Abstract:
A hinge for a vehicle lid comprises a main spring means ( 112 ) operable to urge the hinge into an open position, and a device ( 114 ) for assisting the initial opening of the hinge, the device comprising an elongate body in which a plunger ( 116 ) is sliceable, the plunger being engageable with the hinge, and spring means disposed in the body and acting on the plunger to urge it into an extended position. The plunger is cylindrical and is retained in a cylindrical cavity in the body by an annular fastening, the fastening being formed with one or more radially projecting ribs which engage with an annular recess at the opening of the cylindrical cavity to attach the fastening means to the body. The plunger is formed such that in the extended position disengagement of the one or more ribs from the annular recess is inhibited, preventing the plunger from forcing the fastening out of the body. A bracket extends from a wall of the body to define a slot between the member and the wall, enabling the device to be mounted upon a link of the hinge.

Description:
FIELD OF THE INVENTION 
     This invention is concerned with a vehicle lid hinge having a main spring means operable to urge the hinge into an open position and a device for assisting the initial opening of the hinge, and to a device for use on such a hinge. 
     BACKGROUND TO THE INVENTION 
     Four-link hinges are often used on the boot lids of European cars because they intrude less into the boot space when the lid is closed, and enable the lid to be opened to a greater angle from its closed position than the more conventional hinge comprising a single curved link. Use of such four-link hinges on car boot lids increases the usable boot space and improves access thereto. 
     Four-link hinges in general comprise a gas strut connected between two of the links and operable to open the hinge by acting upon said two links. However, it has been found that the line of action of the gas strut is such that it acts to open the hinge only once the hinge is partially opened. This means that the boot lid initially seems to be excessively heavy to a person attempting to open it, and prevents the lid from being opened from inside the car using a remote catch, since the boot lid is held closed by its weight and locks again as soon as the remote catch is released. 
     Several arrangements have been proposed for opening the hinge to the point where the gas strut starts to act, including, in one arrangement a folded Ieaf spring attached to a first link and acting upon a second link, and in a second arrangement a cam pivotally attached to one of the links such that the gas strut initially acts upon the cam rather than the link itself to open the hinge. 
     Car manufacturers have been slow to accept either arrangement for a number of reasons, but principally because of their appearances, and their tendencies to distort the lid when in the closed position. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided a hinge for a vehicle lid, the hinge comprising a main spring means, for example a gas strut, operable to urge the hinge into an open position, and a device for assisting the initial opening of the hinge, the device comprising an elongate body in which a plunger is slidable, the plunger being engageable with another portion of the hinge to provide said assistance, and spring means disposed in the body and acting on the plunger to urge it into an extended position. 
     Thus the invention provides a hinge for a vehicle lid having a device for assisting the initial opening of the hinge that is discrete in appearance and does not need elements that can distort the boot lid when the lid is in the closed position. 
     Preferably the hinge is a four-link hinge. 
     Preferably the hinge comprises a body link for attaching to a vehicle body, a lid link for attaching to a vehicle lid, short and long links joining the body and lid links, and the main spring means comprises a gas strut attached between the body and lid links, the device being attached to the long link such that the plunger acts upon the end of the gas strut attached to the lid link. 
     Alternatively the device may advantageously be attached to the long link such that the plunger acts directly upon the lid link. 
     The long link may advantageously be cranked or kinked to accommodate the device within the hinge without increasing the overall width of the hinge. 
     Preferably the plunger engages with the hinge only when the hinge is in a closed position and during the initial opening of the hinge from the closed position. 
     Preferably the plunger is retained in the body by a fastening means attached to the elongate body. 
     Preferably the elongate body has a cylindrical internal cavity having an opening to accommodate the plunger, the plunger being cylindrical and the fastening means being an annular fastening. 
     Preferably the elongate body is formed with an annular recess at the opening of the cylindrical internal cavity and the annular fastening is formed with one or more radially projecting ribs, which ribs engage with the annular recess. 
     According to a particularly advantageous feature of the invention the plunger may be so shaped that, when in the extended position, it exerts a radial outward force upon the annular fastening and forces the one or more radially projecting ribs into the annular recess to strengthen the attachment of the annular fastening to the elongate body. 
     The spring means may advantageously comprise a mechanical spring, preferably a helical compression spring. 
     Advantageously the spring means may be damped such that the plunger moves to the extended position at a controlled rate. 
     Preferably at least one of, and more preferably all of, the elongate body, plunger and annular fastening may be formed from rigid plastics material. 
     The rigid plastics material may advantageously be an acetal resin. 
     Preferably the device has a flexible member which is so positioned as to define a slot between the flexible member and a wall of the elongate body, thereby enabling the device to be mounted upon a first link of the hinge. 
     This feature enables the device to be fitted to the rest of the hinge after the latter has been assembled. 
     Typically the hinge is a hinge of a vehicle boot lid but may be, for example, the hinge of a vehicle bonnet. 
     Advantageously the elongate body may further comprise a stud which projects into said slot to engage with an aperture in said first link, such that said flexible member may be sufficiently deformed to enable the stud to pass over the thickness of the link until the stud engages with the aperture, thereby securing the device in position upon the link. 
     Alternatively the flexible member may advantageously comprise an aperture for receiving a pin, the aperture being located such that when the device is mounted upon said first link of the hinge, the aperture in the flexible member and an aperture in said first link are in line. 
     Preferably the wall of the elongate body on the opposite side of the slot from the flexible member and in line with said aperture is formed with a recess for receiving one end of the pin. 
     Preferably the aperture in the hinge link is greater in size than the aperture in the flexible member, and the pin is formed with radially projecting barbs, such that when the device is mounted upon the hinge link, the pin may be pushed into the aperture in the member until the barbs pass through the member, whereupon the barbs expand into the aperture in the link, thereby retaining the pin in the flexible member. 
     Preferably, the flexible member comprises a finger, which may, for example, comprise a bracket, having a connecting portion which connects the finger to the body and which extends perpendicularly to the body. 
     According to a second aspect of the invention there is provided a four-link hinge for a vehicle lid comprising a main spring means, for example a gas strut, operable against one of the links to urge the hinge into an open position, and a device for assisting the initial opening of the hinge, wherein the device comprises an elongate body in which a plunger is retained by an annular fastening attached to the elongate body, and spring means for urging the plunger into an extended position for engagement with the hinge. 
     According to a third aspect of the invention there is provided a device for use with a hinge in accordance with the first or second aspect of the invention, comprising an elongate body in which a plunger is sliceable, the plunger being engageable with the hinge, and spring means disposed in the body and acting on the plunger to urge it into an extended position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
     FIG. 1 is a section of a first embodiment of a spring device in accordance with the invention, the device being shown with its plunger in a retracted position; 
     FIG. 2 is a section of the first embodiment of the spring device showing the plunger in an extended position; 
     FIG. 3 is a section of a second embodiment of the spring device showing the plunger in a retracted position; 
     FIG. 4 is a section of the second embodiment of the spring device showing the plunger in an extended position; 
     FIG. 5 is a side view of a first embodiment of a four-link hinge in accordance with the invention, the hinge being shown in its open position; 
     FIG. 6 is a plan view of the first embodiment of the four-link hinge when closed; 
     FIG. 7 is a perspective view of a second embodiment of a four-link hinge incorporating a spring device, the hinge being shown in its open position; and 
     FIG. 8 is a perspective view of the second embodiment of the four-link hinge when closed. 
    
    
     DESCRIPTION 
     FIGS. 1 and 2 show a first embodiment of the spring device having an elongate body  10 , a helical compression spring  12 , a plunger  14  and a fastening  16 . 
     The elongate body  10  is generally cup-shaped, having a wall  18  which has four vertical external surfaces. The body has an open, upper end and a closed, lower end, the lower end being closed by a base  20 . The internal surface of the wall  18  is generally cylindrical but has an annular recess  22  a short distance from the open end of the body. A guide  24  constituted by a tubular member extends from the centre of the internal surface of the base  20  to the open end of the body. 
     The internal surface of the wall  18  and the external surface of the guide  24  define, respectively, the outer and inner limits of an annular cavity in the body. The internal surface of the guide  24  is cylindrical and defines a cylindrical cavity in the body. The annular and cylindrical cavities are coaxial. 
     A flexible bracket  26  constituted by a right-angled member projects from near the top of one of the four vertical external surfaces of the wall  18  and extends parallel to, and for approximately two thirds of the length of, said surface, to define a slot between the surface and the bracket  26  which enables the spring device to be mounted upon a link of a hinge. A circular stud  28  projects from the centre of the lower end of the surface below the slot. Although not shown, the slot would normally be occupied by a link of a hinge, and the circular stud  28  would engage with an aperture in the link, thereby securing the spring device to the link. 
     To attach the spring device to the hinge link the flexible bracket  26  is deformed by bending it away from the wall of the body to enable the link to pass between the circular stud and the lower end of the bracket into the slot, until the stud engages with the aperture in the link, whereupon the bracket returns to its undeformed shape. 
     The wall  18 , base  20 , guide  24 , bracket  26  and stud  28  are all integrally moulded as a single component. 
     The plunger  14  is generally cup-shaped, having a wall  30  with a cylindrical external surface. The plunger has an open, lower end and a closed, upper end, the upper end being closed by the plunger head  32 . A cylindrical shaft  34  extends from the centre of the internal surface of the plunger head  32  to the open end of the plunger. The diameter of the shaft  34  is slightly less than the internal diameter of the guide  24 . The internal surface of the wall  30  has a lower and an upper portion, the upper and lower portions being cylindrical and the diameter of the lower portion being greater than the diameter of the upper portion. The upper and lower portions are joined by a radial shoulder  36 . The lower portion of the internal surface of the wall and the surface of the shaft  34  define the outer and inner limits, respectively, of a lower annular cavity in the plunger. The upper portion of the internal surface of the wall and the surface of the shaft  34  define the outer and inner limits, respectively, of an upper annular cavity in the plunger. 
     Contiguous upper and lower flanges  38  and  40  are formed at the lower end of the external surface of the wall  30  of the plunger. The external diameter of the upper flange  38  is less than that of the lower flange  40 . The external diameter of the lower flange  40  is slightly less than the diameter of the internal surface of the wall  18  of the body  10 . 
     The wall  30 , plunger head  32 , shaft  34 , shoulder  36 , upper flange  38  and lower flange  40  are integrally moulded as a single component. 
     The internal diameter of the spring  12  is slightly greater than the external diameter of the guide  24 . The external diameter of the spring is slightly less than the diameter of the lower portion of the internal surface of the wall  30  of the plunger. 
     The fastening  16  is generally annular and has an internal and an external surface, each of which is generally cylindrical. An annular lip  42  extends inward from the upper end of the internal surface and an annular rib  44  projects radially outward from the lower end of the external surface. The internal diameter of the lip  42  is slightly greater than the external diameter of the plunger. The diameter of the internal surface of the fastening is slightly greater than the external diameter of the upper flange  38  but less than the external diameter of the lower flange  40 . The external diameter of the rib  44  is greater than the diameter of the internal surface of the wall  18  of the body. 
     The spring device is assembled by inserting the upper end of the spring  12  into the lower annular cavity in the plunger until the upper end of the spring engages with the radial shoulder  36 . The lower end of the spring, which protrudes from the open end of the plunger, is placed over the guide  24  and pressed towards the lower end of the body, until the lower end of the spring engages with the internal surface of the base  20 . The plunger is depressed into the body, in opposition to the spring, which acts against the radial shoulder  36  and the base  20  of the body to urge the plunger out to the body, the shaft  34  being accommodated in the guide  24  and the guide being accommodated in the upper and lower annular cavities in the plunger. 
     The fastening is placed over the upper end of the plunger and, with the plunger depressed into the body in opposition to the spring, the lower end of the fastening is forced into the open end of the body. The external diameter of the rib  44  results in a slight radial compression of the fastening as it is forced into the open end of the body. The radial compression deforms the lower end of the fastening away from the internal surface of the wall  18  of the body and towards the external surface of the wall  30  of the plunger. When the fastening has been forced a sufficient distance into the open end of the body for the rib  44  and the recess  22  to be in alignment, the rib engages with the recess, enabling the fastening to expand radially to its undeformed shape. Slight radial compression of the fastening to disengage the rib from the recess is therefore necessary before the fastening can be removed from the body. 
     When the plunger is released from its depressed position, the spring urges the plunger towards the open end of the body, until the plunger reaches its extended position when the lower flange  40  of the plunger engages with the lower end of the fastening. With the lower flange  40  engaged with the lower end of the fastening, the upper flange  38  prevents radial compression of the fastening. Thus the plunger is prevented in its extended position from forcing the fastening out of body. 
     The lip  42  inhibits the ingress of dust and the like into the spring device. 
     The lip  42  and rib  44  are integrally moulded parts of the annular fastening. 
     The elongate body  10 , cylindrical plunger  14  and annular fastening  16  are all moulded from an acetal resin. 
     In FIG. 1 the plunger  14  is shown in a retracted position relative to the elongate body  10  due to a force acting upon the plunger in opposition to the spring  12 . 
     In FIG. 2 the plunger  14  is shown in an extended position relative to the elongate body  10 . The further extension of the plunger due to the action of the spring  12  is prevented by the engagement of the lower flange  40  with the lower end of the annular fastening  16 . 
     FIGS. 3 and 4 show a second embodiment of the spring device comprising an elongate body  46 , a helical compression spring  48 , a plunger  50  and a fastening  52 . 
     The elongate body  46  is of a broadly similar shape to the elongate body  10 , having a wall  54  with four external surfaces, a base  56  and a bracket  58  constituted by a right-angled member which projects from one of the four external surfaces of the wall  54 . The internal surface of the wall  54  is cylindrical but is formed with an annular recess  60  a short distance from the upper, open end of the body. The base  56  is formed with a circular aperture at its centre and an annular ridge  62  projects a short distance from the internal surface of the base around the aperture into the body. The internal surface of the wall, the annular ridge  62  and the circular aperture are coaxial. 
     The bracket  58  extends parallel to, and along the whole length of, the external surface of the wall from which it projects, so as to define a slot between the bracket and said external surface, which enables the spring device to be mounted upon a link of a hinge. The bracket  58  has a circular aperture  64  at its centre. A circular recess  66  is formed in the external surface, having the same diameter as, and in line with, the aperture  64 . 
     The wall  54 , base  56 , bracket  58  and annular ridge  62  are all integrally moulded as a single component. 
     The plunger  50  is generally cup-shaped and cylindrical, having a wall  68  which is open at its lower end and closed at its upper end by the plunger head  70 . The internal surface of the wall  68  defines a lower cylindrical cavity in the plunger. The lower end of the external surface of the wall  68  is formed with a frusto-conical skirt  72 , which tapers outwards in the direction of the lower end of the plunger. The diameter of the skirt  72  at its widest point is slightly less than the diameter of the internal surface of the wall of the body. The internal surface of the wall  68  has a lower and an upper portion, the lower and upper portions being cylindrical and the diameter of the of the lower portion being greater than the diameter of the upper portion. The upper and lower portions are joined by a radial shoulder  74 . The upper and lower portions, respectively, of the internal surface of the wall define upper and lower cylindrical cavities in the plunger. 
     The wall  68 , plunger head  70 , skirt  72  and shoulder  74  are all integrally moulded as a single component. 
     The internal diameter of the spring  48  is slightly greater than the external diameter of the the annular ridge  62 . The external diameter of the spring is slightly less than the diameter of the lower portion of the internal surface of the wall  68  of the plunger. 
     The fastening  52  is generally annular and has an inner and an outer surface, each of which is generally cylindrical. An annular rib  76  projects radially outward from the lower end of the external surface. The diameter of the internal surface of the fastening is slightly greater than the external diameter of the plunger. The internal surface of the lower end of the fastening has a frusto-conical portion  78  which tapers outwards in the direction of the lower end of the fastening. The diameter of the frusto-conical portion  78  of the internal surface of the fastening at its widest point is slightly less than the diameter of the skirt  72  at its widest point. The external diameter of the rib  76  is greater than the diameter of the internal surface of the wall  54  of the body. 
     The manner of assembly of the second embodiment of the spring device is broadly similar to that of the first embodiment described in relation to FIGS. 1 and 2. The upper end of the spring  48  is inserted into the lower cylindrical cavity in the plunger until the upper end of the spring engages with the radial shoulder  74 . The lower end of the spring, which protrudes from the open end of the plunger, is inserted into the open end of the body and pressed towards the lower end of the body, until the lower end of the spring passes over the annular ridge  62  and engages with the internal surface of the base  56 . The plunger is depressed into the body, in opposition to the spring, which acts against the radial shoulder  74  and the base  56  of the body to urge the plunger out to the body. 
     The fastening is placed over the upper end of the plunger and, with the plunger depressed into the body in opposition to the spring, the lower end of the fastening is forced into the open end of the body. The external diameter of the rib  44  results in a slight radial compression of the fastening as it is forced into the open end of the body. The radial compression deforms the lower end of the fastening away from the internal surface of the wall  54  of the body and towards the external surface of the wall  68  of the plunger. When the fastening has been forced a sufficient distance into the open end of the body for the rib  76  and the recess  60  to be in alignment, the rib engages with the recess, enabling the fastening to expand radially to its undeformed shape. Slight radial compression of the fastening to disengage the rib from the recess is therefore necessary before the fastening can be removed from the body. 
     When the plunger is released from its depressed position, the spring urges the plunger towards the open end of the body, until the plunger reaches its extended position when the frusto-conical skirt  72  of the plunger engages with the frusto-conical portion  78  of the internal surface of the lower end of the fastening. The engagement of the skirt  72  with the internal surface of the fastening exerts a radial outward force on the lower end of the fastening which strengthens the engagement of the rib  76  with the recess  60 . Thus the plunger is prevented in its extended position from forcing the fastening out of body. 
     In FIG. 3 the plunger  50  is shown in a retracted position relative to the elongate body  46  due to a force acting upon the plunger head in opposition to spring  48 . 
     In FIG. 4 the plunger  50  is shown in an extended position relative to the elongate body  46 . The further extension of the plunger due to the action of the spring  48  is prevented by the engagement of the frusto-conical skirt  72  with the frusto-conical portion  78  of the fastening. 
     In FIG. 4 a pin  80  is shown pushed into the circular aperture  64  and circular recess  66  of FIG.  3 . The pin is formed with two deformable barbs  82  which close as the pin is pushed into the hole  64 , then open into the slot between the bracket  58  and the external surface of the wall  54 , to prevent the removal of the pin. Although not shown, the slot would normally be occupied by a link of a hinge, and the pin would pass through an aperture in the link, the aperture having a greater diameter than the circular aperture  64  in order to enable the barbs  82  to open, thereby securing the spring device to the link. 
     With reference to FIGS. 5 and 6, either embodiment of the spring device is attached in use to a first embodiment of a four-link hinge comprising a body link  84  attachable to the body of a vehicle, a long link  86 , a short link  88 , a lid link  90  attachable to the vehicle lid, a gas strut  92  and the spring device  94  including a plunger  96 . For the purpose of simplicity, the vehicle lid and body have not been shown. 
     The construction and operation of the first embodiment of the four-link hinge are described with reference to FIGS. 5 and 6. 
     The long and short links  86  and  88  respectively are attached by pivots at their first ends to the body link  84  and at their second ends to the lid link  90 . The gas strut  56  is attached by a pivot  98  at its first end to the body link  84  and by a pivot  100  at its second end to the lid link  90 . The spring device  94  is mounted upon the long link  86  such that when the hinge is closed, the plunger  96  of the spring device  94  is depressed by the gas strut pivot  100 . 
     When the hinge is closed the body link  84 , lid link  90  and gas strut  92  are substantially parallel. The initial opening of the hinge comprises, inter alia, a rotation of the lid link  90  relative to the body link  84  about the pivot  102  which attaches the lid link  90  to the short link  88 . The component of the force produced by the gas strut acting on pivots  98  and  100  to rotate the lid link  90  about pivot  102  relative to the body link  84  is, to a reasonable approximation, proportional to the sine of the angle between the lid and body links. Thus when the hinge is closed, the angle between the lid and body links is small and the sine of this angle, and hence the component of the force produced by the gas strut which tends to open the hinge, is vanishingly small. 
     The plunger  96  of the spring device is depressed by the gas strut pivot  100  when the hinge is closed, which compresses the compression spring (not shown) in the spring device. When the lid is unlatched, the force exerted by the compression spring on the plunger  96  causes the plunger to act against the gas strut pivot  100 . The force exerted by the plunger on the pivot  100  gives rise to an opening torque about pivot  98 . The geometry of the hinge is such that this is greater than the closing torque created by the reaction force exerted by the device  94  on the link  86 . The plunger  96  thus rotates the lid link  90  upwards relative to the body link  84  about the pivot  102 . As the angle between the lid and body links increases due to the action of the spring device, the component of the force exerted by the gas strut which tends to rotate the lid and body links relative to one another increases. By the time the plunger reaches its extended position and ceases to exert any force on the gas strut pivot  100 , the component of the force exerted by the gas strut which tends to rotate the lid and body links relative to one another is sufficient to prevent the hinge from returning to the closed position. 
     With reference to FIGS. 7 and 8, either embodiment of the spring device is attached in use to a first embodiment of a four-link hinge comprising a body link  104  attachable to the body of a vehicle, a long link  106 , a short link  108 , a lid link  110  attachable to the vehicle lid, a gas strut  112  and the spring device  114  including a plunger  116 . For the purpose of simplicity, the vehicle lid and body have not been shown. 
     The construction and operation of the four-link hinge are described with reference to FIGS. 7 and 8. 
     The construction and operation of the hinge shown in FIGS. 7 and 8 are broadly similar to those of the hinge shown in FIGS. 5 and 6. The lid link  110  has horizontal and vertical portions  120  and  122  respectively. The spring device  114  is mounted on the long link  104  such that when the hinge is closed, the plunger  116  of the spring device is depressed by the horizontal portion  120  of the lid link. In this embodiment of the hinge the spring device is located closer to the pivot  118  about which the lid link  110  rotates relative to the body link  104 , than the spring device in the first embodiment is located to the corresponding pivot  102 . Therefore, a spring device in the second embodiment produces a moment about the pivot  118  that is smaller than the moment that would be produced about the corresponding pivot  102  by the same spring device in the first embodiment. However the angle through which the lid link of the second embodiment rotates relative to the body link before the plunger ceases to exert a force on the lid link is correspondingly greater in the second embodiment than in the first.