| 摘要 |
<p>The invention relates to a device for engine breaking in motor vehicles comprising an internal combustion engine with at least one cylinder, at least one exhaust valve at said cylinder and a rocker arm (4) for activation of said exhaust valve, which rocker arm (4) is arranged on a hollow rocker arm shaft (5) and arranged to be effected by ridges (2a, 2b, 2c) on a camshaft (2), said device additionally comprising a control valve (15, 16) for controlling the oil pressure in said rocker arm shaft (5), and means (6; 14) receptive to an increase of the oil pressure in said rocker arm shaft (5) being integrated in said rocker arm (4) for absorbing a play between said rocker arm (4) and said exhaust valve in the case of increase oil pressure, with at least one of said ridges (2b, 2c) then causing opening of the exhaust valve with an engine breaking effect. The invention is characterized in that said control valve (15) comprises an adjustable valve body (18, 19) and a canal (23) between the valve body (18, 19) and the rocker arm shaft (5) which comprises a controlable exhaust (36), the valve body (18, 19) being arranged to be positioned in a first position with pressure reducing effect and a second position without pressure reducing effect. The invention also relates to a method for such engine breaking. By means of the invention an engine breaking is obtained which is particularly suitable for use for a rapid decrease of the engine speed when shiftings in a gearbox associated with the engine.</p> |
