Patent Description:
Patent Literature <NUM> discloses a telescopic boom including a plurality of boom elements in a nested structure (also referred to as a telescopic structure), and a mobile crane including a hydraulic telescopic cylinder for extending the telescopic boom.

Patent Literature <NUM> and <NUM> disclose a crane, respectively. In particular, the crane disclosed in Patent Literature <NUM> include a telescopic boom, an extension device, a hydraulic pressure source, a cylinder connection mechanism, and an oil path. The telescopic boom is capable of being extended. The extension device extends the telescopic boom. The hydraulic pressure source is provided in the extension device. The cylinder connection mechanism is connected to the hydraulic pressure source and switching between states of connection and non-connection with the telescopic boom. The oil path connects the hydraulic pressure source and the cylinder connection mechanism. This document discloses the features of the preamble of claim <NUM>.

The telescopic boom includes boom connection pins that connect adjacent and overlapping boom elements. The boom element connection of which by the boom connection pins (hereinafter referred to as the displaceable boom element) has been released becomes displaceable in a longitudinal direction (also referred to as an extension/contraction direction) with respect to another boom element.

The telescopic cylinder includes a rod member and a cylinder member. Such a telescopic cylinder has the cylinder member connected to the displaceable boom element using cylinder connection pins. Displacement of the cylinder member in the extension/contraction direction in this state leads to the displacement of the displaceable boom element together with the cylinder member, resulting in extension/contraction of the telescopic boom.

The crane as described above includes a hydraulic actuator that displaces the cylinder connection pins and a hydraulic circuit that supplies pressure oil to the actuator. Such a hydraulic circuit includes a valve for switching between supply and discharge of hydraulic oil to and from the actuator. If such a valve becomes inoperable, the actuator cannot be operated.

An object of the present invention is to provide a crane in which an actuator that displaces cylinder connection pins can be operated even when a valve that switches between supply and discharge of hydraulic oil to and from the actuator becomes inoperable.

The present invention provides a crane according to independent claim <NUM>.

<FIG> and <FIG> show second and third embodiments respectively that are described in the description but are not part of the claimed invention.

The present invention provides a crane in which an actuator that displaces cylinder connection pins can be operated even when a valve becomes inoperable.

Some examples of embodiments according to the present invention are described in detail below with reference to the drawings. It should be noted that each embodiment described below is an example of a crane according to the present invention, and the present invention is not limited to each embodiment.

<FIG> is a schematic view of a mobile crane <NUM> (rough terrain crane in the illustrated case) according to the present embodiment.

Examples of the mobile crane include an all-terrain crane, a truck cranes, and a truck loader crane (also referred to as a cargo crane). However, the crane according to the present invention is not limited to a mobile crane, and can be applied to other cranes having a telescopic boom.

Hereinafter, first of all, the mobile crane <NUM> and a telescopic boom <NUM> of the mobile crane <NUM> will be described. Then, the description will be given on the specific structure and operation of a hydraulic mechanism <NUM> (see <FIG>) for operating a cylinder connection mechanism <NUM> and a boom connection mechanism <NUM>, which are the features of the mobile crane <NUM> according to the present embodiment.

The mobile crane <NUM> illustrated in <FIG> includes a traveling body <NUM>, outriggers <NUM>, a swivel base <NUM>, the telescopic boom <NUM>, an actuator A (see <FIG>), a derricking cylinder <NUM>, a wire rope <NUM>, and a hook <NUM>.

The traveling body <NUM> has a plurality of wheels <NUM>. The outriggers <NUM> are provided at the four corners of the traveling body <NUM>. The swivel base <NUM> is provided on an upper portion of the traveling body <NUM> so as to be swivelable. The telescopic boom <NUM> has a base end portion fixed to the swivel base <NUM>. The actuator A extends and contracts the telescopic boom <NUM>. The derricking cylinder <NUM> moves the telescopic boom <NUM> upward and downward. The wire rope <NUM> hangs from a distal end portion of the telescopic boom <NUM>. The hook <NUM> is provided at the distal end of the wire rope <NUM>.

Next, the telescopic boom <NUM> will be described with reference to <FIG> and <FIG> are schematic views for explaining the structure and extension/contraction operation of the telescopic boom <NUM>.

<FIG> illustrates the telescopic boom <NUM> in an extension state. <FIG> illustrates the telescopic boom <NUM> in a contraction state. <FIG> illustrates the telescopic boom <NUM> in which only a distal end boom element <NUM>, which will be described later, is extended.

The telescopic boom <NUM> includes a plurality (at least a pair) of boom elements. The plurality of boom elements each have a tubular shape and are telescopically combined. Specifically, in the contraction state, the plurality of boom elements have the distal end boom element <NUM>, an intermediate boom element <NUM>, and a base end boom element <NUM> in this order from the inner side.

In the case of the present embodiment, the distal end boom element <NUM> and the intermediate boom element <NUM> are boom elements that are displaceable in the extension/contraction direction. On the other hand, the base end boom element <NUM> is a boom element whose displacement in the extension/contraction direction is regulated.

The telescopic boom <NUM> transitions from the contraction state illustrated in <FIG> to the extension state illustrated in <FIG> by extending in order from the boom element arranged on the inner side (that is, the distal end boom element <NUM>).

In the extension state, the intermediate boom element <NUM> is arranged between the base end boom element <NUM> on the most base end side and the distal end boom element <NUM> on the most distal end side. There may be a plurality of intermediate boom elements.

The telescopic boom <NUM> is substantially the same as the conventionally known telescopic boom, but for convenience of description of the actuator A described later, the distal end boom element <NUM> and the intermediate boom element <NUM> will be described below.

The distal end boom element <NUM> has a tubular shape and has an internal space that can accommodate the actuator A. The distal end boom element <NUM> includes a pair of cylinder pin receiving portions 141a and a pair of boom pin receiving portions 141b at the base end portion.

The pair of cylinder pin receiving portions 141a are formed coaxially with each other at the base end portion of the distal end boom element <NUM>. Each of the pair of cylinder pin receiving portions 141a can be engaged with and disengaged from (that is, in either an engaged state or a disengaged state) a pair of cylinder connection pins <NUM> provided on a cylinder member <NUM> of a telescopic cylinder <NUM>. The pair of cylinder connection pins <NUM> are each urged in a direction of engaging with the pair of cylinder pin receiving portions 141a by, for example, a spring (not illustrated).

Each of the pair of cylinder connection pins <NUM> is displaced in its own axial direction based on the operation of the cylinder connection mechanism <NUM> included in the actuator A. With the pair of cylinder connection pins <NUM> and the pair of cylinder pin receiving portions 141a engaged, the distal end boom element <NUM> is displaceable in the extension/contraction direction together with the cylinder member <NUM>.

The pair of boom pin receiving portions 141b are formed coaxially with each other closer to the base end in the distal end boom element <NUM> than the cylinder pin receiving portions 141a are. The pair of boom pin receiving portions 141b can be engaged with and detached from a pair of boom connection pins 51a.

The pair of boom connection pins 51a each connect the distal end boom element <NUM> and the intermediate boom element <NUM>. Each of the pair of boom connection pins 51a is displaced in its own axial direction based on the operation of the boom connection mechanism <NUM> included in the actuator A.

With the distal end boom element <NUM> and the intermediate boom element <NUM> connected by the pair of boom connection pins 51a, the boom connection pins 51a are inserted across the boom pin receiving portions 141b of the distal end boom element <NUM> and first boom pin receiving portions 142b or second boom pin receiving portions 142c of the intermediate boom element <NUM> described later. The pair of boom connection pins 51a are each urged in a direction of engaging with the first boom pin receiving portions 142b by, for example, a spring (not illustrated).

With the distal end boom element <NUM> and the intermediate boom element <NUM> connected (also referred to as a state of connection), the distal end boom element <NUM> cannot be displaced with respect to the intermediate boom element <NUM> in the extension/contraction direction.

On the other hand, with the distal end boom element <NUM> and the intermediate boom element <NUM> disconnected (also referred to as a state of non-connection), the distal end boom element <NUM> is displaceable with respect to the intermediate boom element <NUM> in the extension/contraction direction.

The intermediate boom element <NUM> has a tubular shape as illustrated in <FIG>, and has an internal space that can accommodate the distal end boom element <NUM>. The intermediate boom element <NUM> includes a pair of cylinder pin receiving portions 142a, the pair of first boom pin receiving portions 142b, and a pair of third boom pin receiving portions 142d at the base end portion.

The pair of cylinder pin receiving portions 142a and the pair of first boom pin receiving portions 142b are substantially the same as the pair of cylinder pin receiving portions 141a and the pair of boom pin receiving portions 141b of the distal end boom element <NUM>, respectively.

The pair of third boom pin receiving portions 142d are formed coaxially with each other closer to the base end in the intermediate boom element <NUM> than the pair of first boom pin receiving portions 142b are. Boom connection pins 51b can be inserted into the pair of respective third boom pin receiving portions 142d. The boom connection pins 51b connect the intermediate boom element <NUM> and the base end boom element <NUM>. The pair of boom connection pins 51b are each urged in a direction of engaging with the first boom pin receiving portions 142b by, for example, a spring (not illustrated).

Furthermore, the intermediate boom element <NUM> includes the pair of second boom pin receiving portions 142c at the distal end portion. The pair of second boom pin receiving portions 142c are formed coaxially with each other at the distal end portion of the intermediate boom element <NUM>. The pair of boom connection pins 51a can be inserted into each of the pair of respective second boom pin receiving portions 142c.

The actuator A as described above extends and contracts the telescopic boom <NUM> (see <FIG>, <FIG>). The actuator A includes, for example, the telescopic cylinder <NUM> (also referred to as an extension device) that displaces the distal end boom element <NUM> among the adjacent and overlapping distal end boom element <NUM> (also referred to as an inner boom element) and intermediate boom element <NUM> (also referred to as an outer boom element) in the extension/contraction direction, an accumulator 602A (also referred to as a hydraulic pressure source, see <FIG>) provided in the telescopic cylinder <NUM>, the cylinder connection mechanism <NUM> (see <FIG>) that switches between states of connection and non-connection between the telescopic cylinder <NUM> and the distal end boom element <NUM> by displacing the pair of cylinder connection pins <NUM> based on the supply and discharge of hydraulic oil, and the boom connection mechanism <NUM> (see <FIG>) that switches between states of connection and non-connection between the distal end boom element <NUM> and the intermediate boom element <NUM> by displacing the pair of boom connection pins 51a based on the supply and discharge of hydraulic oil.

The telescopic cylinder <NUM> includes a rod member <NUM> (also referred to as a fixed side member, see <FIG>) and the cylinder member <NUM> (also referred to as a movable side member). This telescopic cylinder <NUM> displaces a boom element (for example, the distal end boom element <NUM> or the intermediate boom element <NUM>) connected to the cylinder member <NUM> via the cylinder connection pins <NUM> described later in the extension/contraction direction.

As illustrated in <FIG>, this telescopic cylinder <NUM> includes a contraction side hydraulic chamber <NUM> and an extension side hydraulic chamber <NUM> in the internal space of the cylinder member <NUM>. The contraction side hydraulic chamber <NUM> and the extension side hydraulic chamber <NUM> are each connected to a hydraulic pump (not illustrated) that is driven based on the driving force of an engine (not illustrated). When hydraulic oil is supplied from the hydraulic pump to the extension side hydraulic chamber <NUM>, the telescopic cylinder <NUM> extends. When hydraulic oil is supplied from the hydraulic pump to the contraction side hydraulic chamber <NUM>, the telescopic cylinder <NUM> contracts. Since the structure of the telescopic cylinder <NUM> is almost the same as that of a conventionally known telescopic cylinder, any further detailed description thereof will be omitted.

The cylinder connection mechanism <NUM> transitions between an extension state and a contraction state based on the supply and discharge of hydraulic oil to the hydraulic chamber <NUM> (see <FIG>). Specifically, the cylinder connection mechanism <NUM> is in the contraction state when hydraulic oil is supplied to the hydraulic chamber <NUM>. On the other hand, the cylinder connection mechanism <NUM> is in the extension state when hydraulic oil is discharged from the hydraulic chamber <NUM>.

In the extension state of the cylinder connection mechanism <NUM>, the pair of cylinder connection pins <NUM> and the pair of cylinder pin receiving portions 141a of the boom element (for example, the distal end boom element <NUM>) are in an engaged state (also referred to as a cylinder pin engaged state). In the engaged state, the boom element and the cylinder member <NUM> are in the state of connection.

On the other hand, in the contraction state of the cylinder connection mechanism <NUM>, the pair of cylinder connection pins <NUM> and the pair of cylinder pin receiving portions 141a (see <FIG>) are in a disengaged state (the state illustrated in <FIG>, and also referred to as a cylinder pin disengaged state). In the disengaged state, the boom element and the cylinder member <NUM> are in the state of non-connection.

In the following description, the operation when the cylinder connection mechanism <NUM> transitions from the extension state to the contraction state is referred to as a disengaging operation of the cylinder connection mechanism <NUM>. The cylinder connection mechanism <NUM> displaces the pair of cylinder connection pins <NUM> against the elastic force of a spring (not illustrated) in the disengaging operation. Furthermore, the operation when the cylinder connection mechanism <NUM> transitions from the contraction state to the extension state is referred to as an engaging operation of the cylinder connection mechanism <NUM>. Since the structure of this cylinder connection mechanism <NUM> is the same as that of a conventionally known structure, any further detailed description thereof will be omitted.

The boom connection mechanism <NUM> transitions between the extension state and the contraction state based on the supply and discharge of hydraulic oil to the hydraulic chamber <NUM> (see <FIG>). Specifically, the boom connection mechanism <NUM> is in the contraction state when hydraulic oil is supplied to the hydraulic chamber <NUM>. On the other hand, the boom connection mechanism <NUM> is in the extension state when hydraulic oil is discharged from the hydraulic chamber <NUM>.

In the extension state, the boom connection mechanism <NUM> takes either an engaged state with or a disengaged state from boom connection pins (for example, the pair of boom connection pins 51a).

The boom connection mechanism <NUM> disengages boom connection pins (for example, the pair of boom connection pins 51a) from a boom element (for example, the first boom pin receiving portions 142b of the intermediate boom element <NUM>) by transitioning from the extension state to the contraction state while being engaged with the boom connection pins (see <FIG>).

Furthermore, the boom connection mechanism <NUM> engages the boom connection pins with the boom element by transitioning from the contraction state to the extension state while being engaged with the boom connection pins.

In the following description, the operation when the boom connection mechanism <NUM> transitions from the extension state to the contraction state is referred to as a disengaging operation of the boom connection mechanism. The boom connection mechanism <NUM> displaces the pair of boom connection pins 51a or the pair of boom connection pins 51b against the elastic force of a spring (not illustrated) in the disengaging operation. Furthermore, the operation when the boom connection mechanism <NUM> transitions from the contraction state to the extension state is referred to as an engaging operation of the boom connection mechanism. Since the structure of this boom connection mechanism <NUM> is the same as that of a conventionally known structure, any further detailed description thereof will be omitted.

Next, the hydraulic mechanism <NUM> for driving the cylinder connection mechanism <NUM> and the boom connection mechanism <NUM> will be described with reference to <FIG>.

The hydraulic mechanism <NUM> includes a cylinder side hydraulic pressure source <NUM>, the accumulator 602A, a hydraulic pressure switching mechanism <NUM>, a first solenoid valve <NUM>, and a second solenoid valve <NUM>. This hydraulic mechanism <NUM> is provided in the telescopic cylinder <NUM> (specifically, the cylinder member <NUM>; see <FIG> for the cylinder member <NUM>). Therefore, the hydraulic mechanism <NUM> is displaceable together with the cylinder member <NUM>.

These configurations are connected through individual oil paths described later. In particular, in the case of the present embodiment, the hydraulic mechanism <NUM> includes a normal oil path that is an oil path for hydraulic oil in a normal time and an emergency oil path that is an oil path for hydraulic oil in an emergency. The normal oil path is an oil path through which hydraulic oil flows in the cases of operation examples <NUM>-<NUM> to operation examples <NUM>-<NUM>, which will be described later. The emergency oil path is an oil path through which hydraulic oil flows in the case of operation example <NUM>-<NUM>, which will be described later. The normal oil path and the emergency oil path will be described later.

The cylinder side hydraulic pressure source <NUM> is composed of a contraction side hydraulic chamber <NUM> in the cylinder member <NUM> of the telescopic cylinder <NUM>.

The accumulator 602A is a hydraulic pressure source that boosts and stores hydraulic oil supplied from the cylinder side hydraulic pressure source <NUM>.

The cylinder side hydraulic pressure source <NUM> and the accumulator 602A are connected through an oil path element L2. In the following description, the upstream side means the side closer to the hydraulic pressure source (the cylinder side hydraulic pressure source <NUM> or the accumulator 602A) in the oil path for hydraulic oil unless otherwise specified. The downstream side means the side closer to the cylinder connection mechanism <NUM> or the boom connection mechanism <NUM> in the oil path for hydraulic oil unless otherwise specified. In the following description, the upstream end of each oil path element may be replaced with one end, and the downstream end thereof may be replaced with the other end.

The oil path element L2 includes an upstream oil path element L21 on the upstream side (the side closer to the cylinder side hydraulic pressure source <NUM>) of a branch point X, and a downstream oil path element L22 on the downstream side (the side away from the cylinder side hydraulic pressure source <NUM>) of the branch point X. The downstream end of the downstream oil path element L22 is connected to an input port of the accumulator 602A. The upstream oil path element L22 is provided with a check valve 606a. The configuration of the oil path element L2 is not limited to the one illustrated in the figure.

The hydraulic pressure switching mechanism <NUM> includes a hydraulic pressure switching valve 603a and a pilot solenoid valve 603b. The hydraulic pressure switching mechanism <NUM> is for supplying hydraulic oil supplied from a hydraulic pressure source (the accumulator 602A in the case of the present embodiment) to an oil path element L7 (bypass oil path), which will be described later, in an emergency.

The hydraulic pressure switching valve 603a is a second valve. A downstream end of an oil path element L3 is connected to a first port of this hydraulic pressure switching valve 603a. An upstream end of the oil path element L3 is connected to an output port of the accumulator 602A. The hydraulic pressure switching valve 603a is connected to the accumulator 602A via the oil path element L3. The oil path element L3 is provided with a pressure reducing valve 609a. The configuration of the oil path element L3 is not limited to the one illustrated in the figure.

An upstream end of an oil path element L4 is connected to a second port of the hydraulic pressure switching valve 603a. A downstream end of the oil path element L4 is connected to the first solenoid valve <NUM>. The hydraulic pressure switching valve 603a is connected to the first solenoid valve <NUM> via the oil path element L4. The configuration of the oil path element L4 is not limited to the one illustrated in the figure.

An upstream end of an oil path element L5 is connected to a third port of the hydraulic pressure switching valve 603a. A downstream end of the oil path element L5 is connected to the first solenoid valve <NUM>. The hydraulic pressure switching valve 603a is connected to the first solenoid valve <NUM> via the oil path element L5. The configuration of the oil path element L5 is not limited to the one illustrated in the figure.

A downstream end of an oil path element L6 is connected to a fourth port of the hydraulic pressure switching valve 603a. An upstream end of the oil path element L6 is connected to the upstream oil path element L21 via the branch point X. The hydraulic pressure switching valve 603a is connected to the cylinder side hydraulic pressure source <NUM> via the oil path element L6 and the upstream oil path element L21. The configuration of the oil path element L6 is not limited to the one illustrated in the figure.

The oil path element L6 is provided with a check valve 606b. The check valve 606b allows the flow of hydraulic oil from the downstream side to the upstream side. On the other hand, the check valve 606b blocks the flow of hydraulic oil from the upstream side to the downstream side. The configuration of the oil path element L6 is not limited to the one illustrated in the figure.

An upstream end of an oil path element L7 is connected to a fifth port of the hydraulic pressure switching valve 603a. The oil path element L7 is a bypass oil path that bypasses the first solenoid valve <NUM>. A downstream end of the oil path element L7 is connected to an oil path element L12 described later. The oil path element L7 is provided with a check valve 606d. The check valve 606d allows the flow of hydraulic oil from the upstream side to the downstream side. On the other hand, the check valve 606d blocks the flow of hydraulic oil from the downstream side to the upstream side. The configuration of the oil path element L7 is not limited to the one illustrated in the figure.

A downstream end of an oil path element L8 is connected to a sixth port of the hydraulic pressure switching valve 603a. An upstream end of the oil path element L8 is connected to the upstream oil path element L21 via the branch point X. The hydraulic pressure switching valve 603a is connected to the cylinder side hydraulic pressure source <NUM> via the oil path element L8 and the upstream oil path element L21. The configuration of the oil path element L8 is not limited to the one illustrated in the figure.

A downstream end of an oil path element L9 is connected to a seventh port (pilot port) of the hydraulic pressure switching valve 603a. An upstream end of the oil path element L9 is connected to the pilot solenoid valve 603b. The hydraulic pressure switching valve 603a is connected to the pilot solenoid valve 603b via the oil path element L9. The configuration of the oil path element L9 is not limited to the one illustrated in the figure.

The pilot solenoid valve 603b (also referred to as a third valve) supplies hydraulic oil from the cylinder side hydraulic pressure source <NUM> to the seventh port (pilot port) of the hydraulic pressure switching valve 603a as a pilot pressure in an energized state. On the other hand, the pilot solenoid valve 603b stops supplying the hydraulic oil (pilot pressure) to the hydraulic pressure switching valve 603a in a non-energized state.

A downstream end of an oil path element L10 is connected to a first port of this pilot solenoid valve 603b. An upstream end of the oil path element L10 is connected to the oil path element L8. The configuration of the oil path element L10 is not limited to the one illustrated in the figure.

A downstream end of an oil path element L11 is connected to a second port of the pilot solenoid valve 603b. An upstream end of the oil path element L11 is connected to the oil path element L6. Hydraulic oil discharged from the second port of the pilot solenoid valve 603b returns to the cylinder side hydraulic pressure source <NUM> via the oil path element L11, the oil path element L6, and the upstream oil path element L21.

The upstream end of the oil path element L9 is connected to a third port of the pilot solenoid valve 603b. In the energized state, the pilot solenoid valve 603b supplies hydraulic oil supplied from the cylinder side hydraulic pressure source <NUM> to the hydraulic pressure switching valve 603a via the oil path element L9.

The hydraulic pressure switching valve 603a constituting the hydraulic pressure switching mechanism <NUM> as described above opens the second port and the third port of the hydraulic pressure switching valve 603a and closes the fifth port thereof in a first state. Thus, the hydraulic pressure switching valve 603a permits the flow of hydraulic oil between the hydraulic pressure switching valve 603a and the first solenoid valve <NUM> in the first state. Furthermore, the hydraulic pressure switching valve 603a blocks the flow of hydraulic oil between the hydraulic pressure switching valve 603a and the oil path element L7 in the first state.

On the other hand, the hydraulic pressure switching valve 603a closes the second port and the third port of the hydraulic pressure switching valve 603a and opens the fifth port thereof in a second state. Thus, the hydraulic pressure switching valve 603a blocks the flow of hydraulic oil between the hydraulic pressure switching valve 603a and the first solenoid valve <NUM> in the second state. Furthermore, the hydraulic pressure switching valve 603a permits the flow of hydraulic oil between the oil path element L3 and the oil path element L7 in the second state.

In the case of the present embodiment, the hydraulic pressure switching valve 603a is in the first state when the pilot solenoid valve 603b is in the energized state, and is in the second state when the pilot solenoid valve 603b is in the non-energized state.

The first solenoid valve <NUM> switches between the first state that allows the flow of hydraulic oil from the upstream side to the downstream side and the second state that allows the flow of hydraulic oil from the downstream side to the upstream side in response to energization. In the case of the present embodiment, the first solenoid valve <NUM> is in the first state when it is in the energized state, and is in the second state when it is in the non-energized state.

The first solenoid valve <NUM> blocks the flow of hydraulic oil from the downstream side to the upstream side in the first state. On the other hand, the first solenoid valve <NUM> blocks the flow of hydraulic oil from the upstream side to the downstream side in the second state.

Specifically, the downstream end of the oil path element L4 is connected to a first port of the first solenoid valve <NUM>. The first solenoid valve <NUM> is connected to the hydraulic pressure switching valve 603a via the oil path element L4.

An upstream end of the oil path element L12 is connected to a second port of the first solenoid valve <NUM>. A downstream end of the oil path element L12 is connected to the second solenoid valve <NUM>. The first solenoid valve <NUM> is connected to the second solenoid valve <NUM> via the oil path element L12. The configuration of the oil path element L12 is not limited to the one illustrated in the figure.

The downstream end of the oil path element L5 is connected to a third port of the first solenoid valve <NUM>. The first solenoid valve <NUM> is connected to the hydraulic pressure switching valve 603a via the oil path element L5.

This first solenoid valve <NUM> permits the flow of hydraulic oil between the oil path element L4 and the oil path element L12 in the first state (energized state). On the other hand, the first solenoid valve <NUM> blocks the flow of hydraulic oil between the oil path element L5 and the oil path element L12 in the first state. Specifically, the first solenoid valve <NUM> can supply hydraulic oil supplied from the oil path element L4 to the oil path element L12 in the first state.

On the other hand, the first solenoid valve <NUM> permits the flow of hydraulic oil between the oil path element L5 and the oil path element L12 in the second state. The first solenoid valve <NUM> blocks the flow of hydraulic oil between the oil path element L4 and the oil path element L12 in the second state. Specifically, the first solenoid valve <NUM> can supply hydraulic oil supplied from the oil path element L12 to the hydraulic pressure switching valve 603a via the oil path element L5 in the second state.

The second solenoid valve <NUM> switches between the first state in which hydraulic oil supplied from the upstream side is supplied to the hydraulic chamber <NUM> of the boom connection mechanism <NUM> and the second state in which the hydraulic oil supplied from the upstream side is supplied to the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> in response to energization. In the case of the present embodiment, the second solenoid valve <NUM> is in the first state when it is in the energized state, and is in the second state when it is in the non-energized state.

The second solenoid valve <NUM> prevents the hydraulic oil supplied from the upstream side from flowing into the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> in the first state. On the other hand, the second solenoid valve <NUM> prevents the hydraulic oil supplied from the upstream side from flowing into the hydraulic chamber <NUM> of the boom connection mechanism <NUM> in the second state.

Specifically, the downstream end of the oil path element L12 is connected to a first port of the second solenoid valve <NUM>.

An upstream end of an oil path element L13 is connected to a second port of the second solenoid valve <NUM>. A downstream end of the oil path element L13 is connected to the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM>. The second solenoid valve <NUM> is connected to the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> via the oil path element L13. The configuration of the oil path element L13 is not limited to the one illustrated in the figure.

An upstream end of an oil path element L14 is connected to a third port of the second solenoid valve <NUM>. A downstream end of the oil path element L14 is connected to the hydraulic chamber <NUM> of the boom connection mechanism <NUM>. The second solenoid valve <NUM> is connected to the hydraulic chamber <NUM> of the boom connection mechanism <NUM> via the oil path element L14.

This second solenoid valve <NUM> allows the flow of hydraulic oil between the oil path element L12 and the oil path element L14 in the first state (that is, the energized state). That is, the second solenoid valve <NUM> can supply the hydraulic oil supplied from the oil path element L12 to the hydraulic chamber <NUM> of the boom connection mechanism <NUM> via the oil path element L14 in the first state.

On the other hand, the second solenoid valve <NUM> allows the flow of hydraulic oil between the oil path element L12 and the oil path element L13 in the second state (that is, the non-energized state). That is, the second solenoid valve <NUM> can supply the hydraulic oil supplied from the oil path element L12 to the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> via the oil path element L13 in the second state.

Next, the operation of the hydraulic mechanism <NUM> will be described with reference to <FIG>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism <NUM> in performing the disengaging operation of the boom connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism <NUM> in performing the engaging operation of the boom connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism <NUM> in performing the disengaging operation of the cylinder connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism <NUM> in performing the engaging operation of the cylinder connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism <NUM> in performing the disengaging operation of the cylinder connection mechanism <NUM> in an emergency.

In the following description, it is assumed that the accumulator 602A has accumulated sufficient hydraulic oil to perform each of these operations.

First, the operation of the hydraulic mechanism <NUM> in performing the disengaging operation of the boom connection mechanism <NUM> will be described with reference to <FIG>. Since the configuration of each member in the hydraulic mechanism <NUM> is as described above, any overlapping description will be omitted.

For example, if an operator instructs the disengaging operation of the boom connection mechanism <NUM> in the state in which the distal end boom element <NUM> and the intermediate boom element <NUM> are connected (see <FIG>), the first solenoid valve <NUM>, the pilot solenoid valve 603b, and the second solenoid valve <NUM> become the energized state.

As a result, the first solenoid valve <NUM>, the hydraulic pressure switching valve 603a, and the second solenoid valve <NUM> each become the first state. Then, hydraulic oil discharged from the accumulator 602A is supplied to the hydraulic chamber <NUM> of the boom connection mechanism <NUM> through the oil path illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a feed oil path in the normal oil path. The feed oil path means an oil path through which hydraulic oil flows from a hydraulic pressure source (the accumulator 602A in the case of this operation example) to the cylinder connection mechanism <NUM> or the boom connection mechanism <NUM>.

Specifically, the hydraulic oil flows through the accumulator 602A, the oil path element L3, the hydraulic pressure switching valve 603a, the oil path element L4, the first solenoid valve <NUM>, the oil path element L12, the second solenoid valve <NUM>, the oil path element L14, and the hydraulic chamber <NUM> of the boom connection mechanism <NUM> in this order.

As a result, the boom connection mechanism <NUM> transitions from the extension state to the contraction state, and the boom connection pins 51a are disengaged from the first boom pin receiving portions 142b or the second boom pin receiving portions 142c of the intermediate boom element <NUM>. In this case, as an example, the boom connection pins 51a transition from the state illustrated in <FIG> to the state illustrated in <FIG>.

Next, the operation of the hydraulic mechanism <NUM> in performing the engaging operation of the boom connection mechanism <NUM> will be described with reference to <FIG>.

For example, if the operator instructs the engaging operation of the boom connection mechanism <NUM> in the state in which the distal end boom element <NUM> and the intermediate boom element <NUM> are not connected (see <FIG>), the second solenoid valve <NUM> and the pilot solenoid valve 603b become the energized state, whereas the first solenoid valve <NUM> becomes the non-energized state.

As a result, the second solenoid valve <NUM> and the hydraulic pressure switching valve 603a become the first state, whereas the first solenoid valve <NUM> becomes the second state. Then, hydraulic oil in the hydraulic chamber <NUM> of the boom connection mechanism <NUM> returns to the cylinder side hydraulic pressure source <NUM> through the oil path illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a return oil path in the normal oil path. The return oil path means an oil path through which hydraulic oil flows from the cylinder connection mechanism <NUM> or the boom connection mechanism <NUM> to a hydraulic pressure source (the cylinder side hydraulic pressure source <NUM> in the case of this operation example).

Specifically, the hydraulic oil flows through the hydraulic chamber <NUM> of the boom connection mechanism <NUM>, the oil path element L14, the second solenoid valve <NUM>, the oil path element L12, the first solenoid valve <NUM>, the oil path element L5, the hydraulic pressure switching valve 603a, the oil path element L6, the upstream oil path element L21, and the cylinder side hydraulic pressure source <NUM> in this order.

As a result, the boom connection mechanism <NUM> transitions from the extension state to the contraction state, and the boom connection pins 51a are inserted across the boom pin receiving portions 141b of the distal end boom element <NUM> and the first boom pin receiving portions 142b (or the second boom pin receiving portions 142c) of the intermediate boom element <NUM>. In this case, as an example, the boom connection pins 51a transition from the state illustrated in <FIG> to the state illustrated in <FIG>.

Next, the operation of the hydraulic mechanism <NUM> in performing the disengaging operation of the cylinder connection mechanism <NUM> will be described with reference to <FIG>.

For example, if the operator instructs the disengaging operation of the cylinder connection mechanism <NUM> in the state of connection between the distal end boom element <NUM> and the cylinder member <NUM> as illustrated in <FIG>, the first solenoid valve <NUM> and the pilot solenoid valve 603b become the energized state, whereas the second solenoid valve <NUM> becomes the non-energized state.

As a result, the first solenoid valve <NUM> and the hydraulic pressure switching valve 603a become the first state, whereas the second solenoid valve <NUM> becomes the second state. Then, the hydraulic oil discharged from the accumulator 602A is supplied to the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> through the oil path (also referred to as a first oil path) illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a feed oil path in the normal oil path.

Specifically, the hydraulic oil flows through the accumulator 602A, the oil path element L3, the hydraulic pressure switching valve 603a, the oil path element L4, the first solenoid valve <NUM>, the oil path element L12, the second solenoid valve <NUM>, the oil path element L13, and the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> in this order.

As a result, the cylinder connection mechanism <NUM> transitions from the extension state to the contraction state, and the pair of cylinder connection pins <NUM> are disengaged from the cylinder pin receiving portions 141a of the distal end boom element <NUM>. That is, the pair of cylinder connection pins <NUM> transition from the state illustrated in <FIG> to the state illustrated in <FIG>.

Next, the operation of the hydraulic mechanism <NUM> in performing the engaging operation of the cylinder connection mechanism <NUM> will be described with reference to <FIG>.

For example, if the operator instructs the engaging operation of the cylinder connection mechanism <NUM> in the state of non-connection between the distal end boom element <NUM> and the cylinder member <NUM> as illustrated in <FIG>, the pilot solenoid valve 603b becomes the energized state, whereas the first solenoid valve <NUM> and the second solenoid valve <NUM> become the non-energized state.

As a result, the hydraulic pressure switching valve 603a becomes the first state, whereas the first solenoid valve <NUM> and the second solenoid valve <NUM> become the second state. Then, hydraulic oil in the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> returns to the cylinder side hydraulic pressure source <NUM> through the oil path illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a return oil path in the normal oil path.

Specifically, the hydraulic oil flows through the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM>, the oil path element L13, the second solenoid valve <NUM>, the oil path element L12, the first solenoid valve <NUM>, the oil path element L5, the hydraulic pressure switching valve 603a, the oil path element L6, the upstream oil path element L21, and the cylinder side hydraulic pressure source <NUM> in this order.

As a result, the cylinder connection mechanism <NUM> transitions from the contraction state to the extension state, and the pair of cylinder connection pins <NUM> are inserted into the cylinder pin receiving portions 141a of the distal end boom element <NUM>. In this case, as an example, the pair of cylinder connection pins <NUM> transition from the state illustrated in <FIG> to the state illustrated in <FIG>.

Next, the operation of the hydraulic mechanism <NUM> in performing the disengaging operation of the cylinder connection mechanism <NUM> in an emergency will be described with reference to <FIG>. In the present embodiment, the term "emergency" means a situation in which the first solenoid valve <NUM>, the pilot solenoid valve 603b, and the second solenoid valve <NUM> cannot be energized and the switching of these valves cannot be performed. Causes of such an emergency include failure of the first solenoid valve <NUM>, the pilot solenoid valve 603b, or the second solenoid valve <NUM>, disconnection of the wiring (cord reel) that supplies power to each of these valves, and the like.

For example, the operator instructs the disengaging operation of the cylinder connection mechanism <NUM> in an emergency through a predetermined operation (a switch operation, for example) if the first solenoid valve <NUM>, the pilot solenoid valve 603b, and the second solenoid valve <NUM> cannot be energized in the state of connection between the distal end boom element <NUM> and the cylinder member <NUM> as illustrated in <FIG>.

With the telescopic cylinder <NUM> (see <FIG>) transitioning in the contraction direction in response to the above-described instruction, hydraulic oil is supplied from the cylinder side hydraulic pressure source <NUM> via the upstream oil path element L21 and the oil path element L8 to the sixth port of the hydraulic pressure switching valve 603a. Then, the hydraulic pressure switching valve 603a transitions from the first state to the second state. In this state, the hydraulic pressure switching valve 603a permits the flow of hydraulic oil between the oil path element L3 and the oil path element L7 (bypass oil path).

As a result, the hydraulic oil discharged from the accumulator 602A is supplied to the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> through the oil path (also referred to as a second oil path) illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a feed oil path in the emergency oil path.

Specifically, the hydraulic oil flows through the accumulator 602A, the oil path element L3, the hydraulic pressure switching valve 603a, the oil path element L7 (bypass oil path), the oil path element L12, the second solenoid valve <NUM>, the oil path element L13, and the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> in this order.

As a result, the cylinder connection mechanism <NUM> transitions from the extension state to the contraction state, and the pair of cylinder connection pins <NUM> are disengaged from the cylinder pin receiving portions 141a of the distal end boom element <NUM>. In this case, as an example, the pair of cylinder connection pins <NUM> transition from the state illustrated in <FIG> to the state illustrated in <FIG>.

As described above, according to the present embodiment, the cylinder pins (specifically, the pair of cylinder connection pins <NUM>) can be disengaged from boom elements (for example, the cylinder pin receiving portions 141a of the distal end boom element <NUM>) (see <FIG>) in an emergency in which the first solenoid valve <NUM>, the pilot solenoid valve 603b, and the second solenoid valve <NUM> cannot be energized and the switching of these valves cannot be performed. As a result, the telescopic cylinder <NUM> can contract in an emergency.

A second embodiment (non-claimed) will be described with reference to <FIG> tc 4E. In the case of the present embodiment, the configuration of a hydraulic mechanism 6B is different from that in the above-described first embodiment. The configurations of the other parts are the same as those in the first embodiment. Hereinafter, the hydraulic mechanism 6B will be described.

The hydraulic mechanism 6B includes the cylinder side hydraulic pressure source <NUM>, the accumulator 602A, a first solenoid valve 604B, the second solenoid valve <NUM>, and an emergency switching mechanism <NUM>.

The cylinder side hydraulic pressure source <NUM>, the accumulator 602A, and the second solenoid valve <NUM> are the same as those in the first embodiment described above.

In the case of the present embodiment, a counterbalance valve 601a is provided in an oil path element L1a connecting the extension side hydraulic chamber <NUM> and a hydraulic pump (not illustrated) that is driven based on the driving force of an engine (not illustrated). The counterbalance valve 601a prevents the cylinder member <NUM> of the telescopic cylinder <NUM> from being pushed back by load applied from the telescopic boom <NUM> (see <FIG>, <FIG>).

To this counterbalance valve 601a, the hydraulic pressure of an oil path element L1b connecting the contraction side hydraulic chamber <NUM> and the hydraulic pump is applied as a pilot pressure via an oil path element L1c. The counterbalance valve 601a always allows the flow of hydraulic oil from the hydraulic pump to the extension side hydraulic chamber <NUM>.

Furthermore, the counterbalance valve 601a basically prevents hydraulic oil discharged from the extension side hydraulic chamber <NUM> from passing therethrough. The counterbalance valve 601a however allows the hydraulic oil discharged from the extension side hydraulic chamber <NUM> to pass therethrough only when the hydraulic oil is supplied to the contraction side hydraulic chamber <NUM>.

The oil path element L1c is provided with a cock <NUM>. This cock <NUM> can be manually or automatically switched between open and closed states. The cock <NUM> allows the flow of hydraulic oil from the upstream side (the oil path element L1b side) to the downstream side (the oil path element L1a side) in the open state. Furthermore, the cock <NUM> blocks the flow of hydraulic oil from the upstream side (the oil path element L1b side) to the downstream side (the oil path element L1a side) in the closed state. In the case of the present embodiment, the cock <NUM> is in the open state in normal times.

The first solenoid valve 604B switches between the first state that allows the flow of hydraulic oil from the upstream side to the downstream side and the second state that allows the flow of hydraulic oil from the downstream side to the upstream side in response to energization. In the case of the present embodiment, the first solenoid valve 604B is in the first state when it is in the energized state, and is in the second state when it is in the non-energized state.

The first solenoid valve 604B blocks the flow of hydraulic oil from the downstream side to the upstream side in the first state. On the other hand, the first solenoid valve 604B blocks the flow of hydraulic oil from the upstream side to the downstream side in the second state.

Specifically, the downstream end of the oil path element L3 is connected to a first port of the first solenoid valve 604B. An upstream end of the oil path element L3 is connected to an output port of the accumulator 602A. Furthermore, the oil path element L3 is provided with the pressure reducing valve 609a. The first solenoid valve 604B is connected to the accumulator 602A via the oil path element L3.

The upstream end of the oil path element L12 is connected to a second port of the first solenoid valve 604B. A downstream end of the oil path element L12 is connected to the second solenoid valve <NUM>. The first solenoid valve 604B is connected to the second solenoid valve <NUM> via the oil path element L12.

The downstream end of the oil path element L6 is connected to a third port of the first solenoid valve 604B. The upstream end of the oil path element L6 is connected to the branch point X. The first solenoid valve 604B is connected to the cylinder side hydraulic pressure source <NUM> via the oil path element L6 and the upstream oil path element L21.

This first solenoid valve 604B can supply hydraulic oil supplied from the oil path element L3 to the second solenoid valve <NUM> via the oil path element L12 in the first state.

On the other hand, the first solenoid valve 604B can supply the hydraulic oil supplied from the oil path element L12 to the cylinder side hydraulic pressure source <NUM> via the oil path element L6 and the upstream oil path element L21 in the second state.

The emergency switching mechanism <NUM> is provided to an oil path element L17. An upstream end of the oil path element L17 is connected to the upstream oil path element L21. That is, the oil path element L17 is connected to the cylinder side hydraulic pressure source <NUM> via the upstream oil path element L21. A downstream end of the oil path element L17 is connected to the oil path element L12.

The emergency switching mechanism <NUM> includes a relief valve 610c and a pressure reducing valve 609b in this order from the upstream side in the oil path element L17. In the oil path element L17, the oil path on the upstream side of the relief valve 610c is an oil path element L171. In the oil path element L17, the oil path between the relief valve 610c and the pressure reducing valve 609b is an oil path element L172. Furthermore, in the oil path element L17, the oil path on the downstream side of the relief valve 610c is an oil path element L173.

The relief valve 610c is normally in a closed state. This relief valve 610c becomes an open state when the hydraulic pressure in the oil path on the upstream side becomes equal to or higher than a predetermined pressure (valve opening pressure). In the open state, the relief valve 610c allows the flow of hydraulic oil from the upstream side to the downstream side.

The pressure reducing valve 609b reduces the pressure of the hydraulic oil flowing in from the upstream side and supplies it to the downstream side. The other configuration of the hydraulic mechanism 6B is almost the same as that in the first embodiment described above.

Next, the operation of the hydraulic mechanism 6B will be described with reference to <FIG>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism 6B in performing the disengaging operation of the boom connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism 6B in performing the engaging operation of the boom connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism 6B in performing the disengaging operation of the cylinder connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism 6B in performing the engaging operation of the cylinder connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism 6B in performing the disengaging operation of the cylinder connection mechanism <NUM> in an emergency.

First, the operation of the hydraulic mechanism 6B in performing the disengaging operation of the boom connection mechanism <NUM> will be described with reference to <FIG>. Since the configuration of each member in the hydraulic mechanism 6B is as described above, any overlapping description will be omitted.

For example, if the operator instructs the disengaging operation of the boom connection mechanism <NUM> in the state in which the distal end boom element <NUM> and the intermediate boom element <NUM> are connected (see <FIG>), the first solenoid valve 604B and the second solenoid valve <NUM> become the energized state.

As a result, the first solenoid valve 604B and the second solenoid valve <NUM> become the first state. Then, the hydraulic oil discharged from the accumulator 602A is supplied to the hydraulic chamber <NUM> of the boom connection mechanism <NUM> through the oil path illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a feed oil path in the normal oil path.

Specifically, the hydraulic oil flows through the accumulator 602A, the oil path element L3, the first solenoid valve 604B, the oil path element L12, the second solenoid valve <NUM>, the oil path element L14, and the hydraulic chamber <NUM> of the boom connection mechanism <NUM> in this order.

Next, the operation of the hydraulic mechanism 6B in performing the engaging operation of the boom connection mechanism <NUM> will be described with reference to <FIG>.

For example, if the operator instructs the engaging operation of the boom connection mechanism <NUM> in the state in which the distal end boom element <NUM> and the intermediate boom element <NUM> are not connected (see <FIG>), the second solenoid valve <NUM> becomes the energized state, whereas the first solenoid valve 604B becomes the non-energized state.

As a result, the second solenoid valve <NUM> becomes the first state, whereas the first solenoid valve 604B becomes the second state. Then, the hydraulic oil in the hydraulic chamber <NUM> of the boom connection mechanism <NUM> returns to the cylinder side hydraulic pressure source <NUM> through the oil path illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a return oil path in the normal oil path.

Specifically, the hydraulic oil flows through the hydraulic chamber <NUM> of the boom connection mechanism <NUM>, the oil path element L14, the second solenoid valve <NUM>, the oil path element L12, the first solenoid valve 604B, the oil path element L6, the upstream oil path element L21, and the cylinder side hydraulic pressure source <NUM> in this order.

As a result, the boom connection mechanism <NUM> transitions from the contraction state to the extension state, and the boom connection pins 51a are inserted across the boom pin receiving portions 141b of the distal end boom element <NUM> and the first boom pin receiving portions 142b (or the second boom pin receiving portions 142c) of the intermediate boom element <NUM>. In this case, as an example, the boom connection pins 51a transition from the state illustrated in <FIG> to the state illustrated in <FIG>.

Next, the operation of the hydraulic mechanism 6B in performing the disengaging operation of the cylinder connection mechanism <NUM> will be described with reference to <FIG>.

For example, if the operator instructs the disengaging operation of the cylinder connection mechanism <NUM> in the state of connection between the distal end boom element <NUM> and the cylinder member <NUM> as illustrated in <FIG>, the first solenoid valve 604B becomes the energized state, whereas the second solenoid valve <NUM> becomes the non-energized state.

As a result, the first solenoid valve 604B becomes the first state, whereas the second solenoid valve <NUM> becomes the second state. Then, the hydraulic oil discharged from the accumulator 602A is supplied to the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> through the oil path (also referred to as the first oil path) illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a feed oil path in the normal oil path.

Specifically, the hydraulic oil flows through the accumulator 602A, the oil path element L3, the first solenoid valve 604B, the oil path element L12, the second solenoid valve <NUM>, the oil path element L13, and the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> in this order.

Next, the operation of the hydraulic mechanism 6B in performing the engaging operation of the cylinder connection mechanism <NUM> will be described with reference to <FIG>.

For example, if the operator instructs the engaging operation of the cylinder connection mechanism <NUM> in the state of non-connection between the distal end boom element <NUM> and the cylinder member <NUM> as illustrated in <FIG>, the first solenoid valve 604B and the second solenoid valve <NUM> become the non-energized state.

As a result, the first solenoid valve 604B and the second solenoid valve <NUM> become the second state. Then, the hydraulic oil in the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> returns to the cylinder side hydraulic pressure source <NUM> through the oil path illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a return oil path in the normal oil path.

Specifically, the hydraulic oil flows through the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM>, the oil path element L13, the second solenoid valve <NUM>, the oil path element L12, the first solenoid valve 604B, the oil path element L6, the upstream oil path element L21, and the cylinder side hydraulic pressure source <NUM> in this order.

Next, the operation of the hydraulic mechanism 6B in performing the disengaging operation of the cylinder connection mechanism <NUM> in an emergency will be described with reference to <FIG>. In the present embodiment, the term "emergency" means a situation in which the first solenoid valve 604B and the second solenoid valve <NUM> cannot be energized and the switching of these valves cannot be performed.

For example, the operator closes the cock <NUM> (see <FIG>) if the first solenoid valve 604B and the second solenoid valve <NUM> cannot be energized in the state of connection between the distal end boom element <NUM> and the cylinder member <NUM> as illustrated in <FIG>. Then, the pilot pressure from the oil path element L1b acting on the counterbalance valve 601a decreases, and the counterbalance valve 601a blocks the passage of hydraulic oil discharged from the contraction side hydraulic chamber <NUM> of the telescopic cylinder <NUM>. Then, the operator instructs the disengaging operation of the cylinder connection mechanism <NUM> in an emergency through a predetermined operation (a switch operation, for example).

With the telescopic cylinder <NUM> transitioning in the contraction direction in response to the above-described instruction, the hydraulic pressure in the contraction side hydraulic chamber <NUM> increases, whereby hydraulic oil is supplied from the cylinder side hydraulic pressure source <NUM> (also referred to as a hydraulic pressure source) to the emergency switching mechanism <NUM>. Since the hydraulic pressure of such hydraulic oil exceeds the valve opening pressure for the relief valve 610c, the hydraulic oil passes through the relief valve 610c. The hydraulic oil that has passed through the relief valve 610c is depressurized by the pressure reducing valve 609b and flows into the oil path element L12.

As a result, the hydraulic oil discharged from the cylinder side hydraulic pressure source <NUM> is supplied to the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> through the oil path (also referred to as the second oil path) illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a feed oil path in the emergency oil path.

Specifically, the hydraulic oil flows through the cylinder side hydraulic pressure source <NUM>, the upstream oil path element L21, the oil path element L171, the relief valve 610c, the oil path element L172, the pressure reducing valve 609b, the oil path element L173, the oil path element L12, the second solenoid valve <NUM>, the oil path element L13, and the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> in this order.

As a result, the cylinder connection mechanism <NUM> transitions from the extension state to the contraction state, and the pair of cylinder connection pins <NUM> are disengaged from the cylinder pin receiving portions 141a of the distal end boom element <NUM>. In this case, as an example, the pair of cylinder connection pins <NUM> transition from the state illustrated in <FIG> to the state illustrated in <FIG>. Other configurations and actions/effects are the same as in the above-described first embodiment.

A third embodiment (non-claimed) will be described with reference to <FIG>. In the case of the present embodiment, the configuration of a hydraulic mechanism 6C is different from that in the above-described first embodiment. The configurations of the other parts are the same as those in the first embodiment. Hereinafter, the hydraulic mechanism 6C will be described.

The hydraulic mechanism 6C includes the cylinder side hydraulic pressure source <NUM>, the accumulator 602A, the first solenoid valve 604B, the second solenoid valve <NUM>, and an emergency switching valve <NUM>.

The cylinder side hydraulic pressure source <NUM>, the accumulator 602A, and the second solenoid valve <NUM> are the same as those in the first embodiment described above. The first solenoid valve 604B is the same as that in the second embodiment described above.

The emergency switching valve <NUM> is a second valve and is provided to the oil path element L12. In the oil path element L12, the oil path on the upstream side of the emergency switching valve <NUM> is an oil path element L121. Furthermore, in the oil path element L12, the oil path on the downstream side of the emergency switching valve <NUM> is an oil path element L122.

The emergency switching valve <NUM> can be manually switched between the first state and the second state by the operator. The means for switching the emergency switching valve <NUM> is not limited to the manual operation made by the operator. For example, the emergency switching valve <NUM> may be mechanically switched by a device driven in response to a predetermined operation (a switch operation, for example) made by the operator.

A downstream end of the oil path element L121 is connected to a first port of the emergency switching valve <NUM>. An upstream end of the oil path element L121 is connected to the second port of the first solenoid valve 604B. The emergency switching valve <NUM> is connected to the first solenoid valve 604B via the oil path element L121.

An upstream end of the oil path element L122 is connected to a second port of the emergency switching valve <NUM>. A downstream end of the oil path element L122 is connected to the second solenoid valve <NUM>. The emergency switching valve <NUM> is connected to the second solenoid valve <NUM> via the oil path element L122.

A downstream end of the oil path element L18 is connected to a third port of the emergency switching valve <NUM>. An upstream end of the oil path element L18 is connected to the oil path element L3. The oil path element L18 is a bypass oil path that bypasses the first solenoid valve 604B. The oil path element L18 is connected to the accumulator 602A via the oil path element L3.

The emergency switching valve <NUM> as described above permits the flow of hydraulic oil between the oil path element L121 and the oil path element L122 in the first state. In other words, the emergency switching valve <NUM> allows the flow of hydraulic oil between the first solenoid valve 604B and the second solenoid valve <NUM> in the first state. The emergency switching valve <NUM> blocks the flow of hydraulic oil between the oil path element L18 and the oil path element L122 in the first state.

On the other hand, the emergency switching valve <NUM> permits the flow of hydraulic oil between the oil path element L18 and the oil path element L122 in the second state. In other words, the emergency switching valve <NUM> allows the flow of hydraulic oil between the accumulator 602A and the second solenoid valve <NUM> in the second state. The emergency switching valve <NUM> blocks the flow of hydraulic oil between the oil path element L121 and the oil path element L122 in the second state.

Next, the operation of the hydraulic mechanism 6C will be described with reference to <FIG>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism 6C in performing the disengaging operation of the boom connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism 6C in performing the engaging operation of the boom connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism 6C in performing the disengaging operation of the cylinder connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism 6C in performing the engaging operation of the cylinder connection mechanism <NUM>. <FIG> is a diagram for explaining the operation of the hydraulic mechanism 6C in performing the disengaging operation of the cylinder connection mechanism <NUM> in an emergency.

First, the operation of the hydraulic mechanism 6C in performing the disengaging operation of the boom connection mechanism <NUM> will be described with reference to <FIG>. Since the configuration of each member in the hydraulic mechanism 6C is as described above, any overlapping description will be omitted.

As a result, the first solenoid valve 604B and the second solenoid valve <NUM> become the first state. In this state, the emergency switching valve <NUM> is in the above-mentioned first state. Then, the hydraulic oil discharged from the accumulator 602A is supplied to the hydraulic chamber <NUM> of the boom connection mechanism <NUM> through the oil path illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a feed oil path in the normal oil path.

Specifically, the hydraulic oil flows through the accumulator 602A, the oil path element L3, the first solenoid valve 604B, the oil path element L121, the emergency switching valve <NUM>, the oil path element L122, the second solenoid valve <NUM>, the oil path element L14, and the hydraulic chamber <NUM> of the boom connection mechanism <NUM> in this order.

As a result, the boom connection mechanism <NUM> transitions from the extension state to the contraction state, and the boom connection pins 51a are disengaged from the first boom pin receiving portions 142b (or the second boom pin receiving portions 142c) of the intermediate boom element <NUM>. In this case, as an example, the boom connection pins 51a transition from the state illustrated in <FIG> to the state illustrated in <FIG>.

Next, the operation of the hydraulic mechanism 6C in performing the engaging operation of the boom connection mechanism <NUM> will be described with reference to <FIG>.

Specifically, the hydraulic oil flows through the hydraulic chamber <NUM> of the boom connection mechanism <NUM>, the oil path element L14, the second solenoid valve <NUM>, the oil path element L122, the emergency switching valve <NUM>, the oil path element L121, the first solenoid valve 604B, the oil path element L6, the upstream oil path element L21, and the cylinder side hydraulic pressure source <NUM> in this order.

As a result, the boom connection mechanism <NUM> transitions from the contraction state to the extension state, and the boom connection pins 51a are inserted across the boom pin receiving portions 141b of the distal end boom element <NUM> and the first boom pin receiving portions 142b or the second boom pin receiving portions 142c of the intermediate boom element <NUM>. In this case, as an example, the boom connection pins 51a transition from the state illustrated in <FIG> to the state illustrated in <FIG>.

Next, the operation of the hydraulic mechanism 6C in performing the disengaging operation of the cylinder connection mechanism <NUM> will be described with reference to <FIG>.

Specifically, the hydraulic oil flows through the accumulator 602A, the oil path element L3, the first solenoid valve 604B, the oil path element L121, the emergency switching valve <NUM>, the oil path element L122, the second solenoid valve <NUM>, the oil path element L13, and the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> in this order.

Next, the operation of the hydraulic mechanism 6C in performing the engaging operation of the cylinder connection mechanism <NUM> will be described with reference to <FIG>.

Specifically, the hydraulic oil flows through the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM>, the oil path element L13, the second solenoid valve <NUM>, the oil path element L122, the emergency switching valve <NUM>, the oil path element L121, the first solenoid valve 604B, the oil path element L6, the upstream oil path element L21, and the cylinder side hydraulic pressure source <NUM> in this order.

Next, the operation of the hydraulic mechanism 6C in performing the disengaging operation of the cylinder connection mechanism <NUM> in an emergency will be described with reference to <FIG>. In the present embodiment, the term "emergency" means a situation in which the first solenoid valve 604B and the second solenoid valve <NUM> cannot be energized and the switching of these valves cannot be performed.

For example, the operator switches the emergency switching valve <NUM> to the second state if the first solenoid valve 604B and the second solenoid valve <NUM> cannot be energized in the state of connection between the distal end boom element <NUM> and the cylinder member <NUM> as illustrated in <FIG>. In this operation, the operator makes the telescopic cylinder <NUM> contract to move the cylinder member <NUM> of the telescopic cylinder <NUM> to a position within the reach of the operator, for example. In this operation, the distal end boom element <NUM> moves together with the telescopic cylinder <NUM>.

Then, after switching the emergency switching valve <NUM> to the second state, the operator instructs the disengaging operation of the cylinder connection mechanism <NUM> in an emergency through a predetermined operation (a switch operation, for example). Then, in response to the above-described instruction, the telescopic cylinder <NUM> transitions in the contraction direction. As a result, the hydraulic oil discharged from the accumulator 602A is supplied to the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> through the oil path (also referred to as the second oil path) illustrated by the thick solid line in <FIG>. The oil path illustrated by the thick solid line in <FIG> constitutes a feed oil path in the emergency oil path.

Specifically, the hydraulic oil flows through the accumulator 602A, the oil path element L3, the oil path element L18, the emergency switching valve <NUM>, the oil path element L122, the second solenoid valve <NUM>, the oil path element L13, and the hydraulic chamber <NUM> of the cylinder connection mechanism <NUM> in this order.

As a result, the cylinder connection mechanism <NUM> transitions from the extension state to the contraction state, and the pair of cylinder connection pins <NUM> are disengaged from the cylinder pin receiving portions 141a of the distal end boom element <NUM>. In this case, as an example, the pair of cylinder connection pins <NUM> transition from the state illustrated in <FIG> to the state illustrated in <FIG>. Other configurations and actions/effects are the same as in the above-described.

The disclosures of the specification, drawings and abstract are contained in the Japanese application of <CIT>.

Claim 1:
A crane (<NUM>) comprising:
a telescopic boom (<NUM>) that is capable of being extended;
an extension device (<NUM>) for extending the telescopic boom (<NUM>);
a hydraulic pressure source (<NUM>, 602A) provided in the extension device (<NUM>);
a cylinder connection mechanism (<NUM>) connected to the hydraulic pressure source (<NUM>, 602A) and switching between states of connection and non-connection with the telescopic boom (<NUM>) based on supply and discharge of hydraulic oil;
a first oil path for connecting the hydraulic pressure source (<NUM>, 602A) and the cylinder connection mechanism (<NUM>);
a first valve (<NUM>, 604B) that is provided on the first oil path and switches a supply and discharge state of the hydraulic oil with respect to the cylinder connection mechanism (<NUM>); and
a second oil path (L7, L17, L18) that bypasses the first valve (<NUM>, 604B) and connects the hydraulic pressure source (<NUM>, 602A) and the cylinder connection mechanism (<NUM>),
characterized in that:
the crane (<NUM>) further comprises a second valve (603A, <NUM>) that is capable of switching between a state in which the hydraulic pressure source (<NUM>, 602A) and the cylinder connection mechanism (<NUM>) are communicated through the first oil path and a state in which the hydraulic pressure source (<NUM>, 602A) and the cylinder connection mechanism (<NUM>) are communicated via the second oil path (L7, L17, L18);
a third valve (603B) that is capable of switching between a state in which a pilot pressure is supplied to the second valve (603A, <NUM>) and a state in which the pilot pressure is not supplied to the second valve (603A, <NUM>) in response to the energization,
wherein
when the third valve (603B) switches to the state in which the pilot pressure is not supplied, the second valve (603A, <NUM>) becomes a state in which the hydraulic pressure source (<NUM>, 602A) and the cylinder connection mechanism (<NUM>) are communicated through the second oil path (L7, L17, L18).