Cam adjustment device for lifting and lowering armrest and chair having the same

A cam adjustment device for lifting and lowering an armrest, comprising an armrest assembly and a support frame configured to support the armrest assembly,

• wherein the armrest assembly comprises a connection base, the support frame has a support rod arranged in a longitudinal direction, the connection base is slidably connected to the support rod, a locking mechanism is provided between the connection base and the support rod,
• the locking mechanism comprises a cam wrench disposed on the connection base, the cam wrench is rotatably installed on the connection base, the cam wrench is rotated such that a cam on the cam wrench directly or indirectly presses and acts on the support rod,
• the armrest assembly has a locked state and an unlocked state, in the locked state, the cam wrench presses and acts on the support rod such that the connection base and the support rod are kept to be relatively fixed, and in the unlocked state, the cam wrench is rotated to allow the cam to be released from the support rod, such that the connection base is lifted, lowered, and adjusted relative to the support rod.