Dishwasher Rack Lift Mechanism

Abstract

A rack lifting assembly for a dishwasher appliance is provided. The rack lifting assembly includes a lower rack suspended within the wash chamber by one or more linkage arms. A biasing assembly is configured for rotating the linkage arms to swing the lower rack up and out of the wash chamber. The rack lifting assembly may further include a slide assembly that couples the lower rack to the linkage arms such that the lower rack may extend in the transverse direction.

What is claimed is: 
     
         1 . A dishwasher appliance defining a vertical, a lateral, and a transverse direction, the dishwasher appliance comprising:
 a wash tub that defines a wash chamber;   a fluid circulation assembly for providing a fluid flow for cleaning articles placed within the wash chamber; and   a lower rack lifting assembly comprising:
 a lower rack configured for receipt of the articles for washing; 
 a linkage arm having a first end and a second end, the first end being rotatably mounted to the lower rack; and 
 a biasing assembly operably coupled to the second end of the linkage arm, the biasing assembly being configured for rotating the linkage arm about the second end to swing the lower rack up and out of the wash chamber. 
   
     
     
         2 . The dishwasher appliance of  claim 1 , wherein the linkage arm is a first linkage arm, the lower rack lifting assembly further comprising:
 a second linkage arm having a first end and a second end, the first end being rotatably mounted to the lower rack and the second end being rotatably mounted to the wash tub; and   a connecting arm attached to the first end of the first linkage arm and the first end of the second linkage arm, thereby forming a four bar linkage system.   
     
     
         3 . The dishwasher appliance of  claim 1 , wherein the lower rack lifting assembly further comprises a slide assembly, the slide assembly slidably coupling the lower rack to the linkage arm to allow the lower rack to extend in the transverse direction relative to the linkage arm. 
     
     
         4 . The dishwasher appliance of  claim 3 , wherein the slide assembly comprises a slide fixed to the lower rack and a guide fixed to the first end of the linkage arm such that the slide may be received in the guide. 
     
     
         5 . The dishwasher appliance of  claim 1 , wherein the biasing assembly comprises:
 a support bracket;   a geared rack slidably mounted to the support bracket;   a pinion gear coupled to the linkage arm and rotatably mounted to the support bracket such that the pinion gear engages the geared rack; and   a biasing member configured to urge the geared rack to slide within the support bracket, thereby rotating the pinion gear and the linkage arm.   
     
     
         6 . The dishwasher appliance of  claim 5 , wherein the biasing member is one or more springs, wherein the one or more springs are in compression when the lower rack is in a lowered position within the wash chamber. 
     
     
         7 . The dishwasher appliance of  claim 5 , wherein the biasing assembly defines a longitudinal axis that corresponds to a direction of motion of the geared rack, the longitudinal axis being inclined relative to the transverse direction. 
     
     
         8 . The dishwasher appliance of  claim 5 , wherein the biasing member is a gas spring or a hydraulic cylinder. 
     
     
         9 . The dishwasher appliance of  claim 1 , wherein the biasing assembly comprises a motor configured for rotating the linkage arm about the second end of the linkage arm. 
     
     
         10 . The dishwasher appliance of  claim 1 , wherein the lower rack lifting assembly is a first rack lifting assembly disposed at a first lateral side of the lower rack, the dishwasher appliance further comprising a second rack lifting assembly disposed at a second lateral side of the lower rack. 
     
     
         11 . The dishwasher appliance of  claim 10 , wherein a stopper bracket extends along the lateral direction and is connected between the first rack lifting assembly and the second rack lifting assembly, the stopper bracket configured for contacting a back wall of the wash chamber when the lower rack is in a lowered position. 
     
     
         12 . A rack lifting assembly for a dishwasher appliance defining a vertical, a lateral, and a transverse direction, the rack lifting assembly comprising:
 a lower rack configured for receipt of articles for washing;   a slide assembly slidably coupled to the lower rack to allow the lower rack to extend in the transverse direction;   a linkage arm having a first end and a second end, the first end being rotatably mounted to the slide assembly; and   a biasing assembly operably coupled to the second end of the linkage arm, the biasing assembly being configured for rotating the linkage arm about the second end to swing the lower rack up and out of the wash chamber.   
     
     
         13 . The rack lifting assembly of  claim 12 , wherein the linkage arm is a first linkage arm, the lower rack lifting assembly further comprising:
 a second linkage arm having a first end and a second end, the first end being rotatably mounted to the slide assembly and the second end being rotatably mounted to the wash tub; and   a connecting arm attached to the first end of the first linkage arm and the first end of the second linkage arm, thereby forming a four bar linkage system.   
     
     
         14 . The rack lifting assembly of  claim 12 , wherein the slide assembly comprises a slide fixed to the lower rack and a guide fixed to the first end of the linkage arm such that the slide may be received in the guide. 
     
     
         15 . The rack lifting assembly of  claim 12 , wherein the biasing assembly comprises:
 a support bracket;   a geared rack slidably mounted to the support bracket;   a pinion gear coupled to the linkage arm and rotatably mounted to the support bracket such that the pinion gear engages the geared rack; and   a biasing member configured to urge the geared rack to slide within the support bracket, thereby rotating the pinion gear and the linkage arm.   
     
     
         16 . The rack lifting assembly of  claim 15 , wherein the biasing member is one or more springs, wherein the one or more springs are in compression when the lower rack is in a lowered position within the wash chamber. 
     
     
         17 . The rack lifting assembly of  claim 15 , wherein the biasing assembly defines a longitudinal axis that corresponds to a direction of motion of the geared rack, the longitudinal axis being inclined relative to the transverse direction. 
     
     
         18 . The rack lifting assembly of  claim 12 , wherein the biasing assembly comprises a motor configured for rotating the linkage arm about the second end of the linkage arm. 
     
     
         19 . The rack lifting assembly of  claim 12 , wherein the lower rack lifting assembly is a first rack lifting assembly disposed at a first lateral side of the lower rack, the dishwasher appliance further comprising a second rack lifting assembly disposed at a second lateral side of the lower rack. 
     
     
         20 . The rack lifting assembly of  claim 19 , wherein a stopper bracket extends along the lateral direction and is connected between the first rack lifting assembly and the second rack lifting assembly, the stopper bracket configured for contacting a back wall of the wash chamber when the lower rack is in a lowered position.