Motor Hammer Impact Control via Magnetic Ram Actuation
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Solution Overview
Problem
Existing motor-driven hammers can only change the power of impact by varying the rotational speed of the motor, which is limiting when used in drill mode where rotational speed is constant.
Innovation Solution
Incorporating a coil adjacent to a paramagnetic or ferromagnetic ram within the hammer's housing, allowing the ram's movement to be influenced by an external magnetic field, enabling selective control of the power of impact without altering the motor's rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotational speed of the motor is varied to change the power of impact, then the power of impact can be adjusted, but the motor speed must change which limits performance in drill mode where constant speed is required
Solution Approach 1:
The patent replaces the purely mechanical speed-dependent impact generation with a hybrid system that uses electromagnetic force (coil acting on paramagnetic/ferromagnetic ram) to supplement or enhance the impact power. This allows impact power adjustment without requiring motor speed changes, resolving the contradiction between adjustable impact power and constant motor speed requirement in drill mode
Solution Approach 2:
The patent changes the physical state or properties of the ram by using paramagnetic or ferromagnetic materials, enabling it to respond to magnetic fields from the coil. This parameter change allows the ram's movement and impact power to be controlled independently of motor speed, particularly enhancing performance at low rotational speeds where electromagnetic assistance is most beneficial
2Use of energy by moving object
If the motor runs at low speed to reduce energy consumption, then energy efficiency improves, but the power of impact becomes relatively low
Solution Approach 1:
The electromagnetic coil system provides an alternative mechanism for generating impact force that is not dependent on motor speed. When the motor runs at low speed, the coil can be activated to provide additional or primary impact force through magnetic attraction/repulsion on the ferromagnetic ram, maintaining adequate impact power while consuming less energy
Solution Approach 2:
The ram is made of composite or specialized material (paramagnetic or ferromagnetic material) that enables it to interact with the electromagnetic field. This material property allows the ram to be accelerated or decelerated by the coil's magnetic field, providing impact power enhancement independent of motor speed and enabling low-energy operation with sufficient impact power
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables adjustable power of impact without changing the motor's speed, enhancing performance in drill mode by selectively accelerating or decelerating the ram using the magnetic field, thereby increasing overall impact power, especially at low rotational speeds.
Implementation Method 1
the coil applies a force in the direction of the longitudinal axis on the ram if a current is applied to the coil
Implementation Method 2
the ram is made of a paramagnetic or ferromagnetic material
Implementation Method 3
the coil applies a force in the direction of the longitudinal axis on the ram
Data Source
Figure 1
AI summary
A motor driven hammer is described comprising a housing (3), a motor (9) having a motor shaft (11) and being arranged in the housing (3), a hammer mechanism including a cylinder (17) in which a ram (23) is arranged the ram being slidable along a longitudinal axis (L) of the cylinder (17), and a tool holder (15) which may support a tool bit so that the tool bit is aligned with the longitudinal axis (L) of the cylinder (17), wherein the motor (9) is coupled with the hammer mechanism, so that rotation of the motor shaft (11) results in a reciprocating movement of the ram (23) within the cylinder (17), the ram (23) applying impacts on a tool bit supported by the tool holder (15) during the reciprocating movement. Further, the ram (23) is made of a paramagnetic or ferromagnetic material or comprises a permanent magnet and a coil (47) is arranged within the housing (3) adjacent to the cylinder (17) so that the coil (37) applies a force in the direction of the longitudinal axis (L) on the ram (23) if a current is applied to the coil (47).