# US 2014/0196627 A1 · Railcar damping device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0196627 A1 - Document ID: US20140196627A1 - Status: Published application - Kind: A1 - Application number: 14/127,896 - Filed: 2012-06-19 - Published: 2014-07-17 - Earliest claimed: 2011-12-20 - Assignees: Kayaba Industry Co., Ltd. - Inventors: Takayuki Ogawa; Jun Aoki; Masaru Uchida - Web page: https://patentgrep.com/patent/US20140196627A1 ## CPC - B61F 5/24: Means for damping or minimising the canting, skewing, pitching, or plunging movements of the underframes - B61F 5/245: {by active damping, i.e. with means to vary the damping characteristics in accordance with track or vehicle induced reactions, especially in high speed mode} - F15B 21/008: {Reduction of noise or vibration} - F15B 2211/3058: having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode - F15B 2211/31558: having a single output member - F15B 2211/6303: using input signals - F15B 2211/6651: Control of the prime mover, e.g. control of the output torque or rotational speed - F15B 2211/6653: Pressure control - F15B 2211/7053: Double-acting output members - F15B 2211/76: Control of force or torque of the output member - F16F 15/027: comprising control arrangements {(F16F15/0237 takes precedence)} - B61F: RAIL VEHICLE SUSPENSIONS, e.g. UNDERFRAMES, BOGIES OR ARRANGEMENTS OF WHEEL AXLES; RAIL VEHICLES FOR USE ON TRACKS OF DIFFERENT WIDTH; PREVENTING DERAILING OF RAIL VEHICLES; WHEEL GUARDS, OBSTRUCTION REMOVERS OR THE LIKE FOR RAIL VEHICLES (for vehicles in general B60; axles or wheels B60B; vehicle tyres B60C) - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION ## Abstract A railcar damping device includes: a tank storing a liquid; a first opening/closing valve provided in a first passage connecting a rod side chamber to a piston side chamber, which are defined by a piston, to be capable of opening and closing the first passage; a second opening/closing valve provided in a second passage connecting the piston side chamber to the tank to be capable of opening and closing the second passage; and a pump that is driven to rotate at a predetermined normal rotation speed in order to supply the liquid from the tank to the rod side chamber, wherein a rotation speed of the pump is reduced when a thrust command value is smaller than a normal lower limit value, which is a lower limit value of a thrust that can be generated by the actuator when the pump is rotated at the normal rotation speed. ## Claims ### Claim 1 A railcar damping device that suppresses vibration of a vehicle body by determining a thrust to be output by an actuator as a thrust command value and controlling the actuator, wherein the actuator comprises: a cylinder coupled to one of a truck and the vehicle body of a railcar; a piston inserted into the cylinder to be free to slide; a rod inserted into the cylinder and coupled to the piston and the other of the truck and the vehicle body; and a rod side chamber and a piston side chamber defined within the cylinder by the piston, wherein the railcar damping device comprises: a tank that is configured to store a liquid that is supplied to and discharged from the cylinder; a first opening/closing valve provided in a first passage connecting the rod side chamber to the piston side chamber to be capable of opening and closing the first passage; a second opening/closing valve provided in a second passage connecting the piston side chamber to the tank to be capable of opening and closing the second passage; and a pump that is configured to be driven to rotate at a predetermined normal rotation speed in order to supply the liquid from the tank to the rod side chamber, wherein a rotation speed of the pump is reduced when the thrust command value is smaller than a normal lower limit value, which is a lower limit value of a thrust that can be generated by the actuator when the pump is rotated at the normal rotation speed. ### Claim 2 (depends on 1) The railcar damping device as defined in claim 1, wherein the rotation speed of the pump is reduced when the thrust command value remains smaller than the normal lower limit value continuously for a predetermined time. ### Claim 3 (depends on 1) The railcar damping device as defined in claim 1, wherein a low thrust rotation speed that is lower than the normal rotation speed is set in advance so that the rotation speed of the pump can be switched in two stages, i.e. between the normal rotation speed and the low thrust rotation speed. ### Claim 4 (depends on 1) The railcar damping device as defined in claim 1, wherein the rotation speed of the pump is returned to the normal rotation speed when the thrust command value increases to or above the normal lower limit value after the rotation speed of the pump has been reduced. ### Claim 5 (depends on 1) The railcar damping device as defined in claim 1, wherein the rotation speed of the pump is returned to the normal rotation speed when the thrust command value increases to or above the normal lower limit value after the rotation speed of the pump has been reduced and remains at or above the normal lower limit value continuously for a predetermined time. ### Claim 6 (depends on 4) The railcar damping device as defined in claim 4, wherein, when the rotation speed of the pump is reduced or returned, the rotation speed is varied over time. ### Claim 7 (depends on 1) The railcar damping device as defined in claim 1, further comprising: an exhaust passage connecting the rod side chamber to the tank; and a variable relief valve that is provided midway in the exhaust passage and has a modifiable valve opening pressure, wherein the thrust of the actuator is controlled by adjusting the valve opening pressure of the variable relief valve. ### Claim 8 (depends on 1) The railcar damping device as defined in claim 1, further comprising: a suction passage that is configured to allow the liquid to flow only from the tank toward the piston side chamber; and a rectifying passage that is configured to allow the liquid to flow only from the piston side chamber toward the rod side chamber.