Abstract: A contact head unit provided in a contact apparatus may be provided with a contact rod, a housing, a thrust air passage, and a cancel air passage. The housing supports the contact rod linearly movably by a static pressure air bearing, which allows the contact rod to be brought into contact with an object. If a compressed air is supplied to the thrust air passage, a force in a direction of approaching the object acts on the contact rod. If the compressed air is supplied to the cancel air passage, a force in an opposite direction acts on the contact rod. A control unit sets applied pressure on the object by controlling the pressure of the compressed air of the thrust air passage and the pressure of the compressed air of the cancel air passage while the contact rod is in contact with the object.

Abstract: A power tool that includes a driving motor and a power transmitting mechanism. The power transmitting mechanism includes a first clutch cam part, a second clutch cam part, clutch teeth, a clutch detecting mechanism and a controller that can control the driving motor in a first control mode in which the driving motor is controlled to rotate at a first rotation speed until before the first and second clutch cam parts are engaged with each other at the clutch teeth and in a second control mode in which the driving motor is controlled to rotate at a second rotation speed higher than the first rotation speed after the first and second clutch cam parts are engaged with each other at the clutch teeth.

Abstract: An orthopedic impacting tool comprises a motor, an energy storage chamber, a striker, and an anvil. The motor stores energy in the energy storage chamber and then releases it, causing the striker to apply a controlled force on an adapter to create a precise impact for use in a surgical setting. The tool may further comprise a combination anvil and adapter. An energy adjustment control of the tool allows a surgeon to increase or decrease the impact energy. A light source and hand grips improve ease of operation of the tool.

Abstract: An orthopedic impacting tool comprises a motor, an energy storage arrangement, a striker, and an anvil. The motor stores energy in the energy arrangement means and then releases it, causing the striker to apply a controlled force on an adapter to create a precise impact for use in a surgical setting. The tool may further comprise a combination anvil and adapter. The tool further allows forward or backward impacting for expanding the size or volume of the opening or for facilitating removal of a broach, implant, or other surgical implement from the opening. An energy adjustment control of the tool allows a surgeon to increase or decrease the impact energy. A light source and hand grips improve ease of operation of the tool.

Abstract: A screwdriving tool that includes a driving tool (driver), a sensor, a sensor target and a contact trip assembly that is coupled to the driving tool and has a nose element. The driver has a housing, a motor and an output member that is driven by the motor. One of the nose element and the output member is axially movable and biased by a spring into an extended position. The sensor and sensor target are configured to cooperate to permit the sensor to provide a sensor signal that is indicative of movement of the one of the nose element and the output member. The motor is controllable in a first operational mode and at least one rotational direction based in part on the sensor signal.

Abstract: One embodiment includes display device configured to wirelessly receive a first position status from a positioning device; display a first work-tool working-axis leveling status based on the first position status; receive cut parameters; receive a cut-start indication; determine a first work-tool position status difference based on cut parameters and a second position status; present a position status correction indicator; determine that a third position status is within cut parameters; send a cut-start signal to the positioning device operable to actuate the first work-tool; determine a work-tool cut completion; and send a cut-end signal to the positioning device operable to de-actuate the first work-tool.

Abstract: An oil pulse tool includes a motor, an oil pulse unit, an output shaft on which a front end tool is attached, a torque detecting sensor for detecting generation of an impact torque, and an operating portion configured to detect a time period between a first impact torque detected by the torque detecting sensor and a second impact torque detected by the torque detecting sensor. The second impact torque is smaller than the first impact torque. The operating portion carries out a notification when the time period between the first impact torque and the second impact torque is less than a predetermined evaluation value for the time period between the first impact torque and the second impact torque.

Abstract: An impact tool includes a motor, a hammer, an anvil, and a control unit. The hammer is configured to be driven by the motor and be movable in an axial direction of the motor. The anvil is configured to be struck by the hammer. The control unit is configured to control a rotation of the motor. The impact tool further includes a restricting unit configured to restrict the movement of the hammer in the axial direction. The control unit is configured to select a driving mode of the motor between a first mode and a second mode. The control unit selects the first mode when a load of the motor is less than or equal to a prescribed value regardless of a restriction of the restricting unit, whereas the control unit selects the second mode when the load exceeds the prescribe value and the restricting unit restricts the movement of the hammer.

Abstract: A power tool has a continuously variable transmission, a condition detection device, and an operation control device. The continuously variable transmission changes a velocity of a rotational output from a drive motor and outputs the rotational output to a spindle to which a tip end tool is mounted. The condition detection device detects a condition of the power tool. The operation control device determines a target RPM of the spindle based on the condition of the power tool detected by the condition detection device, and controls an RPM of the drive motor and/or a transmission gear ratio of the continuously variable transmission based on the target RPM.

Abstract: A method is provided for controlling operation of a power tool, such as a drill driver. The method begins with one or more descriptors for a fastening application being received by a controller residing in the power tool, where the descriptors are indicative of a fastening application to be performed by the power tool and are received via a wireless data link from a computing device located remotely from the power tool. The descriptors are translated into a threshold value used by a fastener setting algorithm and the threshold value is stored in a data store of the power tool. During a subsequent fastening operation performed using the tool, an operating parameter of the power tool is monitored and evaluated in accordance with the fastener setting algorithm, including the updated threshold value. Example operating parameters include current delivered to the motor and speed of the motor.

Abstract: A screwdriving tool that includes a driving tool (driver), a sensor, a sensor target and a contact trip assembly that is coupled to the driving tool and has a nose element. The driver has a housing, a motor and an output member that is driven by the motor. One of the nose element and the output member is axially movable and biased by a spring into an extended position. The sensor and sensor target are configured to cooperate to permit the sensor to provide a sensor signal that is indicative of movement of the one of the nose element and the output member. The motor is controllable in a first operational mode and at least one rotational direction based in part on the sensor signal.

Abstract: A hand tool operating unit includes at least one operating member, and an electronic operating unit that has a position sensor configured to ascertain a position of the operating member. The hand tool operating unit additionally includes at least one further sensor that is configured to ascertain at least one characteristic variable.

Abstract: An orthopedic impacting tool comprises a motor, an energy storage means, a striker, and an anvil. The motor stores energy in the energy storage means and then releases it, causing the striker to apply a controlled force on an adapter to create a precise impact for use in a surgical setting. The tool may further comprise a combination anvil and adapter. The tool further allows forward or backward impacting for expanding the size or volume of the opening or for facilitating removal of a broach, implant, or other surgical implement from the opening. An energy adjustment control of the tool allows a surgeon to increase or decrease the impact energy. A light source and hand grips improve ease of operation of the tool.

Abstract: A generator stator core through-bolt tensioning device that automatically tightens the nut on the through-bolts that hold together and compress laminate plates of the stator core in a high voltage generator. A controller receives a signal from a measuring device, such as a fiber Bragg grating that measures the strain on the bolt, and based on that signal determines whether the nut needs to be tightened. If the controller determines that tightening is necessary, it will cause the tensioning device to automatically tighten the nut while the generator is in service, and use the measuring device to provide feedback of the tensioning of the through-bolt to know when to stop the device from tightening the nut.

Abstract: A portable power wrench of an angle type includes an elongated housing with an angle drive head and a rear handle and supports a motor. The power wrench also includes a manually operated power control device including a main power control trigger located at the rear handle and an auxiliary power control trigger located at the angle drive head. The motor as well as the main trigger and the auxiliary power control trigger are connected to a programmable control unit in which there are stored operation parameter sets suitable for a screw joint running down phase and a final tightening phase, respectively. The auxiliary power control trigger is arranged to activate the running down parameter set only, whereas the main power control trigger is arranged to activate the final tightening parameter set.

Abstract: A system includes a power tool having a motor, a drive mechanism mechanically coupled to the motor, and an output element mechanically coupled to the drive mechanism. The motor is operable to drive the drive mechanism and the output element. The system also includes a non-motorized sensing tool having a printed circuit board and a sensing element electrically coupled to the printed circuit board. The sensing element is operable to detect an external characteristic and output a signal to the circuit board. The circuit board is operable to condition the signal into a human-comprehensible form. The system further includes a rechargeable battery pack removably and independently coupled to the power tool and the non-motorized sensing tool to power the motor to drive the drive mechanism and the output element when connected to the power tool and the circuit board and the sensing element when connected to the non-motorized sensing tool.

Abstract: A handheld power tool is configured to receive an input indicative of a clutch setting for an electronic clutch from the tool operator, where the clutch setting is selectable from a drill mode and a drive mode. In a drill mode, torque applied to the output spindle is ignored; whereas, in the drive mode, the torque applied to the output spindle is monitored and interrupted in an automated manner by a controller when a fastener being driven reaches a desired stopping position. Display states of the interface components of the tool may be set in accordance with current tool conditions and/or various triggering conditions. One such interface component is the input used to set the operating mode (e.g., clutch setting) of the tool.

Abstract: Driver assemblies, drivers, drill bits, and methods for determining information (such as impedances, voltages, voltage differences, and changes in such information) about biological material during a medical procedure.

Abstract: A control method for a power tool and a power tool is disclosed. The control method has an operating mode and a safety mode. In the operating mode, a motor drives a tool receptacle in a rotating manner. In the operating mode, the motor has a power consumption in the amount of at least an operating value. The safety mode is triggered if a sensor device detects a rotational blockade of the tool receptacle. In the safety mode, a clutch that is switchable by electrical signals located in the drive train between the motor and tool receptacle is periodically opened and closed and a power consumption of the motor is reduced as compared to the operating value.

Abstract: A battery-powered portable tool, such as a chainsaw, hedge trimmer or handheld drill, comprising: a housing (1), a driven element (2) supported by the housing (1), an electric motor (6) coupled to the driven element (2) so as to drive the driven element (2), a battery (5) electrically coupled to the motor (6) so as to supply electric current to the motor (6) and a control circuit (8) arranged to control the supply of electric current to the motor (6) from the battery (5), in which the control circuit (8) comprises a main switch (8) operable by a user and an auxiliary switch (10, 11) also operable by a user; in which the control circuit (8) has: an active state in which operation of the main switch (8) by the user allows electric current to flow to the motor (6) so as to cause the driven element (2) to be driven; and an inactive state in which operation of the main switch (8) does not allow electric current to flow to the motor (6) and so the motor (6) does not drive the driven element (2); in which operation

Abstract: A pneumatic impulse wrench for tightening screw joints includes a housing with a pressure air inlet passage, an exhaust air outlet passage, a rotation motor, a hydraulic impulse generator, and is connected to a stationary programmable control unit. The impulse wrench also includes a torque indicating mechanism connected to the control unit for feeding back electric signals responsive to the output torque of the wrench, an electromagnetically activated inlet valve arranged in the air inlet passage, and an electromagnetically activated exhaust valve which controls the exhaust air flow from the motor. The exhaust valve is a proportional valve activated by a linearly operated electromagnetic actuator and arranged to continuously adapt the exhaust air flow and, hence, the motor power to the characteristics of the actual screw joint being tightened in response to feed back signals from the torque indicating mechanism and in accordance with a programmed tightening strategy.

Abstract: An angle grinder including at least one boost mode unit configured to provide a boost mode, and a switching-over unit configured to switch over between a conventional mode and the boost mode.

Abstract: An electric power tool is powered by a plurality of battery packs connected in series. The electric power tool comprises a controller configured to receive signals outputted from the integrated circuits located in each of the battery packs. A first voltage level-shifter is disposed between the controller of the electric power tool and one of the integrated circuits of the battery packs. The first voltage level-shifter is configured to shift the voltage level of the signal outputted from the respective integrated circuit to the tool controller to an acceptable level for the controller.

Abstract: A method is provided for controlling an electric hand-held power tool having a device housing and a coupling device on the device housing side for securing an auxiliary handle to the device housing. It is detected whether the auxiliary handle is secured to the device housing and/or whether the auxiliary handle is gripped by a user. In addition, the instantaneous operating state is ascertained and evaluated. A protective function is activated when the occurrence of a critical operating case is recognized during the evaluation of the instantaneous operating state. It is provided that the evaluation of the instantaneous operating state and/or the activation of the protective function is/are carried out as a function of whether the auxiliary handle is secured to the device housing and/or whether the auxiliary handle is gripped by the user.

Abstract: This fastener driving device is equipped with an impact force applying device that repeatedly applies impact forces to a fastener; and a load cell that detects a reaction force acting on the impact force applying device. The impact force applying device stops the applying of the impact force to the fastener on the basis of a detection result of the reactive force.

Abstract: An improved method is provided for operating a power tool. The method includes receiving an input control variable from an input unit; receiving at least one tool parameter relating to the power tool; determining a derivative of the input control variable; selecting one of a plurality of control profiles based on the control input variable, the derivative of the input control variable, and the tool parameter, each control profile correlating the control input variable of the input unit to a rotational speed at which to drive the output shaft; and driving the output shaft at a rotational speed in accordance with the selected control profile.

Abstract: An improved method is provided for operating a power tool. The method includes receiving an input control variable from an input unit; determining a second derivative of the input control variable; selecting one of a plurality of control profiles based on the control input variable and the second derivative, each control profile correlating the control input variable of the input unit to a rotational speed at which to drive the output shaft; and driving the output shaft at a rotational speed in accordance with the selected control profile.

Abstract: An air tool or air motor lubricant for adding to compressed air, and the method of operating air tools with the lubricant, in which the lubricant comprises a mixture of a polyalphaolefin or polyalphaolefin blend having a viscosity in the range of 2 to 3000 cSt and a high molecular weight complex ester in a ratio of 1.3:1 to 20:1 of the polyalphaolefin or polyalphaolefin blend to the high molecular weight complex ester. The lubricant comprises about 58 to 90 vol % polyalphaolefin or polyalphaolefin blend and about 10 to 42 vol % high molecular weight complex ester. The mixture of polyalphaolefin or polyalphaolefin blend and high molecular weight complex ester is added in an amount in the air of about 0.2 to 0.6 ppm effective to generate a lubricant airborne mist concentration in exhaust air of 0.2 ppm or less.

Abstract: A fastening device may include a fastening tool body having a fastener on one end; a drive unit installed on the fastening tool body and providing fastening power to the fastener; a gyroscopic sensor that is installed on the fastening tool body and detects the displacement of the fastening tool body and outputs a detection signal thereof; an angle sensor that detects the angle of the fastening tool body and outputs a detection signal thereof to a controller; and the controller that receives the signals output from the gyroscopic sensor and the angle sensor and output a set actuating signal to the drive unit.

Abstract: In a method for controlling an electric machine tool having an electric motor for driving a rotating insertion tool, the electric machine tool is operated in one of multiple operating modes, and at least one parameter of the machine tool is detected. The instantaneous operating state of the electric machine tool is ascertained and evaluated based on the detected parameter. A protective function is activated when the presence of a critical operating situation is recognized during the evaluation of the instantaneous operating state. The instantaneous operating mode of the electric machine tool is detected, and the evaluation of the instantaneous operating state is adapted in each case to the instantaneous operating mode.

Abstract: A power tool includes: a drive unit for a tool; an operating device for activating the power tool; a measuring device for measuring a motion of the power tool; and a filter for filtering at least one measured value of the measured motion. The operating device is configured to reduce a power output of the drive unit when the filtered, measured value corresponds to a state of reduced ease of operation.

Abstract: The invention relates to an electrical machine tool, particularly a hand machine tool, having a contrast detection device, an analysis unit, and at least one sensor provided for capturing a surface of a work piece. According to the invention, the analysis unit is provided for detecting a differentiation of the surface from an at least partially automatic guide using data captured by a sensor.

Abstract: An electric-motor kitchen appliance, in particular an electric-motor handheld device, preferably a hand mixer, includes a switch. The invention also relates to a finger-actuated electric control for the switch, and to a method for switching on/off a kitchen appliance. The switch is unlocked when the safety switch is actuated by the finger of a user. The safety switch is electronically switched. The possibility of unintentionally operating the electric-motor of the kitchen appliance is reduced due to the manual operation of the two separate switches. As a result, the safety of the electric-motor kitchen appliance in the household is significantly increased.

Abstract: An electric power tool includes a motor; a speed reducer for transferring a rotational power of the motor at a reduced speed; and a reduction ratio changing unit for changing a reduction ratio of the speed reducer. The speed reduction mechanism includes an axially slidable changeover member and a gear member, the changeover member being engaged with or disengaged from the gear member depending on an axial slide position thereof. The reduction ratio changing unit includes a shift actuator for axially sliding the changeover member, a driving state detector for detecting a driving state of the motor, a slide position detector for detecting a slide position of the changeover member and a controller for driving the shift actuator and for changing a drive control of the shift actuator depending on detection results of the slide position detector unit and the driving state detector unit, respectively.

Abstract: A method for sequencing drill holes for a mobile drill rig is disclosed. The method may include receiving a hole pattern having a plurality of planned holes and generating at least a first group of parallel pathways and a second group of parallel pathways between the plurality of holes of the hole pattern. The first group of pathways may be angled relative to the second group of pathways. The method may also include selecting between the first group of pathways and the second group of pathways based on which group of pathways includes fewer total pathways.

Abstract: This invention is an installation of a protective apparatus to prevent safety problems of machine tools caused in machining work-load process. The protective apparatus is comprised of a circuit used to slowly rotate the loaded machine tool by stepping it at a low speed and low power one full turn to insure clear workload path, and before full power is applied. This protective system will activate the full power only if a full rotation is achieved without any obstacles caused by chuck wrench or work-load interference with machine parts. The machine will subsequently arm itself to go into full power rotation if the operator activates the machine within a short period of time after the safety rotation is completed. The safety cycle is performed each time the operator activates the machine tool. This protective apparatus keeps the machine tool in low-speed and low-power unless the safety cycle has been performed each time the machine tool is turned on.

Abstract: An orthopedic impacting tool comprises a motor, a linear motion converter, an air chamber, a compression piston, an impacting element, an anvil element, and a broach adapter. The compression piston may cause the impacting element to apply controlled force on a broach adapter to create a precise opening for subsequently disposing a prosthesis in a patient. The tool may further comprise a detent for holding the impacting element in a position until a sufficient pressure is applied to release the impacting element. The tool allows forward or backward impacting for expanding the size or volume of the opening or for facilitating removal of the broach and tool from the opening. A force adjustment control of the tool allows a user to increase or decrease the impact force. A light source and hand grips improve ease of operation of the tool.

Abstract: A chain saw as a power tool includes a combustion engine and an electric motor. The chain saw has a driving shaft which drives a saw chain, a battery pack which provides electric current to the electric motor, a controller which is connected to the battery pack, and a sensor which detects a driving state of a driving mechanism including the combustion engine and the electric motor. In the chain saw, the saw chain is driven in a hybrid driving mode in which both the combustion engine and the electric motor drive the driving shaft. Further, the controller controls a driving of the combustion engine based on a detection result of the sensor.

Abstract: A chain saw as a power tool includes a combustion engine and an electric motor. The chain saw has a driving shaft which drives a saw chain, a battery pack which provides electric current to the electric motor, and a controller which is connected to the battery pack. In the chain saw, both the combustion engine and the electric motor drive the driving shaft so that the driving shaft drives the saw chain. Further, the controller controls a driving of the electric motor based on a remaining capacity of the battery pack.

Abstract: A rotary tool includes an externally operable operation switch; a motor serving as a power source; a power transfer block for transferring the rotation of the motor; a load detection unit for detecting an amount of load of the motor; and a control unit for controlling the motor. The control unit is configured to perform an operation control by which the motor is controlled so that a rotation speed of the motor is increased in proportion to the operation amount of the operation switch and a feedback control by which the rotation speed of the motor is controlled depending on the detection result of the load detection unit. The control unit inhibits the feedback control during the time when the operation amount of the operation switch is equal to or less than a threshold and performing the feedback control only when the operation amount of the operation switch is greater than the threshold.

Abstract: A method for detection of false positive condition that an object is in contact with an implement in a power tool includes sampling an electrical signal received from the implement, identifying in-phase and a quadrature components of the sampled electrical signal, identifying a magnitude of each of the samples with reference to the in-phase component and the quadrature component for the samples, detecting an object approaching the implement with reference to the plurality of samples, identifying a signal-to-noise ratio for the samples, and identifying a false positive condition for the detected object with reference to the identified signal-to-noise ratio for the identified samples.

Abstract: A rotary impact tool includes: a hammer rotating by receiving a rotational force of a motor; an anvil rotating by receiving a rotational force of the hammer; and an end tool attached to the anvil, the rotary impact tool being constructed such that when a torque of a value not less than a predetermined value is applied to the anvil from the outside, the hammer is disengaged from the anvil to rotate idle and applies an impact to the anvil in a rotational direction after rotating idle by a predetermined angle, the rotary impact tool including an impact detector configured to detect impacts and a speed switching device configured to switch the rotational speed of the motor, and when the impact detector detects an impact during rotation of the anvil in a tightening direction, the speed switching device switches the rotational speed of the motor from a normal speed to a low speed.

Abstract: A hand-guided work apparatus includes a combustion engine to drive a work tool. The combustion engine includes a crankcase (14) in which a crankshaft (16) is rotatably mounted about a rotational axis (44). A pressure sensor (27) and a temperature sensor (26) are arranged on the crankcase (14). The pressure sensor (27) and the temperature sensor (26) are arranged in a common sensor housing (31). In the typical put-down position (8) of the work apparatus, the pressure sensor (27) and the temperature sensor (26) are arranged below a plane (45) which is parallel to the horizontal storage surface (7) and contains the rotational axis (44) of the crankshaft (16). A connecting channel (25) is formed in the sensor housing (31). The connecting channel (25) connects the pressure sensor (27) to the crankcase interior (20) and the base (35) of the connecting channel (25) slopes down toward the crankcase interior (20) in the typical put-down position (8) of the work apparatus.

Abstract: Embodiments provide methods, apparatuses, and systems for battery operated tools, such as chainsaws, are provided. In accordance with embodiments herein, a chainsaw may include various components, such as a control board having a controller, a battery terminal block, a motor, a brake switch, a trigger switch, and/or other components. In various embodiments, components of the battery operated tool are provided that improve the capabilities and/or operation of the tool.

Abstract: A Single Piezo-Actuator Rotary-Hammering (SPaRH) Drill includes a horn actuator having high power piezoelectric materials and a flexure pre-stress to increase the actuators effectiveness. The drill is a low mass, low power, compact coring drill measuring 20-cm high by 7-cm diameter and having a total weight of 2 kg including drive electronics. Using an average power of 50-Watts, the drill basalt is expected to cut basalt at a rate of 0.2 cm/min down to depth of 10-cm and create cuttings and an intact core. The drill is expected to operate under different environments including Martian ambient (6 Torr and down to ?50° C.), and liquid nitrogen temperatures (77 K) and low pressure (<<1 Torr) to simulate lunar polar and Europa conditions. Materials expected to be sampled include Kaolinite, Saddleback Basalt, Limestone, Volcanic Breccia, Siltstone, ice, permafrost and layered rocks with different hardness.

Abstract: A hand-held power tool includes a drive device in a housing. The drive device is intended to drive a tool accommodated in a tool-accommodating region. An adjusting motion of the hand-held power tool by the user is detected via a sensor device. A controlled variable for setting the drive device is generated in an open-loop or closed-loop control device in the hand-held power tool according to the detected adjusting motion.

Abstract: A power saw having a reciprocating blade, including a housing having a handle portion for holding the saw; a variable speed motor in the housing for driving the reciprocating blade; a mechanism configured to move the reciprocating blade in a non-linear path; an electronic controller for controlling the operation of the motor; a trigger switch configured to provide an electrical signal to the controller that is proportional to the amount of travel that the switch is moved, wherein the signal causes the controller to operate the motor through a range of operating speeds; and a mode switch operatively connected to the controller and including a first mode providing normal operating speeds responsive to the trigger switch being selectively moved through its range of travel, and a second mode wherein the operating speeds are within the range of about 50% to about 80% of the normal operating speeds.

Abstract: An electrical combination including a power tool and a battery pack. The power tool includes power tool terminals. The battery pack is configured to be interfaced with the power tool. The battery pack includes a battery pack housing, at least three terminals, and a plurality of battery cells. The battery pack terminals include a positive terminal, a negative terminal, and a sense terminal. The at least three terminals are configured to be interfaced with the power tool terminals. The plurality of battery cells are arranged within and supported by the battery pack housing. Each of the battery cells has a lithium-based chemistry and a respective state of charge, and power is transferable between the battery cells and the power tool. A circuit is configured to monitor the battery cells, detect a charge imbalance among the battery cells, and prevent the battery pack from operating when the charge imbalance is detected.

Abstract: A combination of electric tools includes a first electric tool and a second electric tool respectively having an independent power supply. The second electric tool starts working automatically responding to the startup of the first electric tool. Thereby the second electric tool starts automatically after the first electric tool is started to operate by a user without an extra operation of the user, which is convenient to the user.

Abstract: A motor control device includes a target value setting unit, a measuring unit, a deviation calculating unit, a proportional control unit, an integral control unit, and a disabling unit. The deviation calculating unit calculates a deviation between a target value, set by the target value setting unit, and a measured value for rotational speed, measured by the measuring unit. The disabling unit disables proportional control, performed by the proportional control unit, when the deviation, calculated by the deviation calculating unit, is a value within a predetermined range.