Gear Pump

Abstract

A gear pump includes: a pump chamber formed in the housing; a gear disposed in the pump chamber; a side plate disposed between a wall of the pump chamber and the gear, and arranged to seal a side surface of the gear, the side plate including an annular receiving portion formed between the wall of the pump chamber and the side plate, the receiving portion having a bottom portion and a side wall portion; a seal member disposed in the receiving portion of the side plate, and arranged to liquid-tightly separate the low pressure chamber and the high pressure chamber of the pump chamber; a pressure introducing section arranged to introduce a pressure generated by the pump operation, to a space between the bottom portion of the receiving portion and the seal member, and thereby to separate the seal member away from the bottom portion of the receiving portion.

1 . A gear pump comprising:
 a housing;   a pump chamber formed in the housing, the pump chamber having a low pressure chamber and a high pressure chamber;   a gear disposed in the pump chamber, and arranged to be driven by a motor to perform a pump operation;   a side plate disposed between a wall of the pump chamber and the gear, and arranged to seal a side surface of the gear, the side plate including an annular receiving portion formed between the wall of the pump chamber and the side plate, the receiving portion having a bottom portion and a side wall portion;   a seal member disposed in the receiving portion of the side plate, and arranged to liquid-tightly separate the low pressure chamber and the high pressure chamber of the pump chamber;   a pressure introducing section arranged to introduce a pressure generated by the pump operation, to a space between the bottom portion of the receiving portion and the seal member, and thereby to separate the seal member away from the bottom portion of the receiving portion.   
     
     
         2 . The gear pump as claimed in  claim 1 , wherein the seal member is disposed with a clearance between the seal member the bottom portion of the receiving portion; and the pressure guide section is arranged to introduce the pressure from the high pressure chamber to the clearance. 
     
     
         3 . The gear pump as claimed in  claim 2 , wherein the side wall portion of the receiving portion includes a holding portion arranged to abut on the seal member, and thereby to hold the seal member in a predetermined position, and a plurality of the pressure introducing sections provided alternatively in the holding portion of the side wall portion of the receiving portion; and the pressure introducing section has a width larger than a width of the holding portion with respect to the bottom portion. 
     
     
         4 . The gear pump as claimed in  claim 3 , wherein the side plate is made from a resin; and the holding portion and the pressure introducing section are integrally formed. 
     
     
         5 . The gear pump as claimed in  claim 1 , wherein the gear pump further comprises a center plate fixed within the housing, and a pair of pump chambers including the pump chamber; the pump chambers are disposed on both sides of the center plate to sandwich the center plate; the gear is disposed between the center plate and the side plate; the gear includes a drive gear arranged to rotate by the motor, and a driven gear arranged to be engaged with the drive gear, and to be driven by the drive gear; and the gear is a tandem external gear. 
     
     
         6 . The gear pump as claimed in  claim 2 , wherein the gear pump further comprises a communicating groove formed in the side plate, and arranged to communicate the clearance and the high pressure chamber. 
     
     
         7 . The gear pump as claimed in  claim 6 , wherein the gear pump is used for a brake apparatus for a vehicle; the brake apparatus includes a reservoir arranged to receive a brake fluid from a wheel cylinder at an ABS pressure decreasing control; the gear pump is connected through the reservoir to the wheel cylinder at the ABS pressure decreasing control, so that the pump chamber receives the pressure of the wheel cylinder; the pressure of the wheel cylinder is acted to the low pressure chamber; the seal member is transformed by the pressure of the wheel cylinder so that the pressure of the wheel cylinder is acted through the communicating groove to the high pressure chamber in accordance with the transformation. 
     
     
         8 . The gear pump as claimed in  claim 2 , wherein the seal member includes an elastic transformation portion arranged to elastically transform, and a backup portion arranged to reinforce the elastic transformation portion; and the backup portion of the seal member confronts a boundary between the low pressure chamber and the high pressure chamber. 
     
     
         9 . A gear pump comprising:
 a housing;   a pump chamber formed in the housing, the pump chamber having a high pressure chamber and a low pressure chamber;   a gear disposed within the pump chamber, and arranged to rotate at least by a drive shaft;   a side plate disposed adjacent to the gear, between a side surface of the gear and a wall of the pump chamber, the side plate having an annular recessed groove formed in a surface confronting the wall of the pump chamber, and the annular recessed groove having a bottom portion; and   a seal member disposed in the annular recessed groove of the side plate, and arranged to separate the high pressure chamber and the low pressure chamber of the pump chamber, and to be pushed in a direction away from the bottom portion of the recessed groove by a pressure introduced from the high pressure chamber when the gear is driven.   
     
     
         10 . The gear pump as claimed in  claim 9 , wherein the seal member is disposed with a clearance between the seal member and the bottom portion of the recessed groove; and the high pressure chamber is arranged to introduce the pressure to the clearance. 
     
     
         11 . The gear pump as claimed in  claim 10 , wherein the recessed groove of the side plate includes a side wall portion disposed on the high pressure chamber's side; and the side wall portion of the recessed groove includes a holding portion arranged to abut on the seal member, and to hold the seal member in a predetermined position, and a plurality of pressure introducing sections provided alternatively in the holding portion; and each of the pressure guide sections of the side wall portion has a width larger than a width of the holding portion with respect to the bottom portion to introduce the pressure of the high pressure chamber to the clearance. 
     
     
         12 . The gear pump as claimed in  claim 11 , wherein the side plate is made of a resin; and the recessed groove, the holding portion, and the pressure introducing section are integrally formed. 
     
     
         13 . The gear pump as claimed in  claim 10 , wherein the side plate includes a communicating groove connecting the clearance and the high pressure chamber. 
     
     
         14 . The gear pump as claimed in  claim 10 , wherein the seal member includes an elastic transformation portion arranged to elastically transform, and a backup portion arranged to reinforce the elastic transformation portion; and the backup portion confronts a boundary between the high pressure chamber and the low pressure chamber. 
     
     
         15 . The gear pump as claimed in  claim 10 , wherein the gear pump further comprises a center plate fixed within the housing, and a pair of pump chambers including the pump chamber; the pump chambers are disposed both sides of the center plate to sandwich the center plate; the gear is disposed between the center plate and the side plate; and the gear includes a drive gear driven by the drive shaft, and a driven gear arranged to be engaged with the drive gear, and to be driven by the drive gear; and the gear pump is a tandem external gear. 
     
     
         16 . A gear pump comprising:
 at least a pair of gears engaged with each other;   a side plate disposed adjacent to the gears, the side plate including an annular recessed groove, and a shoulder portion;   a housing disposed at a position to sandwich the side plate with the gear, and to confront the gear;   a seal member disposed in the annular recessed groove of the side plate, and arranged to seal a gap between the housing and an end of the shoulder portion of the side plate, and to separate a low pressure chamber and a high pressure chamber formed in a radial direction of the gear; and   a pressure introducing section arranged to transform the seal member by a pressure of the high pressure chamber in a direction toward the end of the shoulder portion.   
     
     
         17 . The gear pump as claimed in  claim 16 , wherein the seal member is disposed with a clearance between the seal member and the bottom portion of the recessed portion of the side plate; and the pressure introducing section is arranged to introduce the pressure of the high pressure portion to the clearance. 
     
     
         18 . The gear pump as claimed in  claim 17 , wherein the recessed portion of the side plate includes a side wall portion on the high pressure chamber's side; the side wall portion of the recessed portion includes a holding portion arranged to abut on the seal member, and to hold the seal member in a predetermined position, and a plurality of the pressure guide sections provided alternatively in the holding portion, and which has a width larger than the bottom portion of the recessed portion; the side plate is made of a resin; and the recessed groove, the holding portion, the pressure introducing sections are integrally formed. 
     
     
         19 . The gear pump as claimed in  claim 16 , wherein the gear pump further comprises a center plate fixed within the housing, and a pair of pump chambers; the pump chambers are disposed on both sides of the center plate to sandwich the center plate; the gear is disposed between the center plate and the side plate; the gear includes a drive gear driven by the motor, and a driven gear arranged to be engaged with the drive gear, and to be driven by the drive gear; and the gear is a tandem external gear. 
     
     
         20 . The gear pump as claimed in  claim 17 , wherein the side plate includes a communicating groove connecting the clearance and the high pressure chamber.