| 摘要 |
<p>1469484 Change-speed control ROBERT BOSCH GmbH 18 April 1974 [19 April 1973] 16925/74 Heading F2D A valve spool 22 governing a control pressure in an outlet 7 which leads to a main regulating valve (not shown) controlling ratio selection in a vehicle gear-box is displaced by pressure variations in a chamber 46 controlled by a pilot valve plunger 39 actuated by a solenoid 11 subject to electrical signals 10 dependent upon engine speed and/or throttle valve position, and a spool 16 limits the maximum value of the control pressure. When the pilot valve is controlled by throttle valve position an increase in throttle opening causes approach of the plunger 39 towards a seat 43 to increase the pressure in the chamber 46 and cause leftward movement of the spool 22 to connect an hydraulic pressure supply line 15 with the outlet 7 and thereby increase the pressure in the latter. The increased outlet pressure acts through a bore 21 on the left-hand end of the spool to oppose the pressure in 46. When the throttle valve is fully opened the plunger 39 engages the seat 43 and causes maximum leftward displacement of the spool 22 so that a spring abutment 41 is displaced and this, together with the pressure in the outlet 7 acting on the right-hand end of the spool 16 causes the latter to limit the outlet pressure by opening an exhaust 17b. The maximum leftward displacement of the spool 22 also connects a passage 27 in the spool with an outlet 8 leading to a kick-down valve (not shown).</p> |
