Brake oil level safety device for motor vehicles

A motor vehicle safety device including a microswitch connected in series between the ignition system and battery power supply of a motor vehicle, and a float device disposed in the brake oil cup of the oil brake system of the motor vehicle and actuated to switch off the microswitch when the level of the brake fluid in the brake oil cup of the oil brake system of the motor vehicle drops below a predetermined level.

BACKGROUND OF THE INVENTION 
The present invention relates to a motor vehicle safety device for the oil 
brake system of a motor vehicle which automatically cuts off power supply 
from the ignition system when the fluid level of the brake fluid in the 
brake oil cup of the oil brake system of the motor vehicle drops below a 
critical level. 
It is reported that many traffic accidents which were caused by brake 
failures happened because the drivers didn't know that the brake fluid had 
dropped below the safety critical level. According to tests, when the 
brake fluid in the brake oil cup of the oil brake system of a motor 
vehicle drops below 1/5 of the full fluid level, a brake failure will 
occur. Therefore, a possible traffic accident can be prevented if power 
supply is cut off from the ignition system when the brake oil drops below 
the safety critical level. 
SUMMARY OF THE INVENTION, 
It is one object of the present invention to provide a motor vehicle safety 
device which automatically cuts off power supply from the ignition system 
when the fluid level of the brake fluid in the brake oil cup of the oil 
brake system of the motor vehicle drops below a critical level. It is 
another object of the present invention to provide a motor vehicle safety 
device which is simple in structure and practical in use.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 and 2, a microswitch 4 is mounted on the outside wall 
of the brake oil cup 1 of a motor vehicle brake system. A cover 2 is 
pivotably connected to the brake oil cup 1 by a pivot 23, having a 
downward guide rod 21 suspended in the brake oil cup 1 and terminating in 
a disk 22. A float 3 is mounted around the guide rod 21 and moved in the 
brake oil cup 1 between the disk 22 and the cover 2. When the brake oil 
cup 1 is filled up with the brake oil, the float 3 is moved upwards to 
lift the cover 2 from the microswitch 4, causing the microswitch 4 to be 
switched on (See FIG. 1A). On the contrary, when the float 3 is moved 
downwards from the cover 2 and the cover is covered on the brake oil cup 
1, the microswitch 4 is switched off (see FIG. 2A). 
Referring to FIGS. 3A, 3B and 1A again, the two opposite ends of the 
microswitch 4 are respectively connected to the ignition system 5 and the 
battery power supply 6 of the motor vehicle by electric wires. When the 
microswitch 4 is switched on, the ignition system 5 and the battery power 
supply 6 are electrically connected (see FIGS. 1A and 3A); when the 
microswitch 4 is switched off, the ignition system 5 and the battery power 
supply 6 are electrically disconnected (see FIGS. 2A and 3B). The lower 
limit of the float 3 is set at one fifth of the full brake oil level of 
the brake oil cup 1. Therefore, when the brake oil level drops below one 
fifth of the full brake oil level, the microswitch 4 is switched off, and 
the ignition system 5 is electrically disconnected from the battery power 
supply 6 to stop the engine. 
FIGS. 4A, 4B, 5A, and 5B show another application example of the present 
invention installed in the oil damping device 7 of a diesel engine. The 
oil damping device 7 comprises an oil inlet 75 connected to the oil tank 
(not shown), an oil outlet 76 connected to an oil pump (not shown), an 
inner tube 74 moved on the inside, an electromagnet 73 connected to the 
inner tube 74 and controlled by a spring 72 and a winding 71 to move the 
inner tube 74 between the oil inlet 75 and the oil outlet 76. When the 
winding 71 does no work, the inner tube 74 is forced forward by the spring 
72 to impart an oil passage between the oil inlet 75 and the oil outlet 76 
(see FIG. 4A); when the winding 71 is energized to attract the 
electromagnet 73, the inner tube 74 is moved backward to block up the oil 
passage between the oil inlet 75 and the oil outlet 76 (see FIG. 4B). 
Therefore, when the microswitch 4 is electrically connected between the 
battery power supply 6 and the winding 71, the oil damping device can then 
be automatically controlled by the safety device of the present invention. 
When the microswitch 4 is switched off, the brake oil is allowed to pass 
through the oil damping device 7 (see FIG. 5A); on the contrary, when the 
microswitch 4 is switched on, the brake oil is not allowed to pass through 
the oil damping device 7 (see FIG. 5B) and the diesel engine is stopped. 
While it is apparent that the invention herein disclosed is well calculated 
to fulfill the objects above stated, it will be appreciated that numerous 
modifications and embodiments may be devised by those skilled in the art, 
and it is intended that the appended claims cover all such modifications 
and embodiments as fall within the spirit and scope of the invention.