NOVELTY - A thermostat comprises throttle valve on shaft in throttle tube, controlling box is outside the throttle tube and bimetal sheets and adjusting sliding block are inside the controlling box, where throttle valve (3) is clamped in the axis in the throttle tube (1), central end of the bimetal sheets (7) is fastened by fixing limit screw (6) and its terminal is encircled anti-quitting pin (10), adjusting sliding block (8) is clamped on the wall of controlling box (5), there is closing state limit bulge (11), maximum opening degree limit bulge (13), and middle screw of reset spring (12).    USE - The thermostat is used for automatically adjusting temperature of controlled thermal reaction device. It is especially used for controlling temperature of controlled thermal reaction cavity in vehicle device to prepare hydrogen (mobile reformer for preparing hydrogen), and is also used for automatic controlling element applied to vehicle fuel system.    ADVANTAGE - The thermostat takes bimetal sheets (7) as pushing mechanism of thermo-sensitive element and throttle valve (3), and makes it connect on throttle pipe of the heat source gas of the controlled thermal reaction device, and the controlled thermal reaction device can control the temperature in the controlled thermal reaction cavity without by-pass pipeline of the heat source gas and external means. It simplifies system of the controlled thermal reaction device and the controlling method.    DETAILED DESCRIPTION - A thermostat comprises throttle valve on shaft in throttle tube, controlling box is outside the throttle tube, and bimetal sheets and adjusting sliding block are inside the controlling box, the throttle tube is connected on the throttle pipe of the heat source gas of the controlled thermal reaction device, where two opposite axial holes are in middle part of tubular wall containing the throttle tube (1), screw thread end of shaft (4) is passed through lower wall hole from the upper wall hole of the throttle tube (1), nut is meshed on the screw thread end of shaft (4), throttle valve (3) is clamped in the middle of the axis in the throttle tube (1), upper end groove of the shaft (4) is clamped with central end of the helical bimetal sheets (7), central end of the bimetal sheets (7) clamped in the upper end groove of the shaft (4) is fastened by fixing limit screw (6), controlling box (5) is on the external wall of the throttle tube (1), and adjusting groove is in the middle of right semi-circle of the wall of the controlling box (5), the adjusting sliding block (8) of inner wall of the controlling box (5) is clamped on the wall of the controlling box (5) through adjusting screw perforated the adjusting groove, terminal of the helical bimetal sheets (7) is encircled anti-quitting pin (10) after passing through rectangular hole of the adjusting sliding block (8), and there is closing state limit bulge (11) of throttle valve (3) and maximum opening degree limit bulge (13) on inner wall of the controlling box (5), middle screw of reset spring (12) is sleeved on highest end of the shaft (4), two arms and one end of the reset spring (12) are hung in the hole for clamping the limit screw (6), and another arm is hung in the hole on the maximum opening degree limit bulge (13).    DESCRIPTION OF DRAWING(S) - The drawing shows the front view of the thermostat.    Throttle tube (1)    Throttle valve (3)    Controlling box (5)    Fixing limit screw (6)    Bimetal sheets (7)    Adjusting sliding block (8)