Engine braking device with returning and limiting functions and engine

An engine braking device with returning and limiting functions, comprising:

• a camshaft comprising an auxiliary cam, an outer contour of the auxiliary cam being provided with a non-working surface and a working surface, wherein a distance between the working surface and a base circle center of the auxiliary cam is greater than a distance between the non-working surface and the base circle center of the auxiliary cam;
• a brake rocker arm and a rocker arm shaft that mate via a shaft hole, the brake rocker arm being swingable back and forth around the rocker arm shaft, and an axis direction of the rocker arm shaft and an axis direction of the camshaft being parallel to each other, wherein a lateral portion of the brake rocker arm extends in a horizontal direction to form a butting platform, an outer surface of the rocker arm shaft is provided with a limiting recess, both sides of the limiting recess are provided with a first butting surface A and a first butting surface B, respectively, the brake rocker arm is provided with a limiting protrusion in concave-convex mating with the limiting recess, both sides of the limiting protrusion are provided with a second butting surface A and a second butting surface B, respectively, and a relative distance between the second butting surface A and the second butting surface B is less than a relative distance between the first butting surface A and the first butting surface B;
• a rocker arm support base, wherein both ends of the rocker arm support base are mated with a shaft hole of the camshaft and the shaft hole of the rocker arm shaft, respectively, and an end of the rocker arm support base mated with the shaft hole of the camshaft is provided with a first connecting portion;
• a return spring bracket with an end connected to the first connecting portion via a fastener or connected to a second connecting portion on the rocker arm shaft, wherein a horizontal height of the first connecting portion and a horizontal height of the second connecting portion are both higher than a horizontal height of the butting platform, and a horizontal height of the return spring bracket is lower than a horizontal height of an upper surface of the brake rocker arm;
• a slidable unit slidably connected to an end of the brake rocker arm corresponding to the auxiliary cam, the slidable unit being provided with a wheel, wherein an axis direction of the wheel and the axis direction of the camshaft are parallel to each other;
• and
• a first elastic member with both ends sandwiched between the other end of the return spring bracket and the butting platform, wherein an axis of the first elastic member is biased to a side of a connecting line between a circle center of the auxiliary cam and a circle center of the wheel, and the first elastic member is located between the wheel and the rocker arm shaft;
• wherein when an engine works normally, a gap exists between the wheel and the working surface of the auxiliary cam, the first butting surface A and the second butting surface A butt against each other, and the first elastic member is in an energy storage state;
• and
• when the engine is in a braked state, the wheel contacts the outer contour of the auxiliary cam, and as the working surface and the non-working surface on the auxiliary cam alternately contact the wheel, the brake rocker arm is caused to swing back and forth around the rocker arm shaft, and the limiting protrusion is caused to swing back and forth inside the limiting recess.