# US 2014/0190784 A1 · Parking lock device for transmission > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0190784 A1 - Document ID: US20140190784A1 - Status: Published application - Kind: A1 - Application number: 14/108,797 - Filed: 2013-12-17 - Published: 2014-07-10 - Earliest claimed: 2013-01-10 - Assignees: Honda Motor Co., Ltd. - Applicants: Honda Motor Co., Ltd. - Inventors: Hirotaka Yokota; Shunsuke Yoshida; Yutaka Ishikawa; Tetsuya Mochizuki - Web page: https://patentgrep.com/patent/US20140190784A1 ## CPC - B60T 1/005: {by locking of wheel or transmission rotation} - F16H 61/0025: {Supply of control fluid; Pumps therefor} - F16H 63/3416: {Parking lock mechanisms or brakes in the transmission} - F16H 63/3483: {with hydraulic actuating means} - F16H 63/3491: {Emergency release or engagement of parking locks or brakes} - B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES - F16H: GEARING ## Abstract In case of power supply loss, a parking lock is operated by moving a piston of a hydraulic actuator rightward by use of hydraulic pressure accumulated in an accumulator. If a hydraulic pressure generating source becomes unable to generate line pressure due to its failure after the power supply loss, it is desirable that the parking lock be releasable to tow a vehicle, for example. In that time, because the hydraulic pressure in the accumulator has got out via an orifice, the parking lock can be released by moving the piston in the hydraulic actuator leftward by use of a manual operation device without interruption by the hydraulic pressure accumulated in the accumulator. Because the hydraulic pressure in the accumulator is automatically released via the orifice, a complicated mechanism for enabling the manual operation device to work without interference from the hydraulic actuator becomes unnecessary. ## Claims ### Claim 1 A parking lock device for a transmission including: a parking gear; a parking pawl configured to be lockable when in mesh with the parking gear; a hydraulic pressure generating source configured to generate line pressure; a hydraulic actuator configured to operate the parking pawl into a lock position and an unlock position by use of the line pressure; and a manual release device for manually operating the parking pawl into the unlock position, wherein the hydraulic actuator includes an unlock oil chamber at one end, and a lock oil chamber at the other end, the line pressure is transmitted to the unlock oil chamber, the line pressure can be transmitted to the lock oil chamber via a first solenoid valve, hydraulic pressure from an accumulator configured to accumulate the line pressure can be transmitted to the lock oil chamber via a second solenoid valve, a check valve configured to allow oil to flow toward the accumulator only is provided upstream of the accumulator, and an orifice is connected to the accumulator in parallel. ### Claim 2 (depends on 1) The parking lock device for a transmission of claim 1, wherein the second solenoid valve is of a normally-open type. ### Claim 3 (depends on 1) The parking lock device for a transmission of claim 1, further comprising: a first oil passage connecting the hydraulic pressure generating source to the second solenoid valve; a second oil passage branching from the first oil passage, and connected to the first solenoid valve; a third oil passage branching from the first oil passage, and connected to the unlock oil chamber; and a switching valve placed in the second oil passage, wherein when a driver selects a range other than a drive range, the switching valve establishes communication through the second oil passage, when the driver selects the drive range, the switching valve shuts off the second oil passage. ### Claim 4 (depends on 3) The parking lock device for a transmission of claim 3, wherein the check valve is placed in the first oil passage, downstream of a branch part of the second oil passage in the first oil passage. ### Claim 5 (depends on 1) The parking lock device for a transmission of claim 1, wherein the hydraulic pressure generating source includes a first hydraulic pump driven by an engine, and a second hydraulic pump driven by a wheel, and of oil discharged by the first hydraulic pump and oil discharged by the second hydraulic pump, oil with a higher pressure is supplied via a three-way valve. ### Claim 6 (depends on 1) The parking lock device for a transmission of claim 1, wherein the lock oil chamber includes a first lock oil chamber to which the line pressure can be transmitted via the first solenoid valve, and a second lock oil chamber to which the hydraulic pressure from the accumulator can be transmitted via the second solenoid valve, the hydraulic actuator includes a piston slidably fitted in a cylinder, and the piston includes an O-ring configured to seal a gap between the first lock oil chamber and the second lock oil chamber. ### Claim 7 (depends on 2) The parking lock device for a transmission of claim 2, further comprising: a first oil passage connecting the hydraulic pressure generating source to the second solenoid valve; a second oil passage branching from the first oil passage, and connected to the first solenoid valve; a third oil passage branching from the first oil passage, and connected to the unlock oil chamber; and a switching valve placed in the second oil passage, wherein when a driver selects a range other than a drive range, the switching valve establishes communication through the second oil passage, when the driver selects the drive range, the switching valve shuts off the second oil passage.