Brake device

{
  "publication_number": "US9840243B2",
  "country": "US",
  "kind": "B2",
  "title": "Brake device",
  "abstract": "Provided is a brake device which improves energy efficiency. The brake device includes a stroke length adjusting unit configured to adjust rod stroke S R (stroke length of a piston in a master cylinder) relative to pedal stroke S P (quantity of operation of brake pedal by the driver).",
  "claims": [
    "1. A brake device comprising: a brake pedal; a master cylinder including a piston configured to stroke according to a quantity of brake pedal operation by a driver; and a stroke length adjusting unit configured to adjust a stroke length of the piston in the master cylinder, wherein the stroke length adjusting unit includes: a first range in which an amount of change in the stroke length of the piston in the master cylinder relative to an amount of change in brake pedal operation quantity has variable ratio characteristics during a time period between when the brake pedal operation by the driver is initiated and before the operation quantity reaches a predetermined value; and a second range in which the amount of change in the stroke length of the piston in the master cylinder relative to the amount of change in the brake pedal operation quantity has fixed ratio characteristics when the operation quantity is equal to or larger than the predetermined value, the ratio remaining fixed during the entire second range, and the stroke length adjusting unit includes a variable link mechanism configured to operate in the first range, and a fixed link mechanism configured to immediately take over the operation of the variable link mechanism in the second range.",
    "2. The brake device of claim 1, wherein the stroke length adjusting unit includes a link mechanism, the brake pedal is pivotally supported by a bracket; and the link mechanism includes: a first link with one end pivotally connected to the brake pedal; a second link with one end connected to a pushrod of the master cylinder, the second link including a first slide portion formed along an axial direction on the other end side, and a second slide portion formed along the axial direction in a portion between the first slide portion and the one end side; a first intermediate link with one end pivotally connected to the other end of the first link, the other end engaged with the first slide portion of the second link, and a portion between both the ends, which is pivotally supported by the bracket; and a second intermediate link with one end pivotally connected to the brake pedal, and the other end engaged with the second slide portion of the second link.",
    "3. The brake device of claim 2, wherein at the time of initiation of brake pedal operation, the other end of the first intermediate link is engaged with the first slide portion, and the other end of the second intermediate link is engaged with the second slide portion with allowance.",
    "4. The brake device of claim 2, wherein at least one of the first and second slide portions is a slotted hole formed along a longitudinal direction of the second link.",
    "5. The brake device of claim 4, wherein the first intermediate link includes a first engagement pin engaged with the slotted hole.",
    "6. The brake device of claim 5, further including a first shock-absorbing member disposed in at least one end of the slotted hole, and configured to come into contact with the first engagement pin.",
    "7. The brake device of claim 4, wherein the second intermediate link includes a second engagement pin engaged with the slotted hole.",
    "8. The brake device of claim 6, further including a second shock-absorbing member disposed in at least one end of the slotted hole, and configured to come into contact with the second engagement pin.",
    "9. The brake device of claim 2, wherein the first and second intermediate links contact each other with an elastic member intervening therebetween when the operation quantity is between a first value smaller than the predetermined value and a second value larger than the predetermined value.",
    "10. A brake device comprising: a brake pedal; a master cylinder including a piston configured to stroke according to a quantity of brake pedal operation by a driver; and a stroke length adjusting unit configured to adjust a stroke length of the piston in the master cylinder, wherein the stroke length adjusting unit is configured so that an increase gradient of a wheel-cylinder hydraulic pressure relative to pedal effort during a time period between when the brake pedal operation by the driver is initiated and before the pedal effort reaches a predetermined value is larger than an increase gradient of the wheel-cylinder hydraulic pressure relative to the pedal effort equal to or larger than the predetermined value, the stroke length adjusting unit includes a link mechanism, and the link mechanism includes: a first link with one end pivotally connected to the brake pedal; a second link with one end connected to a pushrod of the master cylinder, the second link including a first slide portion formed along an axial direction on the other end side, and a second slide portion formed along the axial direction in a portion between the first slide portion and the one end side; a first intermediate link with one end pivotally connected to the other end of the first link, the other end enaged with the first slide portion of the second link, and a portion between both end portions, which is pivotally supported by a bracket; and a second intermediate link with one end pivotally connected to the brake pedal, and the other end engaged with the second slide portion of the second link.",
    "11. The brake device of claim 10, wherein the wheel-cylinder hydraulic pressure is provided so that an amount of change in the wheel-cylinder hydraulic pressure relative to an amount of change in the pedal effort has variable ratio characteristics when the pedal effort is smaller than the predetermined value, and has fixed ratio characteristics when the pedal effort is equal to or larger than the predetermined value.",
    "12. The brake device of claim 10, wherein the stroke length adjusting unit includes a variable link mechanism configured to operate according to the brake pedal operation when the pedal effort is smaller than the predetermined value, and a fixed link mechanism configured to immediately take over the operation of the variable link mechanism when the pedal effort is equal to or larger than the predetermined value.",
    "13. The brake device of claim 10, wherein at the initiation of brake pedal operation, the other end of the first intermediate link is engaged with the first slide portion, and the other end of the second intermediate link is engaged with the second slide portion with allowance.",
    "14. The brake device of claim 13, wherein the first and second slide portions are slotted holes formed along a longitudinal direction of the second link.",
    "15. The brake device of claim 10, wherein the first and second intermediate links contact each other with an elastic member intervening therebetween when the operation quantity is between a first value smaller than the predetermined value and a second value larger than the predetermined value.",
    "16. A brake device comprising: a brake pedal; a master cylinder including a piston configured to stroke according to a quantity of brake pedal operation by a driver; and a stroke length adjusting unit including a link mechanism and configured to adjust a stroke length of a piston in a master cylinder, wherein the stroke length adjusting unit is configured so that an increase gradient of a wheel-cylinder hydraulic pressure relative to an operation quantity during a time period between when the brake pedal operation by the driver is initiated and before the operation quantity reaches a predetermined value is smaller than an increase gradient of the wheel-cylinder hydraulic pressure relative to the operation quantity equal to or larger than the predetermined value, the link mechanism includes: a first link with one end pivotally connected to the brake pedal; a second link with one end connected to a pushrod of the master cylinder, the second link including a first slotted hole formed along an axial direction on the other end side, and a second slotted hole formed along the axial direction in a portion between the first slotted hole and the one end side; a first intermediate link with one end pivotally connected to the other end of the first link, the other end engaged with the first slotted hole of the second link, and a portion between both the ends, which is pivotally supported by a bracket; and a second intermediate link with one end pivotally connected to the brake pedal, and the other end engaged with the second slotted hole of the second link, and at the initiation of brake pedal operation, the other end of the first intermediate link is engaged with the first slotted hole, and the other end of the second intermediate link is engaged with the second slotted hole with allowance.",
    "17. The brake device of claim 16, wherein the wheel-cylinder hydraulic pressure is provided so that an amount of change in the wheel-cylinder hydraulic pressure relative to an amount of change in the operation quantity has variable ratio characteristics when the operation quantity is smaller than a predetermined value, and has fixed ratio characteristics when the operation quantity is equal to or larger than the predetermined value."
  ],
  "description_excerpt": "The invention relates to a brake device installed in a vehicle.\n\nA well-known brake device is the one with a booster which generates an assisting force for reducing a brake pedal applying force applied by a driver. The brake device disclosed, for example, in a Patent Document 1 generates an assisting force by using a hydraulic booster which is supplied with brake fluid from a hydraulic power source (accumulator).\n\nPatent Document 1: Japanese Unexamined Patent Application Publication No. 2008-6893\n\nConventional technology has difficulty in enhancing energy efficiency. It is an object of the invention to provide a brake device capable of enhancing energy efficiency.\n\nTo achieve the object, the brake device of the present invention includes a stroke length adjusting unit configured to adjust the stroke length of a piston in a master cylinder, relative to the quantity of brake pedal operation by a driver.\n\nThe invention thus enhances energy efficiency.\n\nFIG. 1 is a perspective view of a brake pedal 2 and a stroke length adjusting unit 3 according to Embodiment 1 (with an elastic member 6 and the like omitted from the figure).\n\nFIG. 2 is a perspective view of the brake pedal 2 and the stroke length adjusting unit 3 according to Embodiment 1 (with the elastic member 6 and the like omitted from the figure).\n\nFIG. 3 is a perspective view of a second link 32 according to Embodiment 1.\n\nFIG. 4 is a perspective view of the brake pedal 2 and the stroke length adjusting unit 3 according to Embodiment 1 (with the elastic member 6 and the like illustrated).",
  "cpc": [
    "B60T 11/18",
    "B60T 7/06",
    "G05G 1/44",
    "G05G 7/04"
  ],
  "ipc": [
    "B60T 11/18",
    "B60T 7/06",
    "G05G 7/04"
  ],
  "assignees": [
    "Hitachi Automotive Systems Ltd"
  ],
  "inventors": [
    "Masayuki Saito"
  ],
  "filing_date": "2014-09-11",
  "publication_date": "2017-12-12",
  "grant_date": "2017-12-12",
  "priority_date": "2013-09-19",
  "application_number": "US-201414917646-A",
  "family_id": "52688774",
  "cited_by_count": 11,
  "citations": [
    "JPS5145729A",
    "JPS548242A",
    "US6918318B2",
    "JP2005329872A",
    "US7584683B2",
    "US20070277640A1",
    "CN101085614A",
    "US20080001473A1",
    "JP2008006893A",
    "DE102011004041A1"
  ]
}