Washer pump having a pair of flow paths with the pump side of one of the flow paths being smaller than the valve chamber side of the one flow path

A washer pump configured to suck liquid stored in a tank and configured to jet the liquid to a front-side windshield and a rear-side windshield of a vehicle, the washer pump comprising:

• a motor that rotates a rotation shaft in a forward and a reverse direction;
• a housing that accommodates the motor;
• an impeller that is rotated by the motor in a first and a second direction;
• a pump chamber in which the impeller is housed;
• a front-side valve chamber in which the liquid discharged to the front-side windshield flows in response to rotation of the impeller in the first direction;
• a rear-side valve chamber in which the liquid discharged to the rear-side windshield flows in response to rotation of the impeller in the second direction;
• a switching valve for partitioning the front-side and rear-side valve chambers,
• a front-side discharge hole that is provided on one side of the switching valve in a moving direction of the switching valve and in which the liquid discharged to the front-side windshield flows;
• a rear-side discharge hole that is provided on an other side of the switching valve in the moving direction and in which the liquid discharged to the rear-side windshield flows;
• a front-side flow path provided between the pump chamber and the front-side valve chamber;
• and
• a rear-side flow path provided between the pump chamber and the rear-side valve chamber,
• wherein the pump chamber, the front-side and rear-side valve chambers, the front-side and rear-side discharge holes, and the front-side and rear-side flow paths are integrally provided respectively in the housing,
• the front-side flow path extends to the front-side discharge hole of the front-side valve chamber so that the liquid which flows out of the front-side flow path is discharged at a center portion of the front-side valve chamber,
• the rear-side flow path extends to the rear-side discharge hole of the rear-side valve chamber so that the liquid which flows out of the rear-side flow path is discharged at a center portion of the rear-side valve chamber,
• the front-side flow path includes:
• an inclined wall provided on an inside of a side wall of the housing and increasing a flow passage area from the pump chamber to the front-side valve chamber;
• and
• an opposed wall disposed so as to be opposed to the inclined wall and is provided parallel to the side wall of the housing,
• the rear-side flow path includes a pair of wall portions that are provided on the inside of the side wall of the housing, are parallel to each other, and are provided parallel to the side wall,
• the pair of wall portions has a lateral wall portion disposed outside the rear-side flow path and an inner wall portion disposed inside the rear-side flow path, the lateral and inner wall portions being parallel to each other,
• an end portion of each valve-chamber-side of the inclined wall and the opposed wall is connected to the front-side discharge hole, and an end portion of each valve-chamber-side of the wall portions is connected to the rear-side discharge hole,
• a pump chamber side of the front-side flow path is smaller than a pump chamber side of the rear-side flow path, and a front-side valve chamber side of the front-side flow path is larger than a rear-side valve chamber side of the rear-side flow path,
• a front-side curved wall portion is formed at a position facing a discharge direction of the liquid discharged from the front-side flow path in the front-side valve chamber so that diffusion of the liquid into the front-side valve chamber is suppressed and turbulent flow of the liquid in the front-side valve chamber is suppressed,
• a rear-side curved wall portion is formed at a position facing a discharge direction of the liquid discharged from the rear-side flow path in the rear-side valve chamber so that diffusion of the liquid into the rear-side valve chamber is suppressed and turbulent flow of the liquid in the rear-side valve chamber is suppressed, and
• a length of the inclined wall from the front-side valve chamber to the pump chamber is longer than a length of the inner wall portion from the rear-side valve chamber to the pump chamber.