Incompressible fluid injection apparatus

A grease injection valve 10 is provided having a valve body 16 including a flow path 15 the valve body. A foreign matter intrusion prevention valve 18 is provided at the upstream side of a check valve 17 in the flow path 15 of valve body 16. Grooves 47 are positioned around the periphery of a foreign matter intrusion prevention valve body 44 in the flow path 15 to provide communication between the downstream side and the upstream side of the foreign matter intrusion prevention valve body 44. When the check valve 17 has a functional failure, high-pressure grease escapes through the grooves 47 to bypass the foreign matter intrusion prevention valve body 44 and is discharged to an exterior of the grease injection valve 10. This can avoid excessive pressure caused by the grease backflow from being applied to the foreign matter intrusion prevention valve 18.

TECHNICAL FIELD

The present disclosure relates to an incompressible fluid injection apparatus including a check valve provided in the middle of a flow path of a valve body and a foreign matter intrusion prevention valve provided at the upstream side of the check valve of the flow path of the valve body.

BACKGROUND

Conventionally, an injection valve is used for a crawler tension adjustment mechanism for adjusting the tension of a crawler running apparatus of a crawler-type vehicle, for example a hydraulic shovel. The injection valve includes a valve body having a flow path through which an incompressible fluid such as grease flows to a sealed chamber in a cylinder body. During injection of this incompressible fluid, a spherical check valve that is provided in the middle of the flow path of the valve body prevents the backflow of the incompressible fluid, and a foreign matter intrusion prevention valve is provided at the upstream side of this check valve. See Japanese Unexamined Patent Application Publication No. 2010-215207 and Publication No. 2012-233538 for examples. In this configuration however, there is a concern that a failure of the check valve allows the incompressible fluid to backflow in the flow path at high pressure and damage the foreign matter intrusion prevention valve.

A configuration is illustrated is in Japanese Unexamined Patent Application Publication No. 2012-148592 in which a groove is provided at an attachment screw on the outer side of an injection valve to thereby allow fluid to escape from the downstream side. In the case of this configuration however, the pressure cannot escape unless the injection valve is first loosened.

SUMMARY

The present disclosure is directed to providing an incompressible fluid injection apparatus that can suppress, when the check valve fails to function, an excessive pressure caused by the backflow of incompressible fluid from being applied to the foreign matter intrusion prevention valve.

In one aspect, the present disclosure provides an incompressible fluid injection apparatus that includes a valve body including a flow path through which incompressible fluid flows to the discharge side during injection of the incompressible fluid. A check valve is provided in the middle of the flow path of this valve body that prevents the backflow of the incompressible fluid. The apparatus further includes a foreign matter intrusion prevention valve provided at the upstream side of the check valve in the flow path of the valve body, the intrusion prevention valve having a spring for biasing a spherical valve body to close an upstream part of the flow path, and grooves provided around the periphery of spherical valve body to provide fluid communication between the downstream side and the upstream side of this foreign matter intrusion prevention valve body.

When the check valve fails, although high-pressure incompressible fluid may backflow to the foreign matter intrusion prevention valve, the existence of the grooves providing communication between the downstream side and the upstream side of the foreign matter intrusion prevention valve body allows the high-pressure incompressible fluid to bypass the foreign matter intrusion prevention valve body and be discharged to the exterior of the apparatus. This can suppress an excessive pressure caused by the backflow of the incompressible fluid from being applied to the foreign matter intrusion prevention valve.

The grooves may be provided at substantially-equal intervals in the valve seat surrounding the spherical valve body so that the fluid can be discharged to the exterior through these grooves in a secure and substantially-uniform manner.

DETAILED DESCRIPTION

InFIG. 1A, the reference numeral10denotes a grease injection valve functioning as an incompressible fluid injection apparatus (hereinafter simply referred to as an injection valve). This injection valve10is used, for example, for a crawler tension adjustment apparatus that adjusts the crawler tension of a pair of left and right crawler running apparatuses of a base carrier of a hydraulic shovel.

The crawler tension adjustment apparatus includes an adjuster cylinder. The crawler tension adjustment apparatus is a known one in which the grease inclusion amount is changed via an injection valve10into a sealed chamber of this adjuster cylinder to thereby change the protrusion amount of the piston rod of the adjuster cylinder so that an idle wheel is moved to increase or decrease the crawler tension.

The injection valve10includes a valve body16having a flow path15through which grease flows to the sealed chamber side of the adjuster cylinder during the injection of the grease, a check valve17provided in the middle of the flow path15, and a foreign matter intrusion prevention valve18that is provided in the flow path15at the upstream side of the check valve17.

The valve body16has a body section21screwed into the adjuster cylinder and a grease nipple section22functioning as a grease supply section at the upstream end of the body section21and positioned outside of the adjuster cylinder. This valve body16includes therein a through hole24constituting the flow path15and the through hole24is formed to penetrate both end faces. Specifically, the upstream-side opening of this through hole24is an upstream-side opening15aof the flow path15. The downstream-side opening of the through hole24is a downstream-side opening15bof the flow path15. This through hole24has, moving from the downstream side of the flow path15to the upstream side, a check valve hole part25, a communication passage26, and a foreign matter intrusion prevention valve hole part27. The check valve hole part25has the check valve17that is abutted to a valve seat31positioned at an upstream end of this check valve hole part25when in a closed state and that is moved, during the grease injection, away from the valve seat31into an open state. The communication passage26is formed to have a smaller diameter than that of the check valve hole part25and allows the check valve hole part25to communicate with the foreign matter intrusion prevention valve hole part27. The foreign matter intrusion prevention valve hole part27includes the foreign matter intrusion prevention valve18that is abutted to a valve seat33positioned at an upstream end of this foreign matter intrusion prevention valve hole part27in a closed state and that is moved, during the grease injection, away from the valve seat33to be in an open state. In this embodiment, this valve seat33is positioned at an edge of the upstream-side opening15a.

The outer periphery face of the body section21of the valve body16has threads35and36and also includes nut sections38and39provided in an integrated manner. The nut section39is provided to be adjacent to the grease nipple section22. The grease nipple section22is a part that is connected, during the grease injection, to a tip end of an injection piping having a base end connected to an injection pump (not shown).

The check valve17operates to allow grease to flow therethrough downstream while in an open condition and to regulate the grease flow upstream while in a closed state so that the grease backflow is prevented. This check valve17includes a check valve body41spherically formed of steel for example, and a compression coil spring42functioning as a check valve biasing member for biasing this check valve body41to the valve seat31.

The check valve body41is positioned at the upstream end of the check valve hole part25and is opposed to the valve seat31. The compression coil spring42is positioned at the downstream side of the check valve body41and is supported by the downstream end of the check valve hole part25.

The foreign matter intrusion prevention valve18operates to allow grease to flow therethrough while in an open state and to regulate the grease flow upstream while in a closed state to prevent grease backflow and to thereby also prevent the intrusion of foreign matter into to the flow path The term “foreign matter” means contamination of minute dirt or iron powders for example. This foreign matter intrusion prevention valve18includes a foreign matter intrusion prevention valve body44spherically formed by steel for example and a compression coil spring45that functions as a foreign matter intrusion prevention valve biasing member for biasing this foreign matter intrusion prevention valve body44to the valve seat33.

The foreign matter intrusion prevention valve body44is positioned at the upstream end of the foreign matter intrusion prevention valve hole part27and is opposed to the valve seat33. The valve body16at the periphery of this foreign matter intrusion prevention valve body44(the flow path15) includes at least one groove47. This groove47is provided to penetrate the valve seat33from the downstream side to the upstream side. Specifically, this groove47is provided to communicate with the upstream end of the flow path15(the upstream-side opening15a). As shown inFIG. 1B, a plurality of grooves47are preferably provided in the valve seat33to surround the foreign matter intrusion prevention valve body44at substantially-equal intervals. The respective grooves47are slits that are radially provided in the valve seat adjacent an outer circumference of the foreign matter intrusion prevention valve body44along the diameter direction, that have a substantially-triangular cross section having a narrower width in a direction away from the foreign matter intrusion prevention valve body44, and that have a depth in the diameter direction for example of about 0.2-0.3 mm to about 1 mm and an axial length of about 10 mm.

Returning toFIG. 1A, the compression coil spring45is positioned at the downstream side of the foreign matter intrusion prevention valve body44and is supported by the downstream end of the foreign matter intrusion prevention valve hole part27. This compression coil spring45has a biasing force set to be lower than the biasing force of the compression coil spring42of the check valve17. Thus, the foreign matter intrusion prevention valve18has a pressure resistance set to be lower than the pressure resistance of the check valve17.

INDUSTRIAL APPLICABILITY

In order to reduce the crawler tension, a desired amount of grease is discharged from a discharge valve (not shown) to the exterior of the sealed chamber of the adjuster cylinder to compress the adjuster cylinder and allow idle wheel to move in a rear direction toward the drive wheel.

In order to increase the crawler tension on the other hand, the tip end of the injection piping is connected to the grease nipple section22of the injection valve10and then the injection pump is allowed to operate. As a result, a desired amount of grease is injected through the injection valve10into the sealed chamber of the adjuster cylinder to extend the adjuster cylinder and the idle wheel is caused to move in a forward direction away from the drive wheel.

The crawler tension adjustment apparatus including the injection valve10as described above is configured so that the foreign matter intrusion prevention valve18provided in the flow path15of the valve body16of the injection valve10prevents foreign matter from intruding into the flow path15during operation of the crawler running apparatus. This can help suppress the occurrence of check valve17developing a defective valve seat and thus grease leakage and consequent loss of crawler tension, thus stabilizing the traveling performance by the crawler running apparatus.

When a malfunction of the compression coil spring42of the check valve17or a damaged valve seat causes a functional failure of the check valve, high-pressure grease may backflow to the foreign matter intrusion prevention valve hole part27from the check valve hole part25via the communication hole part26. In this case, the valve seat33provided at the upstream end of the foreign matter intrusion prevention valve hole part27of the flow path15includes the grooves47providing the communication between the downstream side of the foreign matter intrusion prevention valve body44and the upstream side. Thus, the high-pressure grease is sent through grooves47to bypass the foreign matter intrusion prevention valve body44and is discharged to the exterior of the injection valve10. This can suppress an excessive pressure due to the grease backflow from being applied to the foreign matter intrusion prevention valve18and subsequent failure of valve18, which failure might allow foreign matter to enter inject valve10and cause further damage to the crawler tension adjustment apparatus.

Furthermore, the existence of a plurality of grooves47provided to surround the foreign matter intrusion prevention valve body44at substantially-equal intervals can allow the high-pressure grease to be discharged through these grooves47in a secure and substantially-uniform manner.

In particular, the foreign matter intrusion prevention valve18has a pressure resistance set to be lower than the pressure resistance of the check valve17. Thus, although a case may be assumed where the foreign matter intrusion prevention valve18cannot sustain the pressure of backflowing grease caused by the failure of the check valve17, the grooves47can be used to discharge the high-pressure grease to the exterior. This can avoid excessive pressure during the functional failure of the check valve17from being applied to the foreign matter intrusion prevention valve18and potentially causing it to also fail, thereby maintaining the functional capability of the foreign matter intrusion prevention valve18.

In addition, the groove47is formed as a slit having a small opening area, thereby preventing foreign matter from entering the flow path through a groove47to bypass the foreign matter intrusion prevention valve18.

In the above embodiment, the crawler tension adjustment apparatus can be applied not only to a crawler running apparatus for a hydraulic shovel but also to crawler running apparatuses for other construction machines such as a bulldozer or even other grease injection valve applications.