In mechanical clocks, the energy released by the recovery of deformation with a spring (spring) or the force of gravity falling from a heavy object is used as the time reference to realize the mechanical mechanism of measuring time and screw. Type, but generally consists of the drive train, drive train, escapement longitudinal speed control system, winding needle system and pointer system, the working principle is basically the same. In addition, the calendar watch also includes a calendar (or double calendar) mechanism, and the automatic watch also includes an automatic winding mechanism.
The original weight is a mechanism that stores and transfers working energy. Divided into two types of heavy hammer prime mover and spring prime mover.
Weight Drive System
The structure of the weight drive system is simple and the inductance is stable. However, when the weight is raised, the drive train is disconnected from the drive system and the clock mechanism stops working.
Spring Motive System
The spring motive system uses the energy released by the spiral coil spring (spring) to recover the deformation. The spring end is connected to the shaft, and the other end is connected to a stationary part or the shell of the barrel. The original line has 3 types: fixed box type, non-box type and movable box type.
Drive Train Transmits
The drive train transmits the energy of the drive train to a set of drive gears of the escapement longitudinal speed train. Usually consists of gear wheels and gear shafts (Figure 3). In the main drive, the gear wheels are driving gears, and the gear shafts are driven gears. The transmission ratio is calculated according to the following formula: i = Z1 / Z2 where Z1 is the number of driving gear teeth and Z2 is the number of driven gear teeth. For a clock with a second hand device, the transmission ratio between the disk of the center wheel and the pinion of the second wheel must be equal to 60. The tooth profile of the horological drive train must be specially designed.
The power train can be divided into two types according to the “two wheels” (time wheel and minute wheel) in the plane configuration of the watch movement: ① central two-wheel type, the second wheel is in the center of the watch movement. It also includes direct drive, second spring, short second and non-second hand, double triple wheel. ② Partial two-wheel type, the second wheel is not in the center of the watch movement. It also includes the first round out, the second round out, and the three round out.
In this transmission mode, the friction above the minute wheel cooperates with the central wheel tube; the movement of the needle moving mechanism is driven by the central wheel.
Escapement Speed Control System
The escapement speed control system consists of an escapement mechanism and a vibration system. According to the characteristics of the vibration system, it can be divided into two categories: ① Escapement longitudinal speed control system with inherent vibration period. It has the ability to vibrate independently and has a stable periodic vibration system. . The escapement speed control of the travel time system in watches and alarm clocks belongs to this category. ② Escapement speed control system without inherent vibration period. It does not have a vibration system capable of independently vibrating. This speed control system is called a vibration system. The escapement speed regulation of the alarm system in mechanical alarm clocks belongs to this category. This type of speed regulation system requires low accuracy, simple structure, reliable operation, and strong anti-interference ability. It is widely used in mechanical timers and clock fuze.
A mechanism that connects the drive train and the vibration system. Its function is to transfer the energy of the prime mover to the vibration system to maintain the constant amplitude vibration of the vibration system; and to transmit the vibration frequency of the vibration system to the pointer mechanism to achieve the purpose of measuring time. There are many types of escapement, which can be divided into two types according to the degree of connection with the vibration system. ①Non-free escapement: The escapement and the vibration system often maintain a kinematic connection. It includes a straight-forward ② free-style escapement: only in the release and transfer stages, the escapement mechanism and the vibration system maintain a kinematic connection, and the vibration system is in free movement in the other stages. It includes pin type, fork type and astronomical clock escapement.
① Retreat escapement:
widely used in low-precision pendulum clocks. The locking surface and the punching surface of the fork shoes are the same plane (working surface); the working surface of the incoming tile is a cylindrical surface, and its center does not coincide with the rotation center of the pallet; the working surface of the outgoing tile is a plane. The fork shoe and the pallet fork are integrated. After passing the charge, the fork shoe working surface will back the escapement wheel by an angle.
② Fork escapement:
one of the most widely used escapement. During work, the escapement wheel obtains energy from the drive train, and through the action of escapement gear teeth and fork shoes (into or out of the tile) into the impulse transfer to the escape fork; through the fork of the escape fork and the dual disc The interaction of the pendulum on the impact disk transmits the impulse to the vibration system. The double-disk safety disc and fork stud, the swing pin and the bell mouth of the pallet fork are safety devices to ensure the normal operation of the mechanism.
③ Pin-type escapement:
The difference from the fork-tile escapement is that two cylindrical pins are used instead of the fork on the escapement fork, and the impulse is transmitted only along the escape surface of the escapement tooth. This escapement has a simple structure, low accuracy requirements, and convenient manufacturing. It is mostly used in alarm clocks and low-precision meters and is commonly called a rough horse structure. Vibration system as a time reference mechanism. The vibration period of the vibration system is multiplied by the number of vibrations inside the measured process, which is the time elapsed by the process. Vibration systems commonly used in mechanical clocks are pendulum, torsion pendulum and balance spring vibration systems.