of an elastic diaphragm 22 is fastened by a circumference of the wall between the two housing parts 20 21 the diaphragm 22 rests with the circumference on a radially inward extending clamping collar 59 of the lower housing part 20 and the circumference of the diaphragm is elastically pressed by the edge 55 of the upper housing part 21 into its locked state and retained there the diaphragm 22 divides a valve chamber 24 from an opposite control chamber 25 the control chamber 25 communicates with the negative pressure connection 16 of the valve 15 on the side of the diaphragm 22 toward the negative pressure connection 16 a diaphragm plate 26 is joined to the diaphragm 22 the diaphragm plate serves to lend a certain rigidity to the diaphragm 22 and to support a spring 27 the spring 27 contacts the diaphragm plate 26 and rests on a bottom of the 28 upper housing part 21 if needed the diaphragm plate 26 can be made heavier with weights therefore the operating noise of the valve 15 is modified to enable optimal noise tuning in the vehicle by an adapted vibration tuning the diaphragm 22 on the side remote from the negative pressure connection 16 and toward.