFIG.3D. The force that pushes back latch13in the releasing direction is referred to hereinafter as “latch return force” or “return force”. As explained above,FIGS.3A to3Dshow that the state changes in the order ofFIG.3A,FIG.3B,FIG.3CandFIG.3D. In the following explanation,FIGS.3A to3Dmay be collectively referred to asFIG.3.

The return force that is transmitted from full latch engaging portion13dto pawl portion15ais largely received as main component force F1by ratchet shaft16, as will be described later, but part of the return force is set to act as release component force F2in a direction in which ratchet member15is pushed out in the latch releasing direction (the direction opposite to the latch engaging direction).

As shown inFIGS.5to8, ratchet member15of the present embodiment is divided into base lever19and pole lever20. Base lever19and pole lever20are both insert molded products each including metal plate19aor20a, which is a structural element, and resin cover19bor20b. Resin cover19bis omitted inFIGS.3A to3Dand inFIGS.4A to4E. Note thatFIGS.4A to4Eshow that the state changes in the order ofFIG.4A,FIG.4B,FIG.4C,FIG.4DandFIG.4E. In the following explanation,FIGS.4A to4Emay be collectively referred to asFIG.4.

The base portion of base lever19is rotatably supported by ratchet shaft16, and the base portion of pole lever20is rotatably supported on the end portion of base lever19by connecting shaft15b. In the present embodiment, connecting shaft15bis formed integral with pole lever20, and connecting shaft15bis inserted into shaft hole19cthat is formed in resin cover19b. Pawl portion15ais formed in metal plate20aof pole lever20.

Bifurcated portion19dis formed at the end portion of metal plate19aof base lever19. Connecting shaft15bof pole lever20is arranged inside of bifurcated portion19d. Gap24that is formed between bifurcated portion19dand pole lever20(seeFIG.6) allows pole lever20to rotate relative to base lever19within a predetermined rotation angle.

As shown inFIG.6, ratchet spring17is preferably made of a torsion coil spring. Center coil portion17ais disposed around the outer circumference of connecting shaft15b. One spring leg portion17bis in contact with ratchet shaft16, and the other spring leg portion17cis in contact with pole lever20. According to this spring arrangement, the resilient force of ratchet spring17does not substantially act on base lever19, and the resilient force acts exclusively on bias pole lever20about connecting shaft15bin the latch engaging direction.

Ratchet member15has connecting shaft15bthat is arranged at an intermediate position in the length direction thereof and that rotatably supports base lever19and pole lever20. Therefore, when release component force F2is generated in ratchet member15, release component force F2that is directed in the latch releasing direction acts exclusively on connecting shaft15bthat is positioned at the intermediate position, to bend ratchet member15at the intermediate position, and disengages pawl portion15afrom full latch engaging portion13d. Therefore, it is impossible for ratchet member15alone to keep latch13at the full-latched position.

Ratchet restraint21is disposed in the vicinity of the side of ratchet member15. Ratchet restraint21keeps ratchet member15engaged with latch13by preventing ratchet member15from moving in the latch releasing direction. Ratchet restraint21is rotatably supported on base plate11by pin22. Ratchet restraint21is an insert molded product that includes metal plate21aand resin cover21b. Resin cover21bis omitted inFIGS.3A to3Dand inFIGS.4A to4E.

Metallic plate21aof ratchet restraint21is formed to be a rotating cam. On the outer circumference of metal plate21a, arc-shaped blocking surface21cwhose center is positioned at pin22and inclined cam surface21dthat extends contiguous with blocking surface21care formed. Inclined cam surface21dis a cam surface whose radius from pin22gradually decreases. Blocking surface21cand inclined cam surface21dabut against one of outer walls19eof bifurcated portion19dof metal plate19a.

Ratchet restraint21is rotatable between the block position shown inFIGS.1to3and the release position shown inFIG.4D. The block position corresponds to the initial position of ratchet restraint21. Ratchet restraint21is preferably biased from the release position towards the block position by the resilient force of cam biasing spring23(shown by an arrow indicating the direction of resilience). Manual release operation force from the door opening handle, a door key cylinder or the like, or electric release operation force from a power release mechanism is transmitted to ratchet restraint21. Ratchet restraint21is rotated in the releasing direction from the block position to the release position by the manual or electric release operation force.

When the release operation force is not exerted, ratchet restraint21is held at the block position that corresponds to the initial position by the resilient force of cam biasing spring23. At the block position, blocking surface21cof ratchet restraint21is located on an extension line along which connecting shaft15bof ratchet member15is moved by release component force F2.

In the door closed state inFIG.2, outer wall19eof base lever19is in contact with blocking surface21cat the block position. Therefore, even if the latch returning force acting on latch13is transmitted to pawl portion15aof ratchet member15via full latch engaging portion13d, and release component force F2to push ratchet member15(in particular, connecting shaft15b) in the latch releasing direction is generated in ratchet member15, outer wall19ethat is on the line of action of release component force F2that acts on connecting shaft15bfaces and abuts against blocking surface21cat the block position. Therefore, connecting shaft15bis prevented from moving in the latch releasing direction, and is held where it is positioned. As a result, ratchet member15is not bent at the intermediate position, maintains the engagement between pawl portion15aand full latch engaging portion13d, and keeps the door closed. The position where outer wall19eabuts against blocking surface21cat the block position is the restricted position of base lever19.

In the door closed state inFIG.2, when the manual release operation force or the electric release operation force is transmitted to ratchet restraint21, ratchet restraint21is rotated in the releasing direction against the resilient force of cam biasing spring23.FIG.4shows in detail how ratchet member15operates as ratchet restraint21is rotated in the releasing direction.

When ratchet restraint21is rotated in the releasing direction, blocking surface21cthat faces and that is in contact with outer wall19emoves out of the line of action of release component force F2that acts on connecting shaft15b. Then, base lever19(metallic plate19a) rotates in the latch releasing direction such that it can move from the restricted position to the unrestricted position and such that connecting shaft15bcan move in the latch releasing direction along releasing component force F2. As a result, ratchet member15is bent at the intermediate position. Pawl portion15ais flipped out of full latch engaging portion13din the latch releasing direction, and, as shown inFIG.4D, latch13rotates in the releasing direction to open the door. The non-restricted position of base lever19is a position where connecting shaft15bis moved in the latch releasing direction and where ratchet member15is bent at the intermediate position.

After latch13is rotated in the latch releasing direction, the manual release operation force or the electric release operation force acting on ratchet restraint21is disconnected. Then, ratchet restraint21is rotated in the direction opposite to the latch releasing direction back to the block position by the resilient force of cam biasing spring23. Inclined cam surface21dthat is rotated in the direction opposite to the releasing direction then presses outer wall19eto return base lever19from the non-restricted position to the restricted position by pushing base lever19in the latch engaging direction. As shown inFIG.4E, pawl portion15aof ratchet member15then abuts against outer circumference13aof latch13in order to restore the unlatched state shown inFIG.1.

In the door opened state shown inFIG.1, outer wall19eof base lever19is in contact with blocking surface21cat the block position. Further, outer wall19econtinues to be in contact with blocking surface21cuntil latch13reaches the over rotating position shown inFIG.3D. In the meantime, pole lever20is independently movable in the latch engaging direction due to gap24that is formed between pole lever20and bifurcated portion19d. Therefore, pole lever20is movable to the latch engaging position due to the resilient force of ratchet spring17even in the state shown inFIGS.3A and3B.

When latch13is at the half-latched position shown inFIG.3A, pawl lever20moves to the latch engaging position due to the resilient force of ratchet spring17, and as shown inFIG.11, pawl portion15aof pawl lever20may be half-latched by engaging half latch engaging portion13c. Even in this half latch state, ratchet restraint21holds ratchet member15at the latch engaged position, thereby prevents latch13from rotating in the releasing direction and avoids unexpected opening of the vehicle door.

In the half latch state, pawl portion15acan be disengaged from half latch engaging portion13cby rotating latch13toward the full-latched position. By pushing out latch13toward the full-latched position, connecting slope13ethat is formed between half latch engaging portion13cand full latch engaging portion13dabuts against pole lever20. Since gap24is formed between pole lever20and bifurcated portion19d, pole lever20is then independently pushed out in the latch releasing direction, without rotating base lever19, due to contact with connecting slope13e. As a result, pawl portion15ais disengaged from half latch engaging portion13c.

Therefore, in the configuration in which ratchet restraint21prevents ratchet member15from moving in the latch releasing direction, half latch engaging portion13cand half latch engaging portion13dcan be arranged on the outer circumference of latch13.

When ratchet restraint21is mainly rotated by the power release mechanism, cam biasing spring23may be omitted. In this case, after rotating ratchet restraint21from the block position to the release position, the power release mechanism returns ratchet restraint21from the release position to the block position. In this control operation, it is possible to use rotational position control, such as a limit switch or a contact stopper, or time-controlled rotational position control. When the power release mechanism is used, it is also possible to rotate ratchet restraint21360 degrees from the block position and to stop ratchet restraint21again at the block position. This configuration is advantageous in terms of both the structural and control aspects because the rotation is limited to one direction. In the case of rotating ratchet restraint21360 degrees, in addition to inclined cam surface21dthat is detached from base lever19to allow base lever19to move to the non-restricted position, ratchet restraint21has an additional inclined cam surface that pushes base lever19back to the restricted position.

An embodiment in which ratchet restraint21is connected to door key cylinder25is shown inFIG.12. As shown inFIG.12, arc-shaped slot21eis formed in plastic cover21bof ratchet restraint21, and slot21eis connected to pivoting link26of door key cylinders25via rod27. Rod27is positioned at an intermediate part of slot21ein the longitudinal direction thereof to provide a predetermined space on both sides. This enables ratchet restraint21to rotate between the block position and the release position without being affected by door key cylinder25. Further, by using door key cylinder25to rotate pivoting link26from the neutral position in the releasing direction or in the returning direction and then to rotate pivoting link26back to the neutral position, it is possible to move ratchet restraint21to the release position or to the block position, respectively.

Since electrical components, such as a power release mechanism that is coupled to ratchet restraint21, cannot be completely free of electrical problems, it is desirable that ratchet restraint21be coupled both to the power release mechanism and to door key cylinder25. By doing so, even if the power release mechanism becomes inoperable during operation, it is possible to rotate door key cylinder25in the releasing direction to move ratchet restraint21to the release position, thereby to move ratchet member15to the latch releasing position, and thereby to release latch13to make the vehicle door openable. In addition, since ratchet restraint21can be returned to the block position, which is the initial position, by rotating back door key cylinder25after the vehicle door is opened, the vehicle door can be stably closed next time.

In the above description, the friction force between ratchet member15and ratchet restraint21, which is generated when ratchet restraint21is rotated from the block position inFIG.2to the release position, can be effectively reduced, as compared to a conventional apparatus, and further reduction in the release operation force for rotating ratchet21can be expected.

The latch returning force for latch13is transmitted as external force P1from the contact point between full latch engaging portion13dand pawl portion15ato connecting shaft15b, and is then transmitted as external force P2from connecting shaft15bto ratchet shaft16. These external forces P1and P2are separated into main component force F1and release component force F2.

Pawl portion15amay engage full latch engaging portion13deither at a deep position or at a shallow position. Therefore, in a strict sense, the contact point of pawl portion15ais different each time. Such variation of the contact point leads to the variation of the direction and the strength of external force P1that is transmitted to connecting shaft15b. The same applies to the direction of external force P2. As a result, main component force F1and release component force F2are variable.

In order to avoid such variation, pawl portion15aof the present embodiment is formed as an arc surface whose center is positioned at connecting shaft15b. By forming pawl portion15aas an arc surface, even if the position where pawl portion15aengages full latch engaging portion13dis shifted, external force P1always acts on the axial center of connecting shaft15b. As a result, the direction and the strength of external force P1is stabilized, and a change in external force P2, main component force F1and release component force F2can be prevented. Since release component force F2becomes constant, the contact pressure between ratchet restraint21and ratchet member15becomes constant, and the release operation force of ratchet restraint21stably acts on ratchet member15.

The latch returning force is transmitted to ratchet member15both from full latch engaging portion13dand from half latch engaging portion13c. Although some part of the above explanation only refers to the relationship between full latch engaging portion13dand pawl portion15a, the same applies to the relationship between half latch engaging portion13cand pawl portion15a.

LIST OF REFERENCE NUMERALS