Hinge mechanism

The embodiment includes a hinge, a pivot shaft, a cam, and a cam follower. The pivot shaft includes an engaging portion bound by two curved surfaces and two non-rotatable surfaces. The cam is non-rotatably sleeved on the engaging portion of the pivot shaft and defines a noncircular hole and two cutouts. The noncircular hole is bound by two first contact surfaces and two second contact surfaces. The second contact surfaces are tangent to the curved surfaces of the engaging portion of the pivot shaft. The cam follower is rotatably sleeved on the engaging portion of the pivot shaft and resists the cam. The cam follower forms two peaks engaging with the cutouts in the cam.

This application claims all benefits accruing under 35 U.S.C. §119 from China Patent Application No. 201010131461.4, filed on Mar. 24, 2010 in the State Intellectual Property Office of the People's Republic of China, the contents of which are hereby incorporated by reference.

BACKGROUND

1. Technical Field

The present disclosure generally relates to hinge mechanisms, and more particularly to a hinge mechanism applied in an electronic device.

2. Description of Related Art

Many electronic devices include hinge mechanisms. A hinge mechanism generally includes a cam and a cam follower resisting the cam to ensure that one part is capable of rotating or being maintained at predetermined positions relative to the other. Thus, a changeable friction force is generated therebetween.

A commonly used hinge mechanism includes a pivot shaft, two frames, and two special purpose irregular washers resisting each other. One irregular washer forms two protrusions and the other irregular washer defines two cutouts engaging with the protrusions thereof. The frames and the irregular washers are sleeved on the pivot shaft. The main frame is connected to the display frame of the electronic device. The irregular washer with the protrusions defines a noncircular hole therein corresponding to the cross-section of the pivot shaft, and the irregular washer with the cutouts defines a substantially circular hole therein and forms a locking pole fixed to one of the frames. Therefore, the irregular washer with the protrusions rotates with the pivot shaft relative to the irregular washer with cutouts and the frame is fixed to the irregular washer with cutouts.

In use, the protrusion washer slides along the pivot shaft and resists different portions of the recess washer, and thereby, the resisting force along the axis direction of the pivot shaft is changed. However, since the shape and size of the noncircular hole in the irregular washer with protrusions is similar to that of the cross-section of the pivot shaft, the inner sidewalls of the noncircular hole have a relatively large contact surface with the pivot shaft, which prevents the irregular washer from sliding along the pivot shaft smoothly. Furthermore, the irregular washer and the pivot shaft are scraped severely.

Therefore, there is room for improvement within the art.

DETAILED DESCRIPTION

The present embodiment of a hinge may be applied in any electronic device with two or more hinged parts, such as notebook computers, LCD monitors, or DVD (digital video disc) players.

Referring toFIGS. 1 and 2, a hinge100includes a pivot shaft10, a first bracket20, a second bracket30, two flat washers40, a restriction member50, a resisting assembly60, a resilient assembly70, a friction washer80, and a fastener90sleeved on the pivot shaft10. The first bracket20, the second bracket30, the flat washers40, the restriction member50, the resisting assembly60, the resilient assembly70, the friction washer80, and the fastener90are respectively sleeved on the pivot shaft10.

The pivot shaft10includes a head portion11, a flange13, and an engaging portion15. The head portion11and the engaging portion15are formed at opposite sides of the flange13, and both the head portion11and the engaging portion15have noncircular cross-sections. The engaging portion15includes an exterior surface151bound by two non-rotatable surfaces1511and two curved surfaces1513. The non-rotatable surfaces1511are formed in a manner opposing each other and the curved surfaces1513are also formed in a manner opposing each other. The pivot shaft10further has a threaded portion (not labeled) at a distal end of the engaging portion15. Alternatively, the engaging portion15of the pivot shaft10may include one curved surface1513and three or more non-rotatable surfaces1511, or include one curved surface1513and one non-rotatable surface1511.

The first bracket20includes a sleeve portion21and a connection portion23bent from one end of the sleeve portion21. The sleeve portion21defines a sleeve hole211with a shape and size similar to that of the cross-section of the head portion11of the pivot shaft10. The connection portion23defines a number of assembly holes (not labeled) for connection to a part of an electronic device. In the illustrated embodiment, the sleeve portion21and the connection portion23are substantially plate-shaped and substantially perpendicular to each other.

The second bracket30includes a rotatable portion31and a fixing portion33bent from one end of the rotatable portion31. The rotatable portion31defines a shaft hole311with a substantially circular shape and a restriction hole313adjacent to the shaft hole311. The fixing portion33defines a number of assembly holes (not labeled) for connection to the other part of the electronic device. In the illustrated embodiment, both the rotatable portion31and the fixing portion33are plates and substantially perpendicular to each other.

Each flat washer40defines a central hole (not labeled) and a number of oil grooves (not labeled) adjacent to the central hole. The number of the flat washers40can be one or more than two.

The restriction member50forms an extended portion51extending from part of an edge thereof, and defines a noncircular hole (not labeled) in a central portion thereof.

The resisting assembly60includes a cam61and a cam follower63resisting each other.

Also referring toFIGS. 3 through 5, the cam61is cylindrical and defines a noncircular hole611at a central portion thereof, two cutouts613recessing from one end, and a first mistake-proof structure615recessing from an exterior side surface. The number of the cutouts613can be one or more than two.

The noncircular hole611is bound by two first contact surfaces6111opposing each other and two second contact surfaces6113opposing each other. The first contact surfaces6111correspond to the non-rotatable surfaces1511of the pivot shaft10, and the second contact surfaces6113correspond to the curved surfaces1513. That is, the first contact surfaces6111are flat, and the second contact surfaces6113are curved in the illustrated embodiment. The cam61defines two slots6115respectively recessing from two first contact surfaces6111, and the cam61further forms a round-corner6117at a portion where the first contact surfaces6111and the second contact surfaces6113intersect at the end where the cutouts613recess. The curvature of the second contact surfaces6113is less than the curvature of the curved surfaces1513of the pivot shaft10, such that the second contact surfaces6113are tangent to the curved surfaces1513when the pivot shaft10passes through the noncircular hole611of the cam61. Therefore, each second contact surface6113provides a line-contact between the cam61and the pivot shaft10.

Alternatively, the second contact surfaces6113may be wavy or partially spherical. The noncircular hole611may be bound by one second contact surface6113and three first contact surfaces6111, or bound by one second contact surface6113and one first contact surface6111corresponding to the structure of the engaging portion15of the pivot shaft10. The cam61can define multiple slots6115recessing from each first contact surface6111.

A bottom surface (not labeled) of each cutout613is connected with an end surface (not labeled) from which the cutouts613are recessed with two slopes in a circumferential direction of the cam61.

The cam follower63defines a central hole631which is substantially circular. The cam follower63forms two peaks633at one end opposing the cam61, corresponding to the cutouts613in the cam61. The cam follower63further forms a restriction block635at the other end of the cam follower63and a fixing pole637protruding from the restriction block635. The cam follower63defines a second mistake-proof structure639recessing from the exterior side thereof corresponding to the first mistake-proofing structure615in the cam61. A height of each peak633of the cam follower63is less than a depth of each cutout613in the cam61. The restriction block635is formed adjacent to an edge of the cam follower63and defines an arched recess6351. The distance from the side surface (not labeled) to the center of the cam follower63is greater than the distance from the edge of the restriction member50to the center thereof, but less than the distance from the extended portion51of the restriction member50to the center thereof, such that the restriction member50excepting the extended portion51is capable of rotating in the arched recess6351. Thereby, the rotating range of the restriction member50is restricted. The number of the peaks633of the cam follower63corresponds to the number of the cutouts613in the cam61. Alternatively, the first and the second mistake-proofing structures615and639can be protrusions or other structures instead.

The cam follower63can be omitted, and the peaks633are formed on the rotatable portion31of the second bracket30directly. That is, the cam61resists the rotatable portion31of the second bracket30directly. Also, the cam60can form peaks, and the element resisting the cam60defines cutouts to engage with the corresponding peaks of the cam61.

The resilient assembly70includes a number of disk-shaped spring washers and which can be a compression spring. The friction washer80defines a central hole (not labeled) corresponding to the cross-section of the engaging portion15of the pivot shaft10. The fastener90is a lock nut and can be a pin passing through the pivot shaft10in a radial direction thereof, and correspondingly, the distal end of the engaging portion15of the pivot shaft10defines a pin hole.

During assembly of the hinge100, the head portion11of the pivot shaft10is inserted into the sleeve hole211of the first bracket20, such that the pivot shaft10is non-rotatably connected with the first bracket20. The engaging portion15is inserted through one flat washer40, the second bracket30, the other flat washer40, the restriction member50, the cam61, the cam follower63, the resilient assembly70, the friction washer80, and finally engaged with the fastener90. The elements sleeved on the pivot shaft10resist each other tightly.

During the assembly process, the extended portion51of the restriction member50avoids the restriction block635and the fixing pole637of the cam follower63. In addition, the mistake-proofing structure615in the cam61and the mistake-proofing structure639in the cam follower are respectively maintained. The fixing pole637of the cam follower63is received in the restriction hole313in the rotating portion31of the second bracket30. The second contact surfaces6113of the noncircular hole611in the cam61contact the curved surfaces1513of the engaging portion15of the pivot shaft10by line-contact. Alternatively, the resisting assembly60can be positioned between the flange13of the pivot shaft10and the rotating portion31of the second bracket30.

In use, the pivot shaft10, the restriction member50, the cam61, the friction washer80, and the fastener90rotate with the first bracket20, and the cam follower63and the resilient assembly70rotate with the second stand30. During the rotation process, the restriction member50rotates relative to the cam follower63but stops rotating when a side of the extended portion51is blocked by the restriction block635. Thus, the first bracket20stops rotating relative to the second bracket30. The rotation angle of the hinge100is restricted to a predetermined range by the engagement between the restriction member50and the cam follower63.

In the hinge100, the curved surfaces1513of the engaging portion15of the pivot shaft10are tangent to the second contact surfaces6113of the noncircular hole611of the cam61. Furthermore, the non-rotatable surfaces1511of the engaging portion15partially contact the first contact surfaces6111of the noncircular hole611because of the slots6115in the noncircular hole611. Therefore, the contact area between the pivot shaft10and the cam61is reduced, such that the friction force therebetween is reduced at the same time. The cam61is capable of sliding along the pivot shaft10smoothly and the cam61and the pivot shaft10is not easily abraded.

Because the height of each peak633of the cam follower63is less than the depth of each cutout613of the cam61, the peaks633do not contact the bottom surface of the cutouts613. Therefore, the peaks633and the bottom surfaces of the cutouts613do not easily abrade. Furthermore, the bottom surface633of each cutout613is connected with the end surface of the cam61in a circumferential direction of the cam61with the slopes, such that the peaks633of the cam follower63slide into or slide out of the cutouts613of the cam61smoothly and do not suddenly fall into the cutouts613. Thus, an impact noise between the bottom surfaces of the cutouts613and the peaks633is avoided, and a better handle manipulation feeling can be achieved.

The first mistake-proofing structure615in the cam61and the second mistake-proofing structure639in the cam follower63can facilitate the assembly of the cam61and the cam follower63and thus improve the efficiency of the assembly process of the hinge100.

Because of the round-corner6117formed in the cam61, the pivot shaft10is passed easily through the noncircular hole611of the cam61and not easily scraped. Therefore, the assembly process is further improved.

The first bracket20and the second bracket30can be omitted, and two ends of the pivot shaft10are respectively inserted into two parts of the electronic device. Furthermore, the restriction block635of the cam follower63can have a greater size such that the cam follower63is capable of directly connecting with one part of the electronic device.