| US 7,523,610 B2 | ||
| Neutral valve structure | ||
| Shigenori Sakikawa, Hyogo (Japan) | ||
| Assigned to Kanzaki Kokyukoki Mfg. Co., Ltd., Hyogo (Japan) | ||
| Filed on May 18, 2006, as Appl. No. 11/435,821. | ||
| Claims priority of application No. 2005-149091 (JP), filed on May 23, 2005. | ||
| Prior Publication US 2006/0260302 A1, Nov. 23, 2006 | ||
| Int. Cl. F16D 31/02 (2006.01) | ||
| U.S. Cl. 60—468 [60/489] | 12 Claims |
| 6. A neutral valve structure applied to a port block in which a pair of first and second operation passages configuring at
least parts of a pair of operation fluid lines in an HST are formed substantially in parallel with each other,
(a) the port block including:
(i) a linear installation passage intersecting with the first operation passage and having a tip end extending beyond the
first operation passage and a base end opened to an outer surface;
(ii) a releasing passage having a first end fluidly connected to a portion, of the installation passage, extending to the
tip-end side beyond the first operation passage and a second end fluidly connected to a low-pressure area; and
(iii) a neutral valve inserted into the installation passage from the base end and switching fluid-connection or fluid-disconnection
between the first operation passage and releasing passage according to the hydraulic pressure of the first operation passage;
(b) the neutral valve including:
(i) a valve body inserted into the installation passage in a slidable manner along the axis line direction so as to straddle
the first operation passage, the valve body capable of taking a releasing position on one side of the axis line direction
where the first operation passage and the releasing passage are fluidly connected to each other, and a closing position on
the other side of the axis line direction where the first operation passage and the releasing passage are fluidly disconnected
to each other;
(ii) a biasing member having a tip end engaged to the valve body so as to urge the valve body toward the releasing position
on one side of the axis line direction; and
(iii) a lid member engaging a base end of the biasing member and defining a spring chamber for accommodating the biasing member
between the valve body and the lid member; and
(c) the valve body including:
(i) a closing-side pressure-receiving portion for receiving the hydraulic pressure of the first operation passage so as to
press the valve body toward the closing position on the other side of the axis line direction against the urging force of
the biasing member; and
(ii) a releasing-side pressure-receiving portion for receiving the hydraulic pressure of the first operation passage so as
to press the valve body toward the releasing position on one side of the axis line direction along with the biasing member,
the releasing-side pressure-receiving portion having a receiving pressure area smaller than that of the closing-side pressure-receiving
portion.
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