Impeller and fluid pump having the same

A fluid pump comprising:

• a case member that has an inlet port and a pump passage;
• and
• an impeller that is rotatable in the case member, the impeller having a plurality of vane grooves along the pump passage extending along a rotative direction of the impeller, each vane groove defined by a back surface on a backside with respect to the rotative direction,
• wherein at least a radially inner side of the back surface is inclined to a radially outer side backwardly with respect to the rotative direction,
• the back surface has a radially inner end and a radially outer end, which are connected via a first line segment,
• the first line segment is inclined relative to a straight line, which extends radially outwardly from the radially inner end along a radius of the impeller, backwardly with respect to the rotative direction,
• the impeller has a thickness-center with respect to a thickness direction of the impeller,
• at least an inlet side of the back surface on a side of the inlet port is inclined from the thickness-center toward the inlet port with respect to the thickness direction forwardly with respect to the rotative direction,
• the case member has a communication wall that defines a communication passage communicating the inlet port with the pump passage,
• the communication wall has an inlet-side end and a passage-side end that are connected via an inclining straight line, which is gradually elevated from the inlet port toward the pump passage,
• the inclining straight line and a second line segment, which extends from the thickness-center of the back surface to the inclining straight line through the inlet-side end of the back surface, define an angle ε forwardly with respect to the rotative direction, and
• the angle ε satisfies the following relationship:
• 90°≦ε≦130°.

A fluid pump comprising:

• a case member that defines a pump passage therein;
• and
• an impeller, which is rotatable in case member to pressurize fluid in the pump passage along a rotative direction of the impeller,
• wherein the impeller includes a plurality of partition walls along the rotative direction, adjacent two of the plurality of partition walls defining a vane groove therebetween,
• each partition wall has a back surface on a backside with respect to the rotative direction,
• at least a radially inner side of the back surface is radially outwardly inclined backwardly with respect to the rotative direction,
• the back surface has a radially inner end and a radially outer end, which are connected via a first line segment,
• the first line segment and a first straight line, which extends radially outwardly from the radially inner end along a radius of the impeller, define a backward inclining angle α therebetween,
• the impeller has a thickness-center and thickness-ends with respect to a thickness direction of the impeller,
• the back surface is inclined from the thickness-center toward both the thickness-ends forwardly with respect to the rotative direction,
• the thickness-center and each of the thickness-ends are connected via a second line segment,
• the second line segment and a second straight line, which extends from the thickness-center along the circumferential direction forwardly with respect of the rotative direction, define a forward inclining angle β therebetween, and
• the backward inclining angle α and the forward inclining angle β satisfy the following relationships:
• 15°≦α≦30°;
• β≦60°;
• and 1≦β/α≦4.

An impeller, which is rotatable in a fluid pump having a pump passage extending along a rotative direction of the impeller, the impeller comprising:

• a plurality of partition walls that is arranged along the rotative direction, adjacent two of the plurality of partition walls defining a vane groove therebetween,
• wherein each partition wall has a back surface on a backside with respect to the rotative direction,
• at least a radially inner side of the back surface is radially outwardly inclined backwardly with respect to the rotative direction,
• the back surface has a radially inner end and a radially outer end, which are connected via a first line segment defining a backward inclining angle α being an acute angle with respect to a radius of the impeller,
• the back surface is inclined from a thickness-center of the impeller toward both thickness-ends of the impeller forwardly with respect to the rotative direction,
• the thickness-center and each of the thickness-ends are connected via a second line segment, which defines a forward inclining angle β being an acute angle with respect to a first straight line, which is tangent to a circumscribed circle of an outer circumferential periphery of the impeller, and
• the backward inclining angle α and the forward inclining angle β satisfy the following relationships:
• 15°≦α≦30°;
• β≦60°;
• and 1≦β/α≦4.

A fluid pump comprising:

• a case member that has an inlet port and a pump passage;
• and
• an impeller that is rotatable in the case member, the impeller having a plurality of vane grooves along the pump passage extending along a rotative direction of the impeller, each vane groove being defined by a back surface on a backside with respect to the rotative direction,
• at least a radially inner side of the back surface is outwardly inclined backwardly with respect to the rotative direction,
• the back surface has a radially inner end and a radially outer end, which are connected via a first line segment, which defines a backward inclining angle α being an acute angle with respect to a radius of the impeller,
• the back surface on a side of the inlet port is inclined from a thickness-center of the impeller toward the inlet port forwardly with respect to the rotative direction,
• the case member has a communication wall that defines a communication passage communicating the inlet port with the pump passage,
• the communication wall has an inlet-side end and a passage-side end that are connected via an inclining straight line, which is gradually elevated from the inlet port toward the pump passage,
• the inclining straight line defines an angle ε being one of a right angle and an obtuse angle with respect to a second line segment, which extends from the thickness-center of the back surface to the inclining straight line through the inlet-side end of the back surface, and
• the angle ε satisfies the following relationship:
• 90°≦ε≦130°.