How the Brushless Screwdriver Motor Works
It is difficult to imagine an arsenal of a home master without a screwdriver. This tool is able to replace screwdrivers, wrenches and drills. Structurally, it consists of two main parts. Electrical and mechanical, through which useful work is performed. Many owners do not know all its capabilities, and even more so how a screwdriver works. It is a question of the principle of operation that needs to be examined in detail in order not only to evaluate the capabilities of the device, but also to facilitate the repair.
How is a screwdriver or device design
The considered type of tool works on the principle of converting electrical energy into mechanical energy, thereby doing useful work. Based on this, screwdrivers are classified into mains and cordless. Cordless models are popular due to their portability, but networked models also have an advantage. This is high power compared to battery ones. Network screwdrivers are also called drills, as they can not only screw fasteners, but also drill wood and metal.
The external device of the network and battery models is almost identical, with the exception of a slight difference. This difference lies in the presence of a battery on portable tools, as well as the presence of a wire for connecting to an outlet on network-type devices. The internal device has more differences, however, the principle of operation of power and battery type screwdrivers is the same. The main structural elements of the considered devices are:
- High impact plastic housing
- Chuck (usually keyless)
- Button, switch or trigger for starting the tool
- The switch modes of the direction of movement of the executive body. Reverse
- Speed controller in the form of a switch
- Torque regulator. Better known as ratchet
To understand the device, below is a photo with a description of each element. The operation of the device is based on the following details, which are inside the case:
- Collector or brushless type electric motor
- Gear mechanism in the form of a planetary gear
- Safety clutch with a force regulator. Eliminates jamming and overheating of the motor, thereby preventing its failure
Depending on the model of the instrument, they can also be additionally equipped with a backlight, battery indication or LED display. The housing design may have grooves for accommodating interchangeable bits, which facilitates the operation of the device.
The principle of the screwdriver from A to Z understand how the tool works
The battery-powered models are popular, therefore, using their example, we will analyze the principle of the work of screwdrivers. Knowing the device and the design of the screwdriver, it will not be difficult to find out how this device works. However, often even experienced craftsmen stumble when answering questions. Why a rattle is needed, how the button works, and why planetary gearboxes are used on screwdrivers, and not ordinary ones. Consider the detailed principle of the screwdriver, and find out all the answers.
- The device starts to work when you press a button, which is also called a switch. However, switches (do not have the option of speed control) are usually used on angle grinders, and buttons with an integrated speed controller are used on screwdrivers. The principle of operation of the regulator is simple. The stronger the pull force on the trigger, the higher the rotation speed of the cartridge
- In order for the cartridge to rotate when the start button is pressed, it is necessary to supply direct current to the electric motor. For this, a battery is used, which acts as source. It consists of a set of cans that are connected in series, which together allows you to get voltage from 9 to 24V
- The battery on the screwdrivers is removable, which allows not only recharging it, but also changing it when discharging. From the battery, current is supplied to the power button. If the battery is discharged or damaged, the screwdriver can operate on a car battery.
- The button has a complex design of a non-separable type. The button closes the contacts, and also changes the polarity of the voltage supplied to the contacts of the electric motor
- Two wires from the battery are connected to the button, which are closed and go to the contacts of the DC collector motor. In the design of the button there is an element that is responsible for adjusting the rotation of the cartridge depending on the force of pulling the trigger. The so-called soft start
- A direct current is supplied to the collector motor, which is supplied to the rotor winding. The role of the stator in the engine is performed by permanent magnets, through which the rotor rotates. A gear is attached to the rotor shaft, the torque from which is transmitted to the gearbox
- The planetary gear type on a screwdriver consists of a set of gears with internal and external links. By means of gears, torque is transmitted from the engine to the tool holder
- The gearbox is connected to the shaft on which the cartridge is mounted. A working nozzle is fixed in the jaws of the collet device. A drill, a bit and others
- In addition to these elements, the design of the screwdriver has a ratchet or clamp force regulator with a safety clutch
- The safety coupling eliminates the possibility of jamming of the shaft, for example, when drilling or screwing a screw. The absence of a safety clutch contributes to the fact that the rotor winding can burn out due to an increase in load
- The torque force regulator serves to provide an effective impact on the machined surface. It eliminates the rotation of the cartridge relative to the shaft, eliminating the increase in load. The presence of a regulator allows you to screw fasteners with a certain moment
All these devices are components of a screwdriver. Let us consider in detail each element of the tool, as well as its design features, which will help to understand the question of how a screwdriver works. The below shows a detailed working principle of a drill / driver.
How the battery works on standalone screwdrivers
The battery is the source through which the electric motor is driven. The design of the battery uses cylindrical cans of nickel-cadmium or lithium-ion filling (there are also metal hydride). Each bank gives a voltage of 1.5 to 4 volts, which depends on the type of filling. Each bank is connected among themselves in series, therefore, as a result, the voltage of each bank is summed up. This voltage is transmitted through the contacts to the instrument.
Depending on the number of cans inside the screwdriver’s battery, the batteries are capable of delivering voltages from 9 to 24V. The most popular are models on 12V-14V. 9-volt screwdrivers are low-power, and devices with a supply voltage from 18V to 24V belong to high-power. In addition to voltage, batteries have another important parameter. This is capacity. Capacity is the amount of charge that a battery can deliver in a given amount of time. The larger the capacity, the longer the screwdriver is able to work without recharging. To charge the battery, special chargers are used, the principle of operation of which must be considered.
How the charger works and its circuit
The charger for the screwdriver is a block with a microcircuit, a network wire and output contacts. The principle of operation of a charging screwdriver is as follows:
- The power supply voltage is applied to the unit
- In the block, the conversion of alternating voltage to constant occurs. Achieved through the use of a rectifier bridge
- In addition to voltage conversion, it also decreases to the corresponding level of 9. 24v. Implemented by a transformer or inverter
- The ability to recharge a battery with a charger is based on the magnitude of the output current
- Not only the ability to recharge the battery, but also the duration of charging depends on the current value.
The charging operation diagram is shown in the photo below.
Having an idea of how the charger works on a screwdriver, it will not be difficult to repair it.
Screwdriver button operating principle and design
Battery voltage is supplied to the engine through a button. The button is used not only as a device for closing contacts.
The following tasks are assigned to the button:
- Closing the contacts of the wires “plus” and “minus”, due to which power is supplied to the engine
- Reverse. A change in the polarity of the contacts of the wires entering the engine. This allows rotation of the motor shaft in different directions.
- Speed adjustment depending on the force of pressing the start button
The task of the button is to provide a smooth supply of voltage to the tool’s engine when the trigger is pulled.
How the Brushless Screwdriver Motor Works
The engine on the screwdriver and how it works
The principle of operation of the collector and brushless (brushless) motors are different. The most popular on screwdrivers are collector type motors. Their advantage is low cost, and the disadvantage of having a consumable item is brushes. Over time, during operation of the device, the brushes wear out, so at one point you can find that the motor stops working. Often such a breakdown by the owner of the tool is perceived as the burning of the rotor winding, but it is enough to replace the brushes or clean (usually copper) so that the device resumes its work. Graphite or carbon brushes are used on power tools.
In the collector motor, current is supplied to the rotor winding through the brush assembly. When the current flows, an electromotive force is induced, thereby turning the rotor from the winding into a magnet. Around the rotor is a stator in the form of two magnet plates. The counteraction of two magnets (rotor and stator) contribute to the repulsive force, which ultimately leads to the fact that the rotor begins to rotate. The rotation force is used for useful purposes to set the tool holder with working nozzles in motion. This is how all collector motors work, both mains and battery type. The only difference between them is that on network devices, the motor consists of a stator and a rotor with windings.
The principle of operation of a brushless motor is characterized in that the shaft is connected to the stator. The stator consists of magnets and is driven. At the same time, the rotor stands still, and current is directly supplied to it without brushes. Emf is induced in the winding of the rotor, and now through the reaction force the rotation of the movable element. The stator. The brushless motor is more reliable and efficient, since there are no consumables (brushes) in it, which means that it is able to work long enough until the winding burns out. They have a drawback. This is a high cost. Below is a diagram of how a brushless motor works on a screwdriver.
The high cost of brushless motor screwdrivers lies in the complexity of their device. To ensure the rotation of the stator from magnets, not two, but three wires should be connected to the rotor winding. This is necessary to ensure the phase-shifting effect by which the EMF is induced. To achieve this effect, special devices are used that provide voltage with phase shift.
How a screwdriver gear works
The planetary gear mechanism is designed to reduce the speed of rotation and increase the force of the moment. The gearbox consists of a set of gears. They have a different number of teeth, due to which there is a decrease in the rotation speed to the corresponding values.
The design of screwdrivers has switches designed to operate the tool at different speeds:
- The first is slow, used for screwing screws, screws, and also threaded connections
- The second is fast, when you turn on the tool in mode “2”, the cartridge rotates at a speed 2 times faster than at 1 speed. In this mode, the device is used for drilling metal and wood. Concrete can be drilled with a screwdriver only if it has a shock mode. Typically, these are high-power, network-type impact drills and drills
The gearbox consists of leading and driven links. Gears. Leading gears are called the “sun”, and driven by the “carrier”. Speed adjustment is due to the mechanical switching of gears with a large number of teeth to small. As a result, the tool is able to work in two modes. Drilling and screwing.
How the ratchet mechanism works on a screwdriver
In addition to the gear mechanism, a device such as a torque regulator with a safety clutch is also used in the design of the tool. These two devices are interconnected, but have a similar design. First, find out why you need a rattle and a mechanism for adjusting the torque, which is not available on drills and screwdrivers.
The screwdriver is designed to perform screwing of self-tapping screws and other fasteners. When screwing screws into the wood, a different force is required, which depends on the length of the fastener, as well as the type of wood (hardness).
This requires effort with varying degrees of strength. The design has a mechanism, which is called a rattle. The principle of operation of this mechanism is similar to a torque key. Upon reaching the corresponding effort, which is set manually, the handle is rotated relative to the key head. Consider what this mechanism is on a screwdriver:
- One large spring or a set of springs, due to which the clamping force is regulated
- Nipples or cams that are used to connect to the gear mechanism. Balls from bearings are also used as fittings. On the example of the photo below, the protrusions are placed on the plate
- Grooves or grooves through which the fitting is connected to the spring acting on it
For ease of perception, on the outside of the device there are designations in the form of numbers from 1 to 24 or more. The more numbers on the body of the force regulator, the higher the tuning range. The stronger the spring acts on the fitting, the greater the clamping force. Switching the regulator to the high value mode allows screwing long self-tapping screws into hardwood.
The clamp force regulator simultaneously performs a protective function, due to which the probability of stator jamming is eliminated. If the nozzle is fixed, which is fixed in the tool holder, then the fittings slip through the grooves in the regulator. The rotor overcomes the force, but does not jam. The absence of such a mechanism would lead to burnout of the rotor windings, due to an increase in current.
In order to protect the engine of the tool from its combustion, the friction-type safety clutch is also used in the design. Below it is presented in the photo, and it works when the nozzle is jammed. For example, the maximum force on the regulator is set, in which case, if the drill gets stuck, it is highly likely that the device will be pulled out of the hands. To avoid this, a protective sleeve is used that eliminates the tearing of the instrument from the hands and also prevents the winding from burning on the rotor.
When the nozzle is jammed in the cartridge, the engine rotor stops. To prevent such jamming, a safety clutch is also used in the design for this. It works only in one mode, when the actuator rotates in the right direction. When the cartridge rotates to the left, the coupling does not work, as can be seen in the photo above. Usually, additional safety couplings are used on powerful screwdrivers from 14V. Below in the photo there is a variation of the screw clamp force regulator, the principle of operation of which is similar to the description.
The principle of operation of the cartridge
Chucks on screwdrivers come in two types. Keyless and keyless. Keyless keys are more popular, and they are one and two-coupling. The key ones are more reliable, since they exclude the possibility of turning the nozzle. Key executive bodies are usually used on drills, which exclude turning drill with cylindrical shanks. Screwdrivers usually use quick-clamping tools, since they reliably fix bits in the form of bits having a hexagonal shank design.
Key and quick-clamping chucks on screwdrivers have a similar design and operating principle, which is based on the movement of the clamping jaws. The design has three jaws, which fix the shanks of the working nozzles. Drills, bits, polishing nozzles and more.
In order for the cartridge to serve for a long time, it is necessary to periodically introduce lubricants inside, as well as clean the working bodies from clogging. If the jaws fail, they cannot be replaced. When choosing a cartridge, it must be borne in mind that they differ in such a parameter as the diameter of the nozzle shanks that can be fixed in it. It is necessary to take into account the diameter of the hole for mounting on a screwdriver.
The chuck is attached to the screwdriver with two threaded clamps. The first clamp is inside, and is presented in the form of a tetrahedral (rarely single-sided) screw, which has a left-hand thread. To unscrew it, you need to twist to the right side. After unscrewing the screw, it is necessary to unscrew the element itself, which is mounted on the shaft.
The principle of the screwdriver is simple and straightforward, but everyone who plans to repair it, remodel, modernize, etc., should deal with it. Knowing the principle of the screwdriver and wrench, you can eliminate any damage to these devices, and return the tool to working condition.
How to work with a screwdriver instruction
Before working with a screwdriver, you need to study the instructions and its purpose. Devices differ in power, which indicates their abilities. The instructions indicate the operational capabilities of the unit. Screwdrivers from the network are more powerful, so they can be used to perform various tasks, and even for drilling concrete.
If you bought a screwdriver, then you need to learn how to use it first. This will allow not only to perform quality work with a screwdriver, but also to eliminate the likelihood of its rapid failure. So, we will consider the features of using a screwdriver, which will allow us to learn how to work correctly.
- For drilling bricks and concrete. Concrete or brick cannot be drilled with a conventional screwdriver. To do this, the tool design must have a built-in option for drilling with impact, and if there is none, then the device is simply useless. It is not difficult to fix a drill with a win in the chuck, but when exposed to concrete or brick, it will simply fidget, since there is no shock option. For such purposes, impact drills or perforators are used.
- For drilling wood. To drill a hole in a tree with a screwdriver, you must use special drills with a lance at the end. The maximum drilling diameter of a wood screwdriver is 20 mm. It all depends on the power of the device. When drilling, the drill must be held strictly at an angle of 90 degrees with respect to the surface to be drilled.
- For metal drilling. Special drills are also used for this. The quality of drilling depends on the edge sharpening. Drill metal with a screwdriver up to 10 mm. When performing work, you must consider how to use a screwdriver. First you need to use a core to make a recess along which the drill will be guided. To avoid overheating of the cutting edge of the drill, lubricate the nozzle with a special compound or water during operation. It should be borne in mind that water must be supplied during the drilling process, and not after. If you lower the hot drill into water, then it will lose its strength properties, and it will quickly become dull. The drill must also be held strictly at an angle of 90 degrees with respect to the surface being machined in order to avoid jamming of the nozzle or its breakage
- Screw tightening. For this, a bit or adapter for bits is attached to the cartridge. The fasteners should be twisted and unscrewed at the first speed, which will prevent breakage of not only the tool, but also the bit. It is absolutely necessary to select the correct bits, depending on the type of construction of the fastener cap. The edges of the bits must fit tightly into the grooves of the fastener, otherwise in the process they will slip and erase the edges of the fastener
If the puncher and drill are purely male tools, then even a woman can work with a screwdriver, for example, when you need to tighten a screw or a screw on a shelf. Before using the tool, check the battery charge. Then it is necessary to fix the working nozzle in the cartridge, and proceed to work. A detailed description of how to operate the screwdriver correctly is described in the material.
Features of proper storage in order to increase service life
Knowing how the power and battery type screwdrivers work, it remains to understand the question of how to care for them in order to extend the service life. Everything is as simple as the working principle of a screwdriver. During storage, the following recommendations are taken into account:
- Prevent water from entering the tool
- Do not miss or drop the device, as in addition to damage to the case, internal devices may fail
- Regularly lubricate the cartridge to increase its life
- If various contaminants get inside, then before the subsequent use of the device, it should be disassembled and cleaned.
- Do not store the tool with fully discharged batteries
- Store and operate the device in a temperature range of at least 5 and no more than 30 degrees
- When drilling, cool the nozzle
Only if all the above recommendations are observed, it is possible to ensure continuous use of the tool without breakdowns. The service life of the device also depends on quality, since a cheap Chinese screwdriver will not be able to serve a priori for a long time, because in its production exclusively low quality components are used.
To summarize, it is worth noting that not only the master, whose work is associated with the operation of the device, but also beginners who use the tool for the first time should know how a screwdriver works. This will extend the life of the screwdriver, and also eliminate the need to take the device to a service center in case of malfunctions.