Stabilizer leg arrangement and method for detecting whether or not a stabilizer leg is in supporting contact with the ground
A stabilizer leg arrangement with a stabilizer leg ( 25 ), which is extensible by a hydraulic cylinder ( 27 ) into a supporting position in contact with the ground. A piston ( 32 ) divides the internal space of the hydraulic cylinder into first and second chambers ( 34, 35 ), wherein these chambers are configured to come into fluid communication with each other through a flow channel ( 41 ) in the hydraulic cylinder when the piston reaches an advanced end position and abuts against a stop surface. An electronic control device ( 72 ) is configured to establish information as to whether or not the stabilizer leg is in the supporting position while taking into account a measuring value (V 1 ) related to the hydraulic pressure in the first chamber ( 34 ). The invention also relates to a corresponding method and a mobile working machine comprising such a stabilizer leg arrangement.
1. A stabilizer leg arrangement comprising a support structure ( 20 ) and a stabilizer leg ( 25 ) carried by the support structure ( 20 ), the stabilizer leg ( 25 ) being provided with a hydraulic cylinder ( 27 ), by which the stabilizer leg ( 25 ) is extensible in a vertical direction in relation to the support structure ( 20 ) from a raised inactive position, in which the stabilizer leg ( 25 ) is out of contact with the ground, to an active supporting position, in which the stabilizer leg ( 25 ) is in supporting contact with the ground, wherein
the hydraulic cylinder ( 27 ) comprises:
a cylinder housing ( 30 ) having an internal space ( 33 ),
a piston ( 32 ) movably received in said internal space ( 33 ) and configured to divide this space ( 33 ) into a first chamber ( 34 ) on a first side of the piston ( 32 ) and a second chamber ( 35 ) on an opposite second side of the piston ( 32 ), and
a piston rod ( 31 ) fixed to the piston ( 32 ) and extending through the second chamber ( 35 ), the piston ( 32 ) being moveable in relation to the cylinder housing ( 30 ) to an advanced end position, in which the piston ( 32 ) abuts against a stop surface ( 40 ) at a lower end of the internal space ( 33 ) and in which the second chamber ( 35 ) has its minimum volume;
the stabilizer leg arrangement ( 2 ) further comprises a pressure sensor ( 70 ) configured to generate a measuring value (V 1 ) representing the hydraulic pressure in said first chamber ( 34 ), and an electronic control device ( 72 ) connected to the pressure sensor ( 70 ), wherein the electronic control device ( 72 ) is configured to establish information whether or not the stabilizer leg ( 25 ) is in the active supporting position while taking into account said measuring value (V 1 );
the second chamber ( 35 ) is configured to come into fluid communication with the first chamber ( 34 ) through at least one flow channel ( 41 ; 41 ′; 41 ″) in the hydraulic cylinder ( 27 ) when the piston ( 32 ) reaches the advanced end position or is on the verge of reaching this end position; and the piston ( 32 ) is configured to keep the second chamber ( 35 ) fluidly separated from the first chamber ( 34 ) when the piston is in any other position in relation to the cylinder housing ( 30 ).
2. A stabilizer leg arrangement according to claim 1 , wherein said flow channel ( 41 ) extends through the piston ( 32 ), the piston ( 32 ) is provided with a valve member ( 42 ), which is moveable between a closed position, in which the valve member ( 42 ) is configured to prevent fluid flow through the flow channel ( 41 ), and an open position, in which the valve member ( 42 ) is configured to allow fluid flow through the flow channel ( 41 ), and the valve member ( 42 ) is configured to be automatically moved to the open position when the piston ( 32 ) reaches or is on the verge of reaching the advanced end position.
3. A stabilizer leg arrangement according to claim 2 , wherein the valve member ( 42 ) is moveable from the closed position to the open position against the action of a spring member ( 43 ) and from the open position to the closed position by the action of the spring member ( 43 ).
4. A stabilizer leg arrangement according to claim 3 , wherein the valve member ( 42 ) comprises:
a head part ( 44 ), which is configured to be in fluid-tight contact with a valve seat ( 45 ) when the valve member ( 42 ) is in the closed position and thereby prevent fluid flow through the flow channel ( 41 ); and
an elongated stem part ( 46 ), which is fixed to the head part ( 44 ) and extends through said flow channel ( 41 ), wherein the stem part ( 46 ) is configured to come into contact with a stop ( 47 ) at the lower end of the internal space ( 33 ) when the piston ( 32 ) is on the verge of reaching the advanced end position to thereby push the head part ( 44 ) away from the valve seat ( 45 ).
5. A stabilizer leg arrangement according to claim 4 , wherein the first and second chambers ( 34 , 35 ) of the hydraulic cylinder ( 27 ) are connected to a directional control valve ( 83 ) of a hydraulic system ( 80 ) included in the stabilizer leg arrangement ( 2 ), the hydraulic system ( 80 ) comprising a hydraulic fluid reservoir ( 81 ) and a pump ( 82 ) for pumping hydraulic fluid from the reservoir ( 81 ) to a pressure port (P) of the directional control valve ( 83 ), and the directional control valve ( 83 ) has a return port (R) connected to the reservoir ( 81 ), the directional control valve ( 83 ) being provided with a valve spool ( 88 ), which is moveable between:
a first working position, in which the pressure port (P) is connected to the first chamber ( 34 ) and the return port (R) is connected to the second chamber ( 35 ),
a second working position, in which the pressure port (P) is connected to the second chamber ( 35 ) and the return port (R) is connected to the first chamber ( 34 ), and
a normal position, in which the pressure port (P) is disconnected from the first and second chambers ( 34 , 35 ).
6. A stabilizer leg arrangement according to claim 3 , wherein the first and second chambers ( 34 , 35 ) of the hydraulic cylinder ( 27 ) are connected to a directional control valve ( 83 ) of a hydraulic system ( 80 ) included in the stabilizer leg arrangement ( 2 ), the hydraulic system ( 80 ) comprising a hydraulic fluid reservoir ( 81 ) and a pump ( 82 ) for pumping hydraulic fluid from the reservoir ( 81 ) to a pressure port (P) of the directional control valve ( 83 ), and the directional control valve ( 83 ) has a return port (R) connected to the reservoir ( 81 ), the directional control valve ( 83 ) being provided with a valve spool ( 88 ), which is moveable between:
a first working position, in which the pressure port (P) is connected to the first chamber ( 34 ) and the return port (R) is connected to the second chamber ( 35 ),
a second working position, in which the pressure port (P) is connected to the second chamber ( 35 ) and the return port (R) is connected to the first chamber ( 34 ), and
a normal position, in which the pressure port (P) is disconnected from the first and second chambers ( 34 , 35 ).
7. A stabilizer leg arrangement according to claim 2 , wherein the valve member ( 42 ) comprises:
a head part ( 44 ), which is configured to be in fluid-tight contact with a valve seat ( 45 ) when the valve member ( 42 ) is in the closed position and thereby prevent fluid flow through the flow channel ( 41 ); and
an elongated stem part ( 46 ), which is fixed to the head part ( 44 ) and extends through said flow channel ( 41 ), wherein the stem part ( 46 ) is configured to come into contact with a stop ( 47 ) at the lower end of the internal space ( 33 ) when the piston ( 32 ) is on the verge of reaching the advanced end position to thereby push the head part ( 44 ) away from the valve seat ( 45 ).
8. A stabilizer leg arrangement according to claim 7 , wherein the first and second chambers ( 34 , 35 ) of the hydraulic cylinder ( 27 ) are connected to a directional control valve ( 83 ) of a hydraulic system ( 80 ) included in the stabilizer leg arrangement ( 2 ), the hydraulic system ( 80 ) comprising a hydraulic fluid reservoir ( 81 ) and a pump ( 82 ) for pumping hydraulic fluid from the reservoir ( 81 ) to a pressure port (P) of the directional control valve ( 83 ), and the directional control valve ( 83 ) has a return port (R) connected to the reservoir ( 81 ), the directional control valve ( 83 ) being provided with a valve spool ( 88 ), which is moveable between:
a first working position, in which the pressure port (P) is connected to the first chamber ( 34 ) and the return port (R) is connected to the second chamber ( 35 ),
a second working position, in which the pressure port (P) is connected to the second chamber ( 35 ) and the return port (R) is connected to the first chamber ( 34 ), and
a normal position, in which the pressure port (P) is disconnected from the first and second chambers ( 34 , 35 ).
9. A stabilizer leg arrangement according to claim 2 , wherein the first and second chambers ( 34 , 35 ) of the hydraulic cylinder ( 27 ) are connected to a directional control valve ( 83 ) of a hydraulic system ( 80 ) included in the stabilizer leg arrangement ( 2 ), the hydraulic system ( 80 ) comprising a hydraulic fluid reservoir ( 81 ) and a pump ( 82 ) for pumping hydraulic fluid from the reservoir ( 81 ) to a pressure port (P) of the directional control valve ( 83 ), and the directional control valve ( 83 ) has a return port (R) connected to the reservoir ( 81 ), the directional control valve ( 83 ) being provided with a valve spool ( 88 ), which is moveable between:
a first working position, in which the pressure port (P) is connected to the first chamber ( 34 ) and the return port (R) is connected to the second chamber ( 35 ),
a second working position, in which the pressure port (P) is connected to the second chamber ( 35 ) and the return port (R) is connected to the first chamber ( 34 ), and
a normal position, in which the pressure port (P) is disconnected from the first and second chambers ( 34 , 35 ).
10. A stabilizer leg arrangement according to claim 1 , wherein said flow channel ( 41 ′) is formed as an axial groove in an inner wall ( 38 ) of the cylinder housing ( 30 ).
11. A stabilizer leg arrangement according to claim 10 , wherein the first and second chambers ( 34 , 35 ) of the hydraulic cylinder ( 27 ) are connected to a directional control valve ( 83 ) of a hydraulic system ( 80 ) included in the stabilizer leg arrangement ( 2 ), the hydraulic system ( 80 ) comprising a hydraulic fluid reservoir ( 81 ) and a pump ( 82 ) for pumping hydraulic fluid from the reservoir ( 81 ) to a pressure port (P) of the directional control valve ( 83 ), and the directional control valve ( 83 ) has a return port (R) connected to the reservoir ( 81 ), the directional control valve ( 83 ) being provided with a valve spool ( 88 ), which is moveable between:
a first working position, in which the pressure port (P) is connected to the first chamber ( 34 ) and the return port (R) is connected to the second chamber ( 35 ),
a second working position, in which the pressure port (P) is connected to the second chamber ( 35 ) and the return port (R) is connected to the first chamber ( 34 ), and
a normal position, in which the pressure port (P) is disconnected from the first and second chambers ( 34 , 35 ).
12. A stabilizer leg arrangement according to claim 1 , wherein the first and second chambers ( 34 , 35 ) of the hydraulic cylinder ( 27 ) are connected to a directional control valve ( 83 ) of a hydraulic system ( 80 ) included in the stabilizer leg arrangement ( 2 ), the hydraulic system ( 80 ) comprising a hydraulic fluid reservoir ( 81 ) and a pump ( 82 ) for pumping hydraulic fluid from the reservoir ( 81 ) to a pressure port (P) of the directional control valve ( 83 ), and the directional control valve ( 83 ) has a return port (R) connected to the reservoir ( 81 ), the directional control valve ( 83 ) being provided with a valve spool ( 88 ), which is moveable between:
a first working position, in which the pressure port (P) is connected to the first chamber ( 34 ) and the return port (R) is connected to the second chamber ( 35 ),
a second working position, in which the pressure port (P) is connected to the second chamber ( 35 ) and the return port (R) is connected to the first chamber ( 34 ), and
a normal position, in which the pressure port (P) is disconnected from the first and second chambers ( 34 , 35 ).
13. A stabilizer leg arrangement according to claim 12 , wherein the second chamber ( 35 ) is disconnected from the reservoir ( 81 ) in the normal position of the valve spool ( 88 );
the stabilizer leg arrangement ( 2 ) comprises another pressure sensor ( 71 ) configured to generate a measuring value (V 2 ) representing the hydraulic pressure in the second chamber ( 35 ); and
the electronic control device ( 72 ) is configured to establish that the stabilizer leg ( 25 ) is in the active supporting position if it is established by the electronic control device the following conditions are simultaneously fulfilled:
the differential pressure (Pdiff) in the hydraulic cylinder ( 27 ) is higher than a given threshold value (Vth), and
the measuring value (V 1 ) representing the hydraulic pressure in the first chamber ( 34 ) differs from the measuring value (V 2 ) representing the hydraulic pressure in the second chamber ( 35 ).
14. A stabilizer leg arrangement according to claim 12 , wherein the return port (R) of the directional control valve ( 83 ) is disconnected from the second chamber ( 35 ) in the normal position of the valve spool ( 88 );
that the hydraulic system comprises a bypass line ( 90 ) configured to form a connection between the second chamber ( 35 ) and the reservoir, and a control valve ( 91 ) arranged in the bypass line ( 90 ), wherein the control valve ( 91 ) is shiftable between a closed position, in which the control valve ( 91 ) is configured to prevent fluid flow through the bypass line ( 90 ), and an open position, in which the second chamber ( 35 ) is in fluid communication with the reservoir ( 81 ) through the bypass line ( 90 ); and
the electronic control device ( 72 ) is configured to control the control valve ( 91 ) to assume the open position at the moment when the electronic control device ( 72 ) establishes the information whether or not the stabilizer leg ( 25 ) is in the active supporting position.
15. A stabilizer leg arrangement according to claim 12 , wherein the return port (R) of the directional control valve ( 83 ) is connected to the second chamber ( 35 ) in the normal position of the valve spool ( 88 ).
16. A mobile working machine with a chassis ( 5 ), wherein the mobile working machine ( 1 ) comprises a stabilizer leg arrangement ( 2 ) according to claim 1 , and the support structure ( 20 ) of the stabilizer leg arrangement ( 2 ) is connected to the chassis ( 5 ).
17. A mobile working machine according to claim 16 , wherein the mobile working machine ( 1 ) comprises a hydraulic crane ( 4 ) mounted to the chassis ( 5 ).
18. A method for detecting whether or not a stabilizer leg ( 25 ) is in an active supporting position in supporting contact with the ground, the stabilizer leg ( 25 ) being extensible in a vertical direction in relation to a support structure ( 20 ) by hydraulic cylinder ( 27 ) from a raised inactive position, in which the stabilizer leg ( 25 ) is out of contact with ground, to said active supporting position, said hydraulic cylinder ( 27 ) comprising:
a cylinder housing ( 30 ) having an internal space ( 33 ),
a piston ( 32 ) movably received in said internal space ( 33 ) and configured to divide this space ( 33 ) into a first chamber ( 34 ) on a first side of the piston ( 32 ) and a second chamber ( 35 ) on an opposite second side of the piston ( 32 ), and
a piston rod ( 31 ) fixed to the piston ( 32 ) and extending through the second chamber ( 35 ), the piston ( 32 ) being moveable in relation to the cylinder housing ( 30 ) to an advanced end position, in which the piston ( 32 ) abuts against a stop surface ( 40 ) at a lower end of the internal space ( 33 ) and in which the second chamber ( 35 ) has its minimum volume;
wherein:
a pressure sensor ( 70 ) generates a measuring value (V 1 ) representing the hydraulic pressure in said first chamber ( 34 );
the second chamber ( 35 ) is made to come into fluid communication with the first chamber ( 34 ) through at least one flow channel ( 41 ; 41 ′; 41 ″) in the hydraulic cylinder ( 27 ) when the piston ( 32 ) reaches the advanced end position or is on the verge of reaching this end position, the piston ( 32 ) keeping the second chamber ( 35 ) fluidly separated from the first chamber ( 34 ) when the piston ( 32 ) is in any other position in relation to the cylinder housing ( 30 ); and
information s to whether or not the stabilizer leg ( 25 ) is in the active supporting position is established by an electronic control device ( 72 ) while taking into account said measuring value (V 1 ).
19. A method according to claim 18 , wherein the electronic control device ( 72 ), at the moment when it establishes information whether or not the stabilizer leg ( 25 ) is in the active supporting position, controls a control valve ( 91 ) in a line ( 90 ) between the second chamber ( 35 ) and a hydraulic fluid reservoir ( 81 ) to assume an open position to thereby bring the second chamber ( 35 ) into fluid communication with the reservoir ( 81 ) through this line ( 90 ).
20. A method according to claim 18 , wherein another pressure sensor ( 71 ) generates a measuring value (V 2 ) representing the hydraulic pressure in said second chamber ( 35 ); that the electronic control device ( 72 ) establishes the magnitude of the differential pressure (Pdiff) in the hydraulic cylinder ( 27 ) based on said measuring values (V 1 , V 2 ); and
the electronic control device ( 72 ) establishes that the stabilizer leg ( 25 ) is in the active supporting position if the following conditions are simultaneously fulfilled:
the differential pressure (Pdiff) in the hydraulic cylinder ( 27 ) is higher than a given threshold value (Vth), and
the measuring value (V 1 ) representing the hydraulic pressure in the first chamber ( 34 ) differs from the measuring value (V 2 ) representing the hydraulic pressure in the second chamber ( 35 ).