Speed switching circuit

Abstract

The invention discloses a speed switching circuit. The speed switching circuit comprises a microprogrammed control unit U2 and a power transistor Q2, wherein a capacitor C5 is connected between VDD and VSS of the microprogrammed control unit U2; a third pin, a sixth pin and a seventh pin of the microprogrammed control unit U2 are grounded respectively after passing through a resistor R11, a resistor R5 and a resistor R6; a fifth pin of the microprogrammed control unit U2 is connected with a 5V signal through a resistor R7; after a resistor R15, a capacitor C8 and a voltage-regulator tube Z2 are connected in parallel, one end of the resistor R15, one end of the capacitor C8 and one end of the voltage-regulator tube Z2 are connected with the power transistor Q2, and the other ends of the resistor R15, the capacitor C8 and the voltage-regulator tube Z2 are connected with a combination diode D2 through a series resistor R13; one end of the power transistor Q2 is grounded, and the other end of the power transistor Q2 is connected with a P5 end; a power transistor Q4 is connected with the combination diode D2 through a series resistor R18; the power transistor Q4 is also connected with a resistor R20; the resistor R20 is connected with a capacitor C11 and P6; and a resistor R9 and a capacitor C10 are connected with a resistor R12 and the power transistor Q4 after being connected in parallel. Through adoption of the electronic speed switch, the problem involved with service life can be solved well. The electronic speed switch is free from contacts, so that the service life can be fully up to 5,000,000 times or more once the design is reasonable.

Description

technical field [0001] The invention relates to the technical field, in particular to a speed switch circuit. Background technique [0002] For cars that often travel in mountainous or hilly areas, in order to continuously reduce or maintain a stable vehicle speed for a long time when going down a long slope and reduce or release the load on the service brake, it is usually necessary to install an auxiliary braking device such as a retarder. [0003] The eddy current retarder is generally controlled by a mechanical handle switch. If the mechanical handle does not return after the driver stops, the eddy current retarder will always be in working condition and consume a large amount of current, causing the vehicle to Power loss; In order to avoid this situation, a device such as a speed switch is introduced. [0004] The speed switch is used to control the eddy current retarder to avoid the eddy current retarder working when the vehicle speed is low or when the vehicle is sto...

AI Technical Summary

Problems solved by technology

[0003] The eddy current retarder is generally controlled by a mechanical handle switch. If the mechanical handle does not return after the driver stops, the eddy current retarder will always be in working condition and consume a large amount of current, causing the vehicle to Power loss; in order to avoid this situation, a device such as a speed switch is introduced

[0004] The speed switch is used to control the eddy current retarder to avoid the eddy current retarder working when the vehicle speed is low or when the vehicle is stopped. The speed switch currently being used in the market uses a relay to control the eddy current retarder. The relay is generally only 100,000 The service life of the speed switch is 3 million times, even if a special customized relay is used, the service life is difficult to reach 1 million times

Images