LUBRICATION SYSTEM


  1. CONSTRUCTION


    1. The variable discharge oil pump assembly is made up of a trochoid gear and a relief valve that distributes the oil into 3 oil passages according to the oil pump rotation speed.

    2. The relief valve reduces parasitic losses of engine power by providing appropriate oil pressure for each engine speed range.

      A00XR5TC02
      *1 Trochoid Gear *2 Relief Valve

  2. OPERATION


    1. Low Engine Speed Range


      1. At the low engine speed range, the oil pump assembly rotation speed and the discharge pressure are both low, so relief ports A and B are closed, and the oil in oil passages A and B is sent to the engine. As a result, the increase in discharge pressure is proportionate to the increase in rotation speed of the oil pump assembly.

        A00XRJ1E01

    2. Middle Engine Speed Range


      1. At the middle engine speed range, the discharge pressure in the oil pump assembly increases enough to overcome the pressure of the relief valve spring, and the relief valve is raised.

      2. The relief valve opens relief port A, and the oil in oil passage A is returned to the inlet side of the oil pump assembly. As a result, the volume of oil sent to the engine is controlled, and the increase in discharge pressure becomes more moderate than the increase in oil pump assembly rotation speed.

        A00XREHE02

    3. High Engine Speed Range (While Engine Speed is Increasing)


      1. At the high engine speed range, the oil pump assembly rotation speed increases more, resulting in higher discharge pressure, and so the relief valve is raised further.

      2. The relief valve closes relief port A and, at the same time, the flow of oil through oil passages A and B is allowed to merge again. This results in an increase in the volume of oil sent to the engine, increasing discharge pressure.

        A00XRBME02

    4. High Engine Speed Range (While Pressure is being Regulated)


      1. When the pressure is being regulated at the high engine speed range, the relief valve starts to open port B, and starts to return the flow of oil in oil passage C to the inlet side of the oil pump assembly. As a result, the increase in discharge pressure from the oil pump assembly again becomes more moderate than the increase in rotation speed.

        A00XRGCE01

    5. From High Engine Speed Range to Middle Engine Speed Range


      1. Due to the discharge pressure in the oil pump assembly when the rotation speed of the oil pump assembly falls from the high to the middle speed range, all of the oil in oil passage A is sent to the engine side via the relief valve. Because of this, the discharge pressure falls in accordance with the oil pump assembly rotation speed until relief port A is opened by the relief valve, and some of the oil in oil passage A is returned to the oil pump assembly inlet side. As a result, torque fluctuations in the oil pump assembly are suppressed, and engine speed decreases smoothly.

        A00XR7BE01