Hinge assembly

A hinge assembly includes a shaft, a leaf, a rotatable joint, a positioning member, an elastic engaging member, and a fastening member. The leaf is non-rotatably mounted on the shaft, and the rotatable joint is rotatably mounted on the shaft. The positioning member includes an engaging surface, and is non-rotatable relative to the rotatable joint. The elastic engaging member includes an engaging surface, and is non-rotatably sleeved on the shaft. The fastening member is engaged on the shaft. One of the engaging surfaces of the positioning member and the engaging member forms an engaging protrusion, and the other one of the engaging surfaces of the positioning member and the engaging member defines an engaging slot engaging with the engaging protrusion.

BACKGROUND

1. Field of the Invention

The present disclosure generally relates to hinge assemblies and, particularly, to a hinge assembly used in a foldable electronic device having a top cover and a main body.

2. Description of the Related Art

Foldable electronic devices, such as notebook computers, are popular for their portability. In the foldable electronic device, a cover is rotatably connected to a main body via a typical hinge assembly.

The typical hinge assembly often includes a shaft, a rotary bracket, a fixed bracket, a cam, a cam follower, a plurality of friction members, and a resilient member. The rotary bracket, the fixed bracket, the cam, the cam follower, the friction members, and the resilient member are sleeved on the shaft. The cam forms two peaks, and the cam follower defines two valleys for engaging with the peaks. The cam and the cam follower resist each other caused by forces of the resilient member. When the peaks of the cam engage in the valleys of the cam follower, the rotary bracket is positioned at desired positions relative to the fixed bracket.

However, the cam and the cam follower are usually made of powder metallurgy alloy steels having high rigidity and made by injecting powder metallurgy alloy. The material and injecting process are costly. Thus, the hinge assembly has a relatively high cost.

Therefore, a new hinge assembly is desired to overcome the above-described shortcomings.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present hinge assembly may be used in foldable electronic devices, such as notebook computers, cell phones, media players, and so on. Referring toFIG. 1, an embodiment of a hinge assembly100includes a first leaf11, a second leaf12, a pivot shaft13, a tab washer14, a rotatable joint15, a positioning member16, an elastic engaging member17, a friction member18, and a fastening member19. In the illustrated embodiment, there are four positioning members16, four engaging members17, and two friction members18. The first and second fixing brackets11,12are non-rotatably sleeved on the shaft13, and the rotatable joint15is rotatably sleeved on the shaft13.

The first leaf11includes a mounting portion112and a joint portion114substantially perpendicularly formed from an edge of the mounting portion112. The mounting portion112and the connecting portion114are substantially flat pieces. The mounting portion112defines a fixing hole1122. The first leaf11may be fixed to a main body of an electronic device (not shown) such as by inserting a screw in the fixing hole1122and a threaded hole of the main body. The connecting portion114defines a non-circular engaging hole1142and a limiting arced slot1144sharing a center with the engaging hole1142. The connecting portion114further defines a first pinhole1146and a second pinhole1147.

The second leaf12includes a mounting portion122and a connecting portion124substantially perpendicularly formed from an edge of the mounting portion122. The mounting portion122and the connecting portion124are substantially flat pieces. The mounting portion122defines a fixing hole1222. The second leaf12may be fixed to the main body such as by inserting a screw in the fixing hole1222and engaging the screw with a threaded hole of the main body. The connecting portion124defines a non-circular engaging hole1242corresponding to the engaging hole1142of the first leaf11. The connecting portion124further defines a third pinhole1244and a fourth pinhole1245. The hinge assembly100further includes a first pin1148engaging in the first pinhole1146and the third pinhole1245, and a second pin1246engaging in the second pinhole1147and the fourth pinhole124, thus fixedly connecting the first leaf11and second leaf12.

The shaft13includes a cap132and a shaft portion134. The cap132is formed at an end of the shaft portion134and has a diameter larger than a diameter of the shaft portion134. The shaft portion134may be a non-circular column having a cross-section corresponding to a shape of the engaging holes1142,1242. The shaft portion134has two flattened surfaces1342. The shaft portion134further forms a screw thread1344at an end opposite to the cap132.

The tab washer14is approximately ring shaped. The tab washer14includes a ring portion141, a first bent tab144, and a second bent tab145. The first bent tab144and the second bent tab145are substantially perpendicularly and symmetrically formed from a periphery of the ring portion141, and extending in opposite directions. The ring portion141defines a central hole142and a plurality of oil holes146surrounding the central hole142.

The rotatable joint15includes a fixing portion152and a connecting portion154. The connecting portion154is substantially cylindrical and formed at an end of the fixing portion152. The fixing portion152defines a plurality of assembling holes1522. The rotatable joint15may be fixed to a cover of the electronic device such as by inserting a screw in each assembling hole1522and engaging the screw with threaded holes of the cover. The fixing portion152defines a substantially semi-cylindrical receiving groove1524aligned coaxially with the connecting portion154. The fixing portion152further defines a latching slot1526in a sidewall defining the receiving groove1524. The connecting portion154defines a through hole1542extending along an axis of the connecting portion154and a blocking slot1544in an end.

The positioning member16may be a substantially ring-shaped friction member having good wear resistance. The positioning member16defines a central hole162in a center portion. The positioning member includes an engaging surface164. An engaging protrusion1642may be formed on the engaging surface164, and a plurality of oil holes1644are defined on the engaging surface164between the engaging protrusions1642. In the illustrated embodiment, there are two engaging protrusions1642symmetrically formed on the engaging surface164. The positioning member16forms a blocking protrusion166at a periphery.

The engaging member17may be a substantially disk-shaped elastic member defining an engaging hole172. The engaging hole172has a shape corresponding to that of the engaging holes1142,1242. The engaging member17includes an engaging surface174engaging with the engaging surface162of the positioning member16. An engaging slot1742is defined in the engaging surface174. In the illustrated embodiment, there are two engaging slots1742symmetrically defined in the engaging surface174.

The friction member18is substantially ring-shaped and defines an engaging hole182in a center portion. The engaging hole182has a shape corresponding to that of the engaging holes1142,1242. The fastening member19may be a nut defining a threaded hole192. The fastening member19has a friction portion194formed at an end.

Also referring toFIG. 3andFIG. 4, the shaft portion134of the shaft13is passed through the engaging hole1242of the second leaf12, the engaging hole1142of the first leaf11, the central hole142of the tab washer14, the extending hole1542of the rotatable joint15, one positioning member16, two engaging members17, two positioning members16, two engaging members17, one positioning member16, and the friction members18, in that order. The fastening member19is screwed on the screw thread1344of the shaft13. The positioning members16and the engaging members17are positioned in pairs, i.e., each positioning member16is positioned to engage with one corresponding engaging member17. The positioning members16, the engaging members17and the friction members18are received in the receiving groove1524of the rotatable joint15. The blocking protrusions166of the positioning members16are non-rotatably and slidably engaged in the latching slot1526of the rotatable joint15. The engaging surfaces164of the positioning members16are engaged with the engaging surfaces174of the engaging members17. The first and second bent tabs144,145are engaged in the limiting arced slot1144of the first leaf11and the blocking slot1544. The first leaf11, the second leaf12, the shaft13, the engaging members17, the friction members18, and the fastening member19are non-rotatable relative to each other, but rotatable relative to the rotatable joint15, the tab washer14, and the positioning members16. The first and second pins1148,1246may be riveted to connect the first leaf11and the second leaf12.

When the cover is folded over the main body of the electronic device, the hinge assembly100is in a first state. In the first state, the engaging member17resists the positioning members16, and the engaging slot1742engages with the engaging protrusion1642of the corresponding positioning member16. The rotatable joint15is positioned in a first position relative to the first leaf11and the second leaf12. When the rotatable joint15rotates relative to the first leaf11and the second leaf12, the tab washer14and the engaging members17rotate together with the rotatable joint15. The positioning members16continue to resist the engaging members17as the rotatable joint15rotates, and the first bent tab144of the tab washer14slides into the limiting arced slot1144of the first leaf11. As the rotatable joint15rotates further, the engaging protrusions1642of the positioning members16slide out of the engaging slots1742of the engaging members17and deform the engaging members17. A friction force is generated between the components of the hinge assembly100. Thus, the rotatable joint15can be held at any position relative to the first leaf11and the second leaf12. The limiting arced slot1144of the first leaf11restricts an amount that the rotatable joint15and the first leaf11and the second leaf12can rotate relative to each other. When the first bent tab144reaches an ultimate position of the limiting arced slot1144, the rotatable joint15is prevented from rotating further and the rotatable joint15reaches a maximum opening position. A friction force between the components of the hinge assembly100may be adjusted by adjusting the fastening member19inwards or outwards.

The hinge assembly100does not employ any cam or cam follower which have high costs. The hinge assembly100can perform the positioning function with the engaging protrusions1642of the positioning members16and the engaging slots1742of the engaging members17. The positioning members16and the engaging members17can be manufactured by a pressing method which is inexpensive. Therefore, the hinge assembly100has low cost. Alternatively, the second leaf12of the hinge assembly100may be omitted, furthering lowering material and assembly.