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公开(公告)号:EP0642970B1
公开(公告)日:1997-11-12
申请号:EP94114287.9
申请日:1994-09-12
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公开(公告)号:EP0642970A1
公开(公告)日:1995-03-15
申请号:EP94114287.9
申请日:1994-09-12
发明人: Haga, Kyosuke , Suzuki, Mikio , Fukumura. Kenichi , Kato, Hideya , Kawakami, Seiho[ , Saito, Kaname
摘要: A hydraulic power steering system includes a pump (1), a flow control valve (4), and a bypass control valve (20). The flow control valve (4) responds to a pressure drop across a metering orifice (3) disposed in a fluid supply passage (2) so as to control the flow rate of operational fluid by bypassing part of the operational fluid to a reservoir (11). A spring chamber (6a) of the flow control valve (4) is connected to the supply passage (2) through a control orifice (7). The bypass control valve (20) is disposed between the spring chamber (6a) and the reservoir (11) so as to increase the amount of bypassed fluid by controlling the pressure in the spring chamber (6a). The bypass control valve (20) has a control spool (21), a load pressure introduction port (23A) connected to the upstream side of the control orifice (7) for leading the load pressure to a first end of the control spool (21) and a pilot port (23B) connected to the downstream side of the control orifice (7) for leading the pressure in the spring chamber (6a) of the flow control valve (4) to a second end of the control spool (21). Moreover, a pressure receiving area of the second end of the control spool (21) is smaller than that of the first end of the control spool (21). Accordingly, a spring (22) having a small spring constant can be used in the bypass control valve (20), even when the control spool (21) is controlled within a short stroke.
摘要翻译: 液压动力转向系统包括泵(1),流量控制阀(4)和旁路控制阀(20)。 流量控制阀(4)响应布置在流体供应通道(2)中的计量孔(3)上的压降,以通过将部分工作流体绕过储存器(11)来控制工作流体的流量 )。 流量控制阀(4)的弹簧室(6a)通过控制孔(7)连接到供应通道(2)。 旁路控制阀(20)设置在弹簧室(6a)和贮存器(11)之间,以通过控制弹簧室(6a)中的压力来增加旁路流体的量。 旁通控制阀20具有控制滑阀21,与控制节流孔7的上游侧连接的负荷压力导入口23A,用于将负荷压力导向控制滑阀21的一端 )以及连接到控制节流孔(7)的下游侧用于将流量控制阀(4)的弹簧室(6a)中的压力导向控制阀芯(21)的第二端的先导端口(23B) 。 此外,控制阀芯(21)的第二端的受压面积小于控制阀芯(21)的第一端的受压面积。 因此,即使当控制阀芯(21)在短行程内被控制时,旁路控制阀(20)中也可以使用弹簧常数小的弹簧(22)。
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