# US 10,119,557 B2 · Hydraulic driving device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,119,557 B2 - Document ID: US10119557B2 - Status: Granted - Kind: B2 - Application number: 14/385,628 - Filed: 2014-05-29 - Published: 2016-08-18 - Granted: 2018-11-06 - Earliest claimed: 2014-05-29 - Assignees: Komatsu Ltd. - Applicants: Komatsu Ltd. - Inventors: Takuya Miyata; Shinobu Naitou - Web page: https://patentgrep.com/patent/US10119557B2 ## CPC - F15B 13/042: operated by fluid pressure {(F15B13/0401, F15B13/0416 take precedence)} - F03C 1/26: adapted for special use or combined with apparatus driven thereby - F15B 11/08: with only one servomotor - F15B 13/0401: {Valve members; Fluid interconnections therefor} - F16H 61/4104: Flushing, e.g. by using flushing valves or by connection to exhaust - F16H 61/44: with more than one pump or motor in operation - B60K 8/00: Arrangement or mounting of propulsion units not provided for in one of main groups B60K1/00 - B60K7/00 - B66F 9/07572: {Propulsion arrangements} - E02F 9/2225: {using pressure-compensating valves} - E02F 9/2289: {Closed circuit} - F15B 2013/008: {Throttling member profiles} - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - F03C: POSITIVE-DISPLACEMENT ENGINES DRIVEN BY LIQUIDS (positive- displacement engines for liquids and elastic fluids F01; positive- displacement machines for liquids F04; fluid-pressure actuators F15B; fluid gearing F16H) - F16H: GEARING - B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES - B66F: HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD ({invalid lifting devices A61G7/10; } mounting artificial islands on piles or like supports E02B17/00; scaffolding combined with lifting devices E04G1/22; lifting devices for sliding forms E04G11/24; lifting of buildings E04G23/06; shores or struts E04G25/00; lifts or other hoisting devices on ladders E06C7/12; props for mining E21D15/00) - E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00) ## Abstract A hydraulic driving device includes: a hydraulic motor configured to operate by flushing oil from a hydraulic pump through a high pressure oil passage and a low pressure oil passage; a low pressure selective valve configured to operate in accordance with differential pressure between the high pressure oil passage and the low pressure oil passage, and to discharge the oil in the low pressure oil passage inside a motor case; a tank oil passage configured to connect the inside of the motor case with an oil tank; and a choke throttle provided to the low pressure selective valve or to an oil passage lower than the low pressure selective valve. ## Claims ### Claim 1 A hydraulic driving device comprising: a hydraulic motor configured to operate by flushing oil from a hydraulic pump through a high pressure oil passage and a low pressure oil passage; a low pressure selective valve configured to operate in accordance with differential pressure between the high pressure oil passage and the low pressure oil passage, and to discharge the oil in the low pressure oil passage inside a motor case; wherein the low pressure selective tank includes a spool, a tank oil passage configured to connect the inside of the motor case with an oil tank; and a choke throttle being provided within the low pressure selective valve and disposed substantially coaxially and symmetrically to a central horizontal axis of the spool, wherein the spool includes a first annular recess portion, a second annular recess portion, a first center hole, and a second center hole, the first center hole and the second center hole being extended along a central axis of the spool to respective positions of the first annular recess portion and the second annular recess portion and with a uniform diameter, the first center hole and the second center hole being in fluid communication with the first annular recess portion and the second annular recess portion, respectively, the first annular recess portion and the second annular recess portion being in fluid communication with the high pressure oil passage and the low pressure oil passage, respectively. ### Claim 2 (depends on 1) The hydraulic driving device according to claim 1, wherein the high pressure oil passage supplies oil discharged from the hydraulic pump to the hydraulic motor, and the low pressure oil passage is connected so as to flow back the oil discharged from the hydraulic motor to the hydraulic pump, and is included in a closed circuit which circulatively supplies the oil between the hydraulic motor and the hydraulic pump together with the high pressure oil passage. ### Claim 3 A hydraulic driving device for a wheel loader, the hydraulic driving device comprising: a hydraulic motor configured to operate by flushing oil from a hydraulic pump through a high pressure oil passage and a low pressure oil passage; a low pressure selective valve configured to operate in accordance with differential pressure between the high pressure oil passage and the low pressure oil passage, and to discharge the oil in the low pressure oil passage inside a motor case; wherein the low pressure selective valve includes a spool, a tank oil passage configured to connect the inside of the motor case with an oil tank; and a choke throttle being provided within the low pressure selective valve and disposed substantially symmetrically to a central axis of the spool, 1, wherein the spool includes a first annular recess portion, a second annular recess portion, a first center hole, and a second center hole, the first center hole and the second center hole being extended along a central axis of the spool to respective positions of the first annular recess portion and the second annular recess portion and with a uniform diameter, the first center hole and the second center hole being in fluid communication with the first annular recess portion and the second annular recess portion, respectively, the first annular recess portion and the second annular recess portion being in fluid communication with the high pressure oil passage and the low pressure oil passage, respectively; wherein the choke throttle is an annular gap flow that satisfies the following formula. 0 <(δ^2)·d/L<2.5 where δ=(D−d)/2, “D” represents a choke external diameter, “d” represents a choke internal diameter, and “L” represents a choke length. ### Claim 4 (depends on 1) The hydraulic driving device according to claim 1, wherein the choke throttle is a cylindrical gap flow that satisfies the following formula. 0 <(d^4)/L<1.6 where “d” represents a choke internal diameter, while “L” represents a choke length.