Open hydraulic fluid flow circuit arrangement and method of controlling the hydraulic circuit

Abstract

The invention relates to a fluid flow arrangement ( 1, 15 ) with an adjustable fluid pumping device ( 2 ) and a fluid working machine ( 12 ). The fluid working machine ( 12 ) is connected to the fluid pumping device ( 2 ) and a re-circulating loop is provided for the fluid working machine ( 12 ). The re-circulating loop is fluidly connecting a first fluid port (A) and a second fluid port (B) of the fluid working machine ( 12 ), where the first (A) and the second fluid port (B) are at times at a different pressure level. The re-circulating loop comprises a controllable fluid throttling device ( 21, 22 ), and a switchable fluid conduit device ( 23, 24 ), so that a defined decelerating force can be generated for the fluid working machine ( 12 ).

What is claimed is: 
     
         1 . A fluid flow arrangement, comprising a preferably adjustable fluid pumping device, a fluid working machine fluidly connected to said fluid pumping device and a re-circulating loop, fluidly connecting a first fluid port (A) and a second fluid port (B) of said fluid working machine, where said first (A) and said second fluid port (B) are preferably at times at a different pressure level, wherein the re-circulating loop comprises a controllable fluid throttling device, and a switchable fluid conduit device. 
     
     
         2 . The fluid flow arrangement according to  claim 1 , wherein said re-circulating loop can be circulated in opposing directions, in particular in that it comprises at least two controllable fluid throttling devices and/or at least two switchable fluid conduit devices. 
     
     
         3 . The fluid flow arrangement according to  claim 1 , wherein said adjustable fluid pumping device and said fluid working machine are connected using at least one fluid switching means in particular in a way that the output of said fluid pumping device can be selectively connected to at least one of said at least two different fluid ports (A, B) of said fluid working machine, in particular to one of said first (A) and said second fluid port (B) of said fluid working machine. 
     
     
         4 . The fluid flow arrangement according to  claim 1 , wherein said fluid flow arrangement is an open hydraulic fluid flow circuit, in particular for propelling purposes. 
     
     
         5 . The fluid flow arrangement according to  claim 1 , wherein at least one of said controllable fluid throttling devices is a pressure relief valve with a preferably adjustable set point. 
     
     
         6 . The fluid flow arrangement according to  claim 5 , in particular according to  claim 5 , wherein said controllable fluid throttling device is an electrically controllable device and/or in that said controllable fluid throttling device is controlled by an electronic controlling device, in particular a programmable electronic controlling device. 
     
     
         7 . The fluid flow arrangement according to  claim 1 , wherein said at least one of said controllable fluid conduit devices is a directional valve, in particular a check valve and/or in that at least one of said controllable fluid conduit devices shows a defined pressure loss behaviour over said fluid conduit device that is dependent on the fluid flow rate through said fluid conduit device. 
     
     
         8 . The fluid flow arrangement according to  claim 1 , characterized by wherein at least one pressure measuring device, in particular a plurality of pressure measuring devices that are preferably arranged at the re-circulating loop, more preferably between a fluid port (A, B) of said fluid working machine and at least one of said controllable fluid throttling devices and/or between at least two of said controllable fluid throttling devices and/or at the fluid output line of said preferably adjustable fluid pumping device. 
     
     
         9 . An electronic controlling device for controlling a fluid flow arrangement, in particular for controlling a fluid flow arrangement according to  claim 1 , wherein said fluid flow arrangement comprises at least one fluid working machine, at least a re-circulating loop, fluidly connecting a first fluid port (A) and a second fluid port (B) of a fluid working machine, and at least one controllable fluid throttling device that is arranged in said re-circulating loop, characterized in that said electronic controlling device generates a control signal for said at least one controllable fluid throttling device in a way to generate a defined decelerating force for said fluid working machine. 
     
     
         10 . The electronic controlling device according to  claim 9 , wherein at least one sensor signal, describing the current state of the fluid flow arrangement, is used for generating said control signal, in particular in that pressure data is used for generating said control signal. 
     
     
         11 . The electronic controlling device according to  claim 9 , wherein said control signal is generated in a way that the fluid flow arrangement can be operated in at least one mode, taken from the group comprising: a method, in which the speed of the fluid working machine is controlled by outputting an appropriate control signal to control the pressure at an outlet port of the fluid working machine, while the fluid working machine is not driven by a fluid pumping device; a method, in which the speed of the fluid working machine is controlled by outputting an appropriate control signal to control the pressure at the outlet port of the fluid working machine, while the fluid working machine is driven, at least in part, by a fluid pumping device; and a method, where the turning direction of the fluid working machine is reversed by first slowing down the speed of the fluid working machine and then switching a fluid switching means in a way that the output of a fluid pumping device is selectively connected to a different fluid port of said fluid working machine. 
     
     
         12 . A fluid flow arrangement comprising a preferably adjustable fluid pumping device, a fluid working machine fluidly connected to said fluid pumping device and a re-circulating loop, fluidly connecting a first fluid port (A) and a second fluid port (B) of said fluid working machine, where said first (A) and said second fluid port (B) are preferably at times at a different pressure level, wherein the re-circulating loop comprises a controllable fluid throttling device, wherein an electronic controlling device according to  claim 9 . 
     
     
         13 . The fluid flow arrangement according to  claim 11  that is used as a propelling means for a vehicle, in particular for a land vehicle. 
     
     
         14 . The fluid flow arrangement according to  claim 2 , wherein said adjustable fluid pumping device and said fluid working machine are connected using at least one fluid switching means, in particular in a way that the output of said fluid pumping device can be selectively connected to at least one of said at least two different fluid ports (A, B) of said fluid working machine, in particular to one of said first (A) and said second fluid port (B) of said fluid working machine. 
     
     
         15 . The fluid flow arrangement according to  claim 2 , wherein said fluid flow arrangement is an open hydraulic fluid flow circuit, in particular for propelling purposes. 
     
     
         16 . The fluid flow arrangement according to  claim 3 , wherein said fluid flow arrangement is an open hydraulic fluid flow circuit, in particular for propelling purposes. 
     
     
         17 . The fluid flow arrangement according to  claim 2 , wherein at least one of said controllable fluid throttling devices is a pressure relief valve with a preferably adjustable set point. 
     
     
         18 . The fluid flow arrangement according to  claim 3 , wherein at least one of said controllable fluid throttling devices is a pressure relief valve with a preferably adjustable set point. 
     
     
         19 . The fluid flow arrangement according to  claim 4 , wherein at least one of said controllable fluid throttling devices is a pressure relief valve with a preferably adjustable set point. 
     
     
         20 . The fluid flow arrangement according to  claim 1 , wherein said controllable fluid throttling device is an electrically controllable device and/or in that said controllable fluid throttling device is controlled by an electronic controlling device, in particular a programmable electronic controlling device.