Telescopic boom extension device

{
  "publication_number": "US9688519B2",
  "country": "US",
  "kind": "B2",
  "title": "Telescopic boom extension device",
  "abstract": "A telescopic boom extension device includes a driving mechanism. The driving mechanism that drives B pins and a C pin includes a hydraulic supply part and a drive source generation part. The drive source generation part generates a predetermined hydraulic pressure at the hydraulic supply part based on a pneumatic pressure. The hydraulic supply part has an accumulator and AOHs and supplies a hydraulic pressure to a cylinder-boom coupling mechanism and an inter-boom fixing mechanism. The drive source generation part uses a pneumatic supply part to send compressed air to the hydraulic supply part.",
  "claims": [
    "1. A telescopic boom extension device applied to a telescopic boom in which a base boom, an intermediate boom inserted into the base boom, and a top boom inserted into the intermediate boom constitute a telescopic structure, a boom fixing member is provided to couple an adjacent pair of the booms when the adjacent booms are in a fully-extended state or a fully-contracted state, and when a single built-in extension cylinder extends or retracts, the extension cylinder is coupled selectively to the top boom and the intermediate boom in sequence via a cylinder fixing member to extend the top boom and the intermediate boom in sequence, the telescopic boom extension device comprising: a hydraulic supply part that includes: an accumulator configured to supply operating oil under a predetermined pressure to a first hydraulic actuator and a second hydraulic actuator; and an air over hydraulic booster (AOH) configured to accumulate pressure in the accumulator, the first and the second hydraulic actuators being configured to drive the boom fixing member and the cylinder fixing member, respectively, the hydraulic supply part being placed in the vicinity of the extension cylinder; and a drive source generation part that includes a pneumatic supply part configured to supply a pneumatic pressure and that is configured to generate operating oil under a predetermined pressure at the hydraulic supply part based on the pneumatic pressure.",
    "2. The telescopic boom extension device according to claim 1, further comprising: a pressure sensor configured to detect internal pressure in the accumulator; and a control unit configured to operate the drive source generation part to activate the AOH, when determining that the internal pressure is equal to or lower than a specific value based on an output signal from the pressure sensor.",
    "3. The telescopic boom extension device according to claim 1, wherein the AOH includes an air cylinder including an air piston and an air tube, wherein the air piston is slidable relative to the air tube without being biased in any direction.",
    "4. A telescopic boom extension device applied to a telescopic boom in which a base boom, an intermediate boom inserted into the base boom, and a top boom inserted into the intermediate boom constitute a telescopic structure, a boom fixing member is provided to couple an adjacent pair of the booms when the adjacent booms are in a fully-extended state or a fully-retracted state, and when a single built-in extension cylinder extends or retracts, the extension cylinder is coupled selectively to the top boom and the intermediate boom in sequence via a cylinder fixing member to extend the top boom and the intermediate boom in sequence, the telescopic boom extension device comprising: a hydraulic supply part that includes: an air over hydraulic booster (AOH) configured to supply operating oil under a predetermined pressure to a first hydraulic actuator and a second hydraulic actuator; and an air tank unit configured to supply compressed air to the AOH, the first and the second hydraulic actuators being configured to drive the boom fixing member and the cylinder fixing member, respectively, the hydraulic supply part being placed in the vicinity of the extension cylinder; and a drive source generation part that includes a pneumatic supply part configured to supply a pneumatic pressure and that is configured to fill the air tank unit with compressed air based on the pneumatic pressure.",
    "5. The telescopic boom extension device according to claim 4, further comprising: a pressure sensor configured to detect a filling pressure in the air tank unit; and a control unit configured to, operate the drive source generation part to fill the air tank unit with compressed air, when determining that the filling pressure is equal to or lower than a specific value based on an output signal from the pressure sensor.",
    "6. The telescopic boom extension device according to claim 4, wherein the AOH includes an air cylinder including an air piston and an air tube, wherein the air piston is slidable relative to the air tube without being biased in any direction."
  ],
  "description_excerpt": "Technical Field The present invention relates to a telescopic boom extension device for extending and retracting a telescopic boom mounted on a mobile crane. Related Art Mobile cranes such as a rough-terrain crane, for example, generally include a multistage telescopic boom. The telescopic boom is extended and retracted using a hydraulic cylinder in general. In particular, devices for extending and retracting a telescopic boom using a single double-acting hydraulic cylinder have been proposed (hereinafter, referred to as “extension device”) (for example, refer to JP 7-267584 A, JP No. 4612144, and JP No. 4709415). The extension device is structured as described below. The multistage telescopic boom includes bottom-stage and top-stage booms so called the base boom and the top boom, respectively, and one or more booms placed between the foregoing booms, which are so called intermediate booms. When the telescopic boom includes a plurality of intermediate booms, the intermediate boom adjacent to the top boom is referred to as a first intermediate boom, and the other intermediate boom adjacent to the first mediate boom is referred to as a second intermediate boom while the other intermediate boom adjacent to the second intermediate boom is referred to as a third intermediate boom, and so forth. Each of the booms extends (slides forth) and retracts (slides back) relative to the adjacent boom and is kept by a boom fixing pin (hereinafter, referred to as “B pin”) in the fully-retracted state and the fully-extended state.",
  "cpc": [
    "B66C 23/705",
    "B66C 23/22"
  ],
  "ipc": [
    "B66C 23/06",
    "B66C 23/22",
    "B66C 23/70"
  ],
  "assignees": [
    "TADANO LTD"
  ],
  "inventors": [
    "KAWABUCHI NAOTO",
    "KAWANO TAKASHI"
  ],
  "filing_date": "2016-02-04",
  "publication_date": "2017-06-27",
  "grant_date": "2017-06-27",
  "priority_date": "2015-02-24",
  "application_number": "US-201615015647-A",
  "family_id": "55411230",
  "citations": [
    "JP2013539525A",
    "JP4612144B2",
    "JP4709415B2",
    "JPH07267584A",
    "US2013220749A1",
    "US2833422A",
    "US3624979A",
    "US4459786A",
    "US4478014A",
    "US4663900A",
    "US4676340A",
    "US4688690A",
    "US5628416A",
    "US7497140B2"
  ]
}