CA1058535A - Hydraulic oil tank - Google Patents
Hydraulic oil tankInfo
- Publication number
- CA1058535A CA1058535A CA272,722A CA272722A CA1058535A CA 1058535 A CA1058535 A CA 1058535A CA 272722 A CA272722 A CA 272722A CA 1058535 A CA1058535 A CA 1058535A
- Authority
- CA
- Canada
- Prior art keywords
- tank
- compartment
- oil
- opening
- expansion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
- F15B1/26—Supply reservoir or sump assemblies
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Supply Devices, Intensifiers, Converters, And Telemotors (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An oil tank for a hydraulic system has a main compartment and an expansion compartment separated by a partition wall. The main compartment is sealed except for suction and pressure connections to the hydraulic system and a tube extending through the partition wall. One end of the tube opens in the uppermost portion of the main compartment while the other end opens in the expansion compartment below the lowest oil level occurring therein during normal operation.
An oil tank for a hydraulic system has a main compartment and an expansion compartment separated by a partition wall. The main compartment is sealed except for suction and pressure connections to the hydraulic system and a tube extending through the partition wall. One end of the tube opens in the uppermost portion of the main compartment while the other end opens in the expansion compartment below the lowest oil level occurring therein during normal operation.
Description
~:115~53S
The present invention relates to a hydraullc oil tank for a mobile hydraulic s~stem which is provided w~th a return conduit connection, a suction conduit connection, a breathing opening to allow for changes in the volume of oil in the tank resulting from the working volumes in the operation of the hydraulic system, such as piston volumes and accumulator volumes, and preferably an oil level warning device, said tank being divided into at least ~wo communicating compart-ments.
It is required of this type of ~ank that it ~s able to function satisfactorily in spite of the fact that it tips in different directions and is subjected to jolts and vibra~ions from a vehicle. The task of the tank is, among other things, to serve as an expansion s~ace for hydraulic oil since the oil volume of the hydraulic system varies during operation dependlng on whether the cylinders of the system are extended or compressed and whether the accumulators in the system are charged or not charged, and because of thermal expansion of the hydraulic oil. The tank must also serve as a location in ,the hydraulic system where the oil can be purged of air.
In mobile systems in, for example, utility vehicles the space available ~or the tank is often quite llmited and the tank must be adapted to the available space both as to ~hape and size. Thls requirement and the sloshing movements of the oil in the tank as the vehicle moves create great problems in connection with provisions for venting and breathing of the tank, whlch is required because of the varying oil volumes, and when arranging level warning means, especially if t~e tank is quite shallow. There is a great risk that the oil will flow out through the breathing opening and that the level waxning means will indicate the wrong oil level when the vehicle tips and the oil in the tank sloshes around.
~5~353~;i Previously it was attem~ted to ellminate the~e problems in fuel tanks by dividing the tank into a number of spaces which communicate with one another via throttled connections.
Such an arrangement in a hydraulic oil tank wouldl however, require a breathing opening and a level indicator for each space to assure breathing and level indlcation even when the vehicle is tipped or the oil sloshes.
The object of the present invention is to avoid these problems and create a hydraulic oil tank whose breathing and level indication function satisfactorily even when the tanX
tips or the oil sloshes.
Accordlng to the invention this is achieved with a tank which is characterized in that said tank comprises a main compartment which is normally essentially completely filled with oil during operation and an expansion compartment; that the main compartment is provided with the ~uction and return conduit connectlons and said communication with the expansion compartment but is otherwise closedj that the expansion compartment has the breathing opening and the optional level warning device; that the communication between said compart-ments comprises a duct, a first end o~ which opens into the main compartment in its uppermost space and the second end of which opens into the expansion compartment; and that said communication comprises means whiah allow flow of oil and air from the main compartment to the expansion compartment and flow of oil but not air from the expansion compartment to the main compartment.
In this arrangement the tank volume is divided into two sections. The main compartment is always kept essentially completely filled with oil, but the oil can be purged of a~r in this compartment. Oil from the main compartment and any collected air are caused by pum~ing action from inter alia the ~58535 worklng piston volumes to flow to the expansion c~mpartment which absorbs the changes in volume during operation. The expansion compartment is dimensioned only with consideration to these changes in volume and can therefore be made consider-ably smaller 50 that the problems arising from the tlpping of the tank and the sloshing of the oil wlll have considexably less effect~
The means for preventing air from flowing from the expansion compartment to the main compartment can comprise elther placing the opening of the duct in the expanslon compartment below the lowest oil level in this compartment normally occurring during operation, or it can comprise a non-return valve in the duct and an additional connection with a non-return valve below the lowest normal oil level in the expansion compartment. The non-return valve in the duct opens in the direction into the expansion compartment and the non-return valve below the oil level of the expansion compartment opens in th~ direction into the main compartment~
If the oil tank is divided into to compartments hy means of an inner dividing wall, the duct can be made as a tube which extends from the highest portion of the main chamber through the wall down into the expansion compartment and ~pens b~low the lowest normal oil level in the same. If the arrangement with non-return valves is used, one of these valves can be arranged in an opening in the intermediate wall below the normal lowest oil level in the expansion compartment. Alterna-tively the tank compartments can be completely separate and connected with one another via external ducts.
According to a further development of the invention the tank is provided with a measuring means adapted to measure the difference between the inflows and outflows to and from the tank, respectively, as well as means for comparing the measured 1~58535 difference with a predetermined maximum value for the net outflow from the tank~ I~ this value should be exceeded, this means that a break in a conduit or a leak has occurred in the hydraulic system connected to the tank. In the case where a tank is used with non-return valves in the c~nnections between the compartments, according ~o a preferred embodiment o~ the invention, a flow meter can be disposed ~n ~he ~pening ox conduit, provided with the non-~eturn valve, below the lowe~t oil level of the expansion compartment. In that ca~e ~hare the tank has a separating wall in which there is an opening with a non return valve, the non-return valve and the flow meter can be combined in the form of a plate situated in the main compartment and closing the opening and which is ~ressed against the portions o the wall surrounding the opening by a leaf spring which is a~tached to the wall on one side of the opening. The leaf spring is provided with a wire tensiometer.
As the flow varies through the opening the bending of the leaf spring varies and these bending movements are transformed by the tensiometer into electrical signals which are supplied ~o a signal interpreting device.
Two embodiments o~ the invention are desaribed below with reference to the accompanying schematic drawings, in which Fig. 1 shows in section a hydraulic oil tank according to a first embodiment. Fig. 2 shows in section a hydraulic oil tank aGcording to a second embodiment of the invention, and Fig. 3 shows in a larger scale a section through an alternative non-return valve and flow meter in the tank according to Fig. 2.
A hydraulic oil tank 1 has a return conduit connection 2 and a suction conduit connection 3 for connection to a hydraulic system tnot shown in more detail here~ of a utility vehicle on which the tank 1 is mounted. The tank also has a breathing opening 4 at the top with a ~ilter.
On the inside the tank 1 is divide~ bv a vextical intermediate wall S into a main compartment 6Ofyreater voll~e and an expansion compartment 7 of lesser volume. The conduit connections 2,3 open into the main compartment 6, and the breathing op~ning 4 oPens into the expansion compaxtment 7. The intermedia~e wall 5 extends from the bottom of the tank 1 all the way to its top and all the way between the side walls of the tank 1 ~here~y completely sepaxating ~he compartments 6 a~d 7 from one another.
A duct 8 ex~ends through the intermediate wall S, one end 9 of which duct ~ o~ens into the uPpermost portion o the main compartment 6, which is shown in the drawing as a small air pocket 10 at the top o~ the tank 1~ The opposite end ll o~ the duct 8 opens downwards into the expansion com-par~ment 70 The end 11 o~ the duct is located helow ~he lowe~t oil level, indicated by the line 12, occurin~ during normal operation of the hydraulic system. The end 11 of ~he duc~ also lies lower than a level warning means 13 disposed a short distance below the oil level 12~ which can be o~ an aP~roDriate known type~ electric for example. The highest oil leYel normally occurring in the expansion compartment 7 during normal opexation is indicated by the dashed line 14.
The hydraulic oll tank described above works in the following manner, During the operation o~ the hydraulic system connected to the hydraulic tank hydraullc oil is drawn out of the main compartment 6 via the suction co~nection 3 and is returned through the return connection 2. Any air bubbles in the oil float upwards in the ~ain compartment 6 and are collected in the small air pocket 10, which has very little volume in comparison to ~he main compartment 6. Changes in vol~me in the hydraulic system as a rffsult of operating piston rods ~5~
and accumulators causes oil to flow between the main compartment 6 and the expans~on compar~ment 7, When the oll flow through the return connection 2 is greater than through the suctlon connec~ion 3 oil and any air collected in the air pocket 10 are pushed through the duct 8 down in~o ~he expansion compartment 7. The oil level in ~he expansion com~artment 7 rises and presses air ou~ throuyh the ~rea~hlng opening 4~ ~he oil i9 also purged o~ air through this opening. If on ~he othar hand the f low through the suctiQn connect~-on 3 i~ ~reater than tha~ through the return connection 2 there will be a ne~ative pressure in the main co~partment 6, so that oil is drawn through the duct 8 rom the expansion com-partment 7. Due to the ~act that the end 11 of the duct 8 is located below the lowest normal oil level 12 in the expans~on compartment 7 air from the expansion compartment cannot flow ~nto the main co~par~ment 6. The pumping movements of the hydraullc system thus causes the small alr pocket 10 in the main compartment to be repeatedly emptied. This compart~ent ~ontains the major port~on of the oil volume of the hydraulic oil tank 1, so that t~e expansion com~artment 7 can be made narrow so ~hat tipping of the tank and sloshing moYementS
o~ the oil will have little ef~ect on the level warning means 13 and w~ll eliminate the rlsk that the oil will forc~ its way out through the brea~hing op~ning 4. Due to ~he narrownes~
o~ the expansion compartment 7, and thus its small surfaae, the height varlation of the oil level will be great for a net outflow or inflow~ This will provide a ~istinct tripping level for the level warniny means.
The embodiment o ~he invention descri~ed above has the advantage that the tank function~ without any movabl~ parts a~ all. Oil and air will flow up and down in the duc~ ~.
Under certain conditions it is uncertain whether all the ~6~
1~J5853S
air will be ~ransported to the expansion compartment. To avoid the risk of remain~ng air volume in ~he air pocket 10 the tank can be ~onstructed as shown in Pig. 2.
In Fig. 2 details which correspond to those in Fig. 1 have been given the same reerence numerals. The tank according to Fig. 2 differs from tha~ accor~ing to Fig. 1 in ~hat a non-return ~alve 15 is dispo~ed ln t~e ~uc~ 8. The non~return valve opens in t~e direction to ~he expansion compartm~nt 7 and ~s shown ~chematlcally ~s a ball valve. An openln~
16 is placed in the in~erme~iate wall 5 in ~he ~ank 1 close to the bottom, and this opening is ~rov~ded with a non-return valve 17 openlng in~o the ~ain compar~ment 6. This no~-return valve is also shown schematically as as ball valve.
The tan~ accordin~ to Fig. 2 functions in the ~ollowing manner.
~en there is an excess 10w in the return conduit 2 oil and any air collected in the air ~ocket 10 ~ill be pressed through non-return valve 15 and down through ~he duct ~
to ~he expansion co~part~ent 7. ~on-return valve 17 prevents flow through the o~éning 16. T~le oil level in the expanslon compartment 7 r~ses and the compaxtment breathes through the o~ening 4. ~en there is a greater flow ~hrough the suction conduit connection 3 oil 10ws from ~he expansion room 7 throu~h the o~ening 16 and the non-return valve 17 into the maln compartment 6. The non-return valve 15 Prevents the oil from flowin~ up through ~he duct 8, thus also preventing remaining air in ~he duct ~ from 10wing ~ack into the main co~partment 6.
In the em~odlment ~es~ribed above the main compartment 6 has greater volume than the ex~ansion compar~ment 7. The ratio between the volumes of the compar~.ments is different for different hydraulic systems and i~ ~s c~nc~ivable that ~358535 the main compar~ent 6 can be smaller ~han the expansion com~artment 7, if , for example, ~he need of air purging and cooling of oil is small.
Fig. 3 shows on a larger scale an alternat~ve embodi~ent of the non-return valve in the openin~ 16 in the wall 5.
The non-return valve is constructed ~s a lea~ valve consisting of a ~lap 18 of rubber cloth, which has a greater area khan the opening 16 and is attached to the wall by means o~ a rivet l9 to one side of the opening 16. ~ leaf spring 20 is attached at one end ~y means of a rivet 21 to the wall 5 to the same side of the opening as the rivet 19. A block 22 is ~ounted bet~een the wall 5 and the leaf spring 20 to tension the leaf spring against ~he flap 1~ so that in the rest position it is pressed so as to seal ~gainst the portions of the wall 5 surrounding the opening 16.
When there i5 flow from the expansion compartnent 7 to the main compartment 6, when, for exa~ple~ cylin~er pistons are extended or accumulators are charged, the flap 18 and the lea~ spring 20 are bent away from the opening 16 as shown in ~ig. 3. The greater the flow is the more the leaf snring ~s bent out. This b~nding is sensed ~y a wire tensiometer 23 mounted on ~he leaf spring 2~, which ls con~-nected via two electrical wires 24 to a signal inter~reting device 25. This device is also:eed with a signal from a design value transducer 26 indicating the maximu~ net outflow from the tank which can occur durin~ normal operation. The net outflow from the tanlc is in the embodiments according to Figs. 2 and 3 the same as the flow ~hrough the opening 16.
By means of the tensiometer 23 this flow is tr~nsformed into an electrical signal which in the signal in~er~reting device 25 is compared to the si~nal fxom the transducer 26, I the ~low through the opening 16 exceeds the maximum value ~his ~ .
~l~5~S35 indicates conduit breakage or leakage in the hydraulic system connected to the tank 1. The signal interpre~ing device sends current to a signal light 27 warning the operator o~ a conduit breakage even be~ore the oil level in the tank 1 has dropped so low that the level indicator 13 gives off a signal.
~g ~
The present invention relates to a hydraullc oil tank for a mobile hydraulic s~stem which is provided w~th a return conduit connection, a suction conduit connection, a breathing opening to allow for changes in the volume of oil in the tank resulting from the working volumes in the operation of the hydraulic system, such as piston volumes and accumulator volumes, and preferably an oil level warning device, said tank being divided into at least ~wo communicating compart-ments.
It is required of this type of ~ank that it ~s able to function satisfactorily in spite of the fact that it tips in different directions and is subjected to jolts and vibra~ions from a vehicle. The task of the tank is, among other things, to serve as an expansion s~ace for hydraulic oil since the oil volume of the hydraulic system varies during operation dependlng on whether the cylinders of the system are extended or compressed and whether the accumulators in the system are charged or not charged, and because of thermal expansion of the hydraulic oil. The tank must also serve as a location in ,the hydraulic system where the oil can be purged of air.
In mobile systems in, for example, utility vehicles the space available ~or the tank is often quite llmited and the tank must be adapted to the available space both as to ~hape and size. Thls requirement and the sloshing movements of the oil in the tank as the vehicle moves create great problems in connection with provisions for venting and breathing of the tank, whlch is required because of the varying oil volumes, and when arranging level warning means, especially if t~e tank is quite shallow. There is a great risk that the oil will flow out through the breathing opening and that the level waxning means will indicate the wrong oil level when the vehicle tips and the oil in the tank sloshes around.
~5~353~;i Previously it was attem~ted to ellminate the~e problems in fuel tanks by dividing the tank into a number of spaces which communicate with one another via throttled connections.
Such an arrangement in a hydraulic oil tank wouldl however, require a breathing opening and a level indicator for each space to assure breathing and level indlcation even when the vehicle is tipped or the oil sloshes.
The object of the present invention is to avoid these problems and create a hydraulic oil tank whose breathing and level indication function satisfactorily even when the tanX
tips or the oil sloshes.
Accordlng to the invention this is achieved with a tank which is characterized in that said tank comprises a main compartment which is normally essentially completely filled with oil during operation and an expansion compartment; that the main compartment is provided with the ~uction and return conduit connectlons and said communication with the expansion compartment but is otherwise closedj that the expansion compartment has the breathing opening and the optional level warning device; that the communication between said compart-ments comprises a duct, a first end o~ which opens into the main compartment in its uppermost space and the second end of which opens into the expansion compartment; and that said communication comprises means whiah allow flow of oil and air from the main compartment to the expansion compartment and flow of oil but not air from the expansion compartment to the main compartment.
In this arrangement the tank volume is divided into two sections. The main compartment is always kept essentially completely filled with oil, but the oil can be purged of a~r in this compartment. Oil from the main compartment and any collected air are caused by pum~ing action from inter alia the ~58535 worklng piston volumes to flow to the expansion c~mpartment which absorbs the changes in volume during operation. The expansion compartment is dimensioned only with consideration to these changes in volume and can therefore be made consider-ably smaller 50 that the problems arising from the tlpping of the tank and the sloshing of the oil wlll have considexably less effect~
The means for preventing air from flowing from the expansion compartment to the main compartment can comprise elther placing the opening of the duct in the expanslon compartment below the lowest oil level in this compartment normally occurring during operation, or it can comprise a non-return valve in the duct and an additional connection with a non-return valve below the lowest normal oil level in the expansion compartment. The non-return valve in the duct opens in the direction into the expansion compartment and the non-return valve below the oil level of the expansion compartment opens in th~ direction into the main compartment~
If the oil tank is divided into to compartments hy means of an inner dividing wall, the duct can be made as a tube which extends from the highest portion of the main chamber through the wall down into the expansion compartment and ~pens b~low the lowest normal oil level in the same. If the arrangement with non-return valves is used, one of these valves can be arranged in an opening in the intermediate wall below the normal lowest oil level in the expansion compartment. Alterna-tively the tank compartments can be completely separate and connected with one another via external ducts.
According to a further development of the invention the tank is provided with a measuring means adapted to measure the difference between the inflows and outflows to and from the tank, respectively, as well as means for comparing the measured 1~58535 difference with a predetermined maximum value for the net outflow from the tank~ I~ this value should be exceeded, this means that a break in a conduit or a leak has occurred in the hydraulic system connected to the tank. In the case where a tank is used with non-return valves in the c~nnections between the compartments, according ~o a preferred embodiment o~ the invention, a flow meter can be disposed ~n ~he ~pening ox conduit, provided with the non-~eturn valve, below the lowe~t oil level of the expansion compartment. In that ca~e ~hare the tank has a separating wall in which there is an opening with a non return valve, the non-return valve and the flow meter can be combined in the form of a plate situated in the main compartment and closing the opening and which is ~ressed against the portions o the wall surrounding the opening by a leaf spring which is a~tached to the wall on one side of the opening. The leaf spring is provided with a wire tensiometer.
As the flow varies through the opening the bending of the leaf spring varies and these bending movements are transformed by the tensiometer into electrical signals which are supplied ~o a signal interpreting device.
Two embodiments o~ the invention are desaribed below with reference to the accompanying schematic drawings, in which Fig. 1 shows in section a hydraulic oil tank according to a first embodiment. Fig. 2 shows in section a hydraulic oil tank aGcording to a second embodiment of the invention, and Fig. 3 shows in a larger scale a section through an alternative non-return valve and flow meter in the tank according to Fig. 2.
A hydraulic oil tank 1 has a return conduit connection 2 and a suction conduit connection 3 for connection to a hydraulic system tnot shown in more detail here~ of a utility vehicle on which the tank 1 is mounted. The tank also has a breathing opening 4 at the top with a ~ilter.
On the inside the tank 1 is divide~ bv a vextical intermediate wall S into a main compartment 6Ofyreater voll~e and an expansion compartment 7 of lesser volume. The conduit connections 2,3 open into the main compartment 6, and the breathing op~ning 4 oPens into the expansion compaxtment 7. The intermedia~e wall 5 extends from the bottom of the tank 1 all the way to its top and all the way between the side walls of the tank 1 ~here~y completely sepaxating ~he compartments 6 a~d 7 from one another.
A duct 8 ex~ends through the intermediate wall S, one end 9 of which duct ~ o~ens into the uPpermost portion o the main compartment 6, which is shown in the drawing as a small air pocket 10 at the top o~ the tank 1~ The opposite end ll o~ the duct 8 opens downwards into the expansion com-par~ment 70 The end 11 o~ the duct is located helow ~he lowe~t oil level, indicated by the line 12, occurin~ during normal operation of the hydraulic system. The end 11 of ~he duc~ also lies lower than a level warning means 13 disposed a short distance below the oil level 12~ which can be o~ an aP~roDriate known type~ electric for example. The highest oil leYel normally occurring in the expansion compartment 7 during normal opexation is indicated by the dashed line 14.
The hydraulic oll tank described above works in the following manner, During the operation o~ the hydraulic system connected to the hydraulic tank hydraullc oil is drawn out of the main compartment 6 via the suction co~nection 3 and is returned through the return connection 2. Any air bubbles in the oil float upwards in the ~ain compartment 6 and are collected in the small air pocket 10, which has very little volume in comparison to ~he main compartment 6. Changes in vol~me in the hydraulic system as a rffsult of operating piston rods ~5~
and accumulators causes oil to flow between the main compartment 6 and the expans~on compar~ment 7, When the oll flow through the return connection 2 is greater than through the suctlon connec~ion 3 oil and any air collected in the air pocket 10 are pushed through the duct 8 down in~o ~he expansion compartment 7. The oil level in ~he expansion com~artment 7 rises and presses air ou~ throuyh the ~rea~hlng opening 4~ ~he oil i9 also purged o~ air through this opening. If on ~he othar hand the f low through the suctiQn connect~-on 3 i~ ~reater than tha~ through the return connection 2 there will be a ne~ative pressure in the main co~partment 6, so that oil is drawn through the duct 8 rom the expansion com-partment 7. Due to the ~act that the end 11 of the duct 8 is located below the lowest normal oil level 12 in the expans~on compartment 7 air from the expansion compartment cannot flow ~nto the main co~par~ment 6. The pumping movements of the hydraullc system thus causes the small alr pocket 10 in the main compartment to be repeatedly emptied. This compart~ent ~ontains the major port~on of the oil volume of the hydraulic oil tank 1, so that t~e expansion com~artment 7 can be made narrow so ~hat tipping of the tank and sloshing moYementS
o~ the oil will have little ef~ect on the level warning means 13 and w~ll eliminate the rlsk that the oil will forc~ its way out through the brea~hing op~ning 4. Due to ~he narrownes~
o~ the expansion compartment 7, and thus its small surfaae, the height varlation of the oil level will be great for a net outflow or inflow~ This will provide a ~istinct tripping level for the level warniny means.
The embodiment o ~he invention descri~ed above has the advantage that the tank function~ without any movabl~ parts a~ all. Oil and air will flow up and down in the duc~ ~.
Under certain conditions it is uncertain whether all the ~6~
1~J5853S
air will be ~ransported to the expansion compartment. To avoid the risk of remain~ng air volume in ~he air pocket 10 the tank can be ~onstructed as shown in Pig. 2.
In Fig. 2 details which correspond to those in Fig. 1 have been given the same reerence numerals. The tank according to Fig. 2 differs from tha~ accor~ing to Fig. 1 in ~hat a non-return ~alve 15 is dispo~ed ln t~e ~uc~ 8. The non~return valve opens in t~e direction to ~he expansion compartm~nt 7 and ~s shown ~chematlcally ~s a ball valve. An openln~
16 is placed in the in~erme~iate wall 5 in ~he ~ank 1 close to the bottom, and this opening is ~rov~ded with a non-return valve 17 openlng in~o the ~ain compar~ment 6. This no~-return valve is also shown schematically as as ball valve.
The tan~ accordin~ to Fig. 2 functions in the ~ollowing manner.
~en there is an excess 10w in the return conduit 2 oil and any air collected in the air ~ocket 10 ~ill be pressed through non-return valve 15 and down through ~he duct ~
to ~he expansion co~part~ent 7. ~on-return valve 17 prevents flow through the o~éning 16. T~le oil level in the expanslon compartment 7 r~ses and the compaxtment breathes through the o~ening 4. ~en there is a greater flow ~hrough the suction conduit connection 3 oil 10ws from ~he expansion room 7 throu~h the o~ening 16 and the non-return valve 17 into the maln compartment 6. The non-return valve 15 Prevents the oil from flowin~ up through ~he duct 8, thus also preventing remaining air in ~he duct ~ from 10wing ~ack into the main co~partment 6.
In the em~odlment ~es~ribed above the main compartment 6 has greater volume than the ex~ansion compar~ment 7. The ratio between the volumes of the compar~.ments is different for different hydraulic systems and i~ ~s c~nc~ivable that ~358535 the main compar~ent 6 can be smaller ~han the expansion com~artment 7, if , for example, ~he need of air purging and cooling of oil is small.
Fig. 3 shows on a larger scale an alternat~ve embodi~ent of the non-return valve in the openin~ 16 in the wall 5.
The non-return valve is constructed ~s a lea~ valve consisting of a ~lap 18 of rubber cloth, which has a greater area khan the opening 16 and is attached to the wall by means o~ a rivet l9 to one side of the opening 16. ~ leaf spring 20 is attached at one end ~y means of a rivet 21 to the wall 5 to the same side of the opening as the rivet 19. A block 22 is ~ounted bet~een the wall 5 and the leaf spring 20 to tension the leaf spring against ~he flap 1~ so that in the rest position it is pressed so as to seal ~gainst the portions of the wall 5 surrounding the opening 16.
When there i5 flow from the expansion compartnent 7 to the main compartment 6, when, for exa~ple~ cylin~er pistons are extended or accumulators are charged, the flap 18 and the lea~ spring 20 are bent away from the opening 16 as shown in ~ig. 3. The greater the flow is the more the leaf snring ~s bent out. This b~nding is sensed ~y a wire tensiometer 23 mounted on ~he leaf spring 2~, which ls con~-nected via two electrical wires 24 to a signal inter~reting device 25. This device is also:eed with a signal from a design value transducer 26 indicating the maximu~ net outflow from the tank which can occur durin~ normal operation. The net outflow from the tanlc is in the embodiments according to Figs. 2 and 3 the same as the flow ~hrough the opening 16.
By means of the tensiometer 23 this flow is tr~nsformed into an electrical signal which in the signal in~er~reting device 25 is compared to the si~nal fxom the transducer 26, I the ~low through the opening 16 exceeds the maximum value ~his ~ .
~l~5~S35 indicates conduit breakage or leakage in the hydraulic system connected to the tank 1. The signal interpre~ing device sends current to a signal light 27 warning the operator o~ a conduit breakage even be~ore the oil level in the tank 1 has dropped so low that the level indicator 13 gives off a signal.
~g ~
Claims (9)
1. A hydraulic oil tank for a mobile hydraulic system which is provided with a return conduit connection, a suction conduit connection, a breathing opening to allow for changes in the volume of oil in the tank resulting from the working volumes in the operation of the hydraulic system, such as piston volumes and accumulator volumes, and preferably an oil level warning device, said tank being divided into at least two communicating compartments, characterized in that said tank comprises a main compartment which is normally essentially completely filled with oil during operation and an expansion compartment, that the main compartment is provided with the suction and return conduit connections and said communication with the expansion compartment but is otherwise closed, that the expansion compartment has the breathing opening and the optional level warning device, that the communication between said compartments comprises a duct, a first end of which opens into the main compartment in its uppermost space and the second end of which opens into the expansion compartment, and -that said communication comprises means which allow flow of oil and air from the main compartment to the expansion compartment and flow of oil but not air from the expansion compartment to the main compartment.
2. A tank according to claim 1, characterized in that said communication between said compartments is formed by the duct along, its second end being situated below the lowest oil level normally occurring in the expansion compartment during operation.
3. A tank according to claim 1, characterized in that the duct is provided with a non-return valve opening in the direction to the expansion compartment, and that said compartments are connected to one another via a forward flow connection which is provided with a non-return valve opening in the direction to the main compartment, and whose opening in the expansion compartment is located below the lowest oil level normally occurring in operation in the same.
4. A tank according to claim 1, characterized in that the total tank volume is dimensioned in a known manner accord-ing to the total pump flow in the hydraulic system connected to the tank, while the volume of the expansion compartment is dimensioned only for absorption of variations in tank oil volume occurring during operation of the hydraulic system and resulting from temperature variations.
5. A tank according to claim 2, characterized in that the connecting duct is formed of a tube which goes through a separating wall between the adjacent compartments of the tank.
6. A tank according to claim 3, characterized in that the forward flow connection comprises an opening provided with said non-return valve in a separating wall between the adjacent compartments of the tank.
7. A tank according to claim 6, characterized in that the tank is provided with measuring means disposed to measure the difference between the ingoing and outgoing flows to and from the tank respectively and means to compare the measured difference with a predetermined maximum value for the net outflow from the tank.
8. A tank according to claim 7, characterized in that said measuring means is a flow meter disposed in the forward flow connection.
9. A tank according to claim 8, characterized in that at the opening in the separating wall a combined non-return valve and flow meter is disposed comprising a plate located in the main compartment and sealing the opening, which plate is pressed against the portions of the wall surrounding the opening by means of a leaf spring which is provided with a tensiometer which converts the bending of the spring, which corresponds to the flow, into an electric signal fed to said comparing means.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7602700A SE406215B (en) | 1976-02-27 | 1976-02-27 | HYDRAULIC OIL TANK |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1058535A true CA1058535A (en) | 1979-07-17 |
Family
ID=20327171
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA272,722A Expired CA1058535A (en) | 1976-02-27 | 1977-02-25 | Hydraulic oil tank |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA1058535A (en) |
| FI (1) | FI770513A (en) |
| SE (1) | SE406215B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4555587A (en) * | 1983-07-11 | 1985-11-26 | International Telephone And Telegraph Corporation | Enclosure for a power supply |
-
1976
- 1976-02-27 SE SE7602700A patent/SE406215B/en unknown
-
1977
- 1977-02-17 FI FI770513A patent/FI770513A/fi not_active Application Discontinuation
- 1977-02-25 CA CA272,722A patent/CA1058535A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4555587A (en) * | 1983-07-11 | 1985-11-26 | International Telephone And Telegraph Corporation | Enclosure for a power supply |
Also Published As
| Publication number | Publication date |
|---|---|
| SE7602700L (en) | 1977-08-28 |
| SE406215B (en) | 1979-01-29 |
| FI770513A (en) | 1977-08-28 |
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