An object of the present invention is to provide a pump device that is capable of improving a discharge performance. A first orifice 301 that is provided on a discharge oil passage (a pipe 12 ) of a pump 2 and a second orifice 302 that, when a flow amount Q becomes greater than a predetermined flow amount Q 1 , allows pass of brake fluid are provided.
1. A pump device including a pulsation reduction unit, which reduces pulsation of brake fluid discharged from a pump, the pulsation reduction unit comprising:
a dividing plate, movably located in a space provided on a discharge oil passage of the pump, dividing the space into an upstream side chamber and a downstream side chamber;
a spring element configured to engage a wall portion of the space and perform a sealing function that stops leakage of the brake fluid between the upstream side chamber and the downstream side chamber through a gap located at an outer peripheral side of the dividing plate;
a valve body provided in the upstream side chamber, defining a first chamber to which the discharge oil passage opens and a second chamber to which the discharge oil passage does not open in the upstream side chamber by closing when a flow amount of the brake fluid discharged from the pump is equal to or less than a predetermined flow amount, the valve body opening when the flow amount of the discharged brake fluid is greater than the predetermined flow amount;
a first orifice, which is formed by penetrating the dividing plate, that opens to the first chamber; and
a second orifice, which is formed by penetrating the dividing plate, that opens to the second chamber; wherein:
when the flow amount of the discharged brake fluid is greater than the predetermined flow amount, the dividing plate moves forward and backward in response to a hydraulic pressure variation due to pulsation of the discharged brake fluid with the valve body open.
2. The pump device as claimed in claim 1 , wherein:
the pump has a delivery valve that allows only a flow of the brake fluid in a discharge direction of the pump, and
the pulsation reduction unit is provided at a downstream side of the delivery valve.
3. The pump device as claimed in claim 1 , wherein:
the pulsation reduction unit has a third orifice, which is provided parallel to the second orifice and through which, when the flow amount becomes a second predetermined flow amount that is greater than the predetermined flow amount, the brake fluid passes.
4. A pulsation reduction unit for a pump device, the pulsation reduction unit reducing pulsation of brake fluid discharged from a pump and comprising:
a dividing plate, movably located in a space provided on a discharge oil passage of the pump, dividing the space into an upstream side chamber and a downstream side chamber;
a spring element configured to engage a wall portion of the space and perform a sealing function that stops leakage of the brake fluid between the upstream side chamber and the downstream side chamber through a gap located at an outer peripheral side of the dividing plate;
a valve body provided in the upstream side chamber, defining a first chamber to which the discharge oil passage opens and a second chamber to which the discharge oil passage does not open in the upstream side chamber by closing when a flow amount of the brake fluid discharged from the pump is equal to or less than a predetermined flow amount, the valve body opening when the flow amount of the discharged brake fluid is greater than the predetermined flow amount;
a first orifice, which is formed by penetrating the dividing plate, that opens to the first chamber; and
a second orifice, which is formed by penetrating the dividing plate, and which opens to the second chamber.
5. The pulsation reduction unit for the pump device as claimed in claim 4 , wherein:
the pump has a delivery valve that allows only a flow of the brake fluid in a discharge direction of the pump, and
the pulsation reduction unit is provided at a downstream side of the delivery valve.
6. A pump device including a pulsation reduction unit, which reduces pulsation of brake fluid discharged from a pump, the pulsation reduction unit comprising:
a dividing plate, movably located in a space provided on a discharge oil passage of the pump, dividing the space into an upstream side chamber and a downstream side chamber;
a spring element configured to engage a wall portion of the space and perform a sealing function that stops leakage of the brake fluid between the upstream side chamber and the downstream side chamber through a gap located at an outer peripheral side of the dividing plate;
a valve body provided in the upstream side chamber, defining a first chamber to which the discharge oil passage opens and a second chamber to which the discharge oil passage does not open in the upstream side chamber by closing when a flow amount of the brake fluid discharged from the pump is equal to or less than a predetermined flow amount, the valve body opening when the flow amount of the discharged brake fluid is greater than the predetermined flow amount;
a first fixed orifice, which is formed by penetrating the dividing plate, that opens to the first chamber; and
a second fixed orifice, which is formed by penetrating the dividing plate, that opens to the second chamber.
7. The pump device as claimed in claim 6 , wherein:
the first fixed orifice and the second fixed orifice are arranged parallel to each other with reference to a flow of the brake fluid.
8. The pump device as claimed in claim 7 , wherein:
the pump has a delivery valve that allows only a flow of the brake fluid in a discharge direction of the pump, and
the space is provided at a downstream side of the delivery valve.
9. The pump device as claimed in claim 8 , wherein:
the dividing plate has a third fixed orifice, which is parallel to the second fixed orifice and through which, when the discharge flow amount becomes a second predetermined flow amount that is greater than the predetermined flow amount, the brake fluid passes.