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In a small electric motor vehicle equipped with an electric motor for driving wheels through a reduction gear mechanism, a first predetermined voltage is immediately applied to the electric motor when a drive-off instruction is generated from vehicle standstill and then the voltage is increased at a

In a small electric motor vehicle equipped with an electric motor for driving wheels through a reduction gear mechanism, a first predetermined voltage is immediately applied to the electric motor when a drive-off instruction is generated from vehicle standstill and then the voltage is increased at a predetermined rate until the voltage exceeds a second predetermined voltage, and is then controlled such that the driving speed converges to a desired speed. With this, since the application of the first predetermined voltage slightly rotates the electric motor to take up reduction gear mechanism backlash, shock at drive-off caused by reduction gear mechanism backlash can be reduced or eliminated even when a high-capacity electric motor is used to enhance hill-climbing performance, and smooth drive-off is possible. Furthermore, since the rate of increase/decrease of the driving speed is varied in proportion to the difference between a set speed and a calculated command speed, the driving feel is therefore improved.

대표청구항 ▼

In a small electric motor vehicle equipped with an electric motor for driving wheels through a reduction gear mechanism, a first predetermined voltage is immediately applied to the electric motor when a drive-off instruction is generated from vehicle standstill and then the voltage is increased at a

In a small electric motor vehicle equipped with an electric motor for driving wheels through a reduction gear mechanism, a first predetermined voltage is immediately applied to the electric motor when a drive-off instruction is generated from vehicle standstill and then the voltage is increased at a predetermined rate until the voltage exceeds a second predetermined voltage, and is then controlled such that the driving speed converges to a desired speed. With this, since the application of the first predetermined voltage slightly rotates the electric motor to take up reduction gear mechanism backlash, shock at drive-off caused by reduction gear mechanism backlash can be reduced or eliminated even when a high-capacity electric motor is used to enhance hill-climbing performance, and smooth drive-off is possible. Furthermore, since the rate of increase/decrease of the driving speed is varied in proportion to the difference between a set speed and a calculated command speed, the driving feel is therefore improved. ng sealed in the package, the tuning fork type piezoelectric resonator element having excitation electrodes including first electrodes formed on main surfaces of the surfaces of the resonating arms, and second electrodes formed on side surfaces of the surfaces of the resonating arms, the first electrodes including an electrode film that is coated on the side surfaces of a groove formed lengthwise on at least one of the main surfaces of the resonating arms. 9. A piezoelectric device, comprising: a package for a piezoelectric device, comprising: a base defining a top surface and an outer periphery and having a rectangular box shape; low-melting point glass; a lid defining a periphery and made of a thin rectangular glass sheet and bonded onto the top surface of the base via the low-melting point glass, corners of the rectangular lid being removed so as to define a margin with a specified width between the outer periphery of the base and the periphery of the lid; and a piezoelectric resonator element hermetically sealed in a space defined by the base and the lid; and a tuning fork type piezoelectric resonator element having a base portion that is fixed on the base of the package and a pair of resonating arms, the tuning fork type piezoelectric resonator element being sealed in the package, the base portion of the tuning fork type piezoelectric resonator element having a constriction formed between a part fixed to the base and the resonating arms. 10. The piezoelectric device according to claim 8, further including an IC device mounted in the package. 11. The piezoelectric device according to claim 9, further including an IC device mounted in the package. 12. The piezoelectric device of claim 9, wherein the base has a through hole by which an inside of the package communicates with an exterior, the through hole being hermetically closed with a sealing medium. 13. A package for a piezoelectric device, comprising: a base defining a top surface and an outer periphery and having a rectangular box shape; low-melting point glass; a lid defining a periphery and made of a thin rectangular glass sheet and bonded onto the top surface of the base via the low-melting point glass, corners of the rectangular lid being removed so as to define a margin with a specified width between the outer periphery of the base and the periphery of the lid; and a piezoelectric resonator element hermetically sealed in a space defined by the base and the lid, wherein the base has a through hole by which an inside of the package communicates with an exterior, the through hole being hermetically closed with a sealing medium.