Patent Application
20120128404
The present application relates to an implement attachment for a working machine, which implement attachment comprises a lock plunger means provided with a hydraulic actuator and arranged for locking co-operation with an implement, and hydraulic medium supply means for the supply of hydraulic medium to the actuator.
The invention also concerns a working machine provided with an implement attachment according to the invention.
In a second aspect of the invention, it relates to a use of the invented implement attachment.
During the last decades, the use of implement attachment systems for quick replacements of buckets and implements in connection with working machines such as wheel-loaders, material handlers and other machine types has become a matter of course on most markets in Europe. Simultaneously, the development has gone quickly from simple mechanical solutions, wherein the driver leaves the driver's cab and by a simple lever movement locks or unlocks the locking mechanism of the attachment, to hydraulic solutions, wherein the driver by a simple pressing of a button in the driver's cab regulates a lock cylinder that actuates the locking mechanism of the attachment. In the most recent years, also fully automatic implement attachment systems have started to enter the market. Here, the coupling and uncoupling of mechanical and hydraulic buckets and implements are carried out fully automatically directly from the driver's cab. Also hydraulic hoses and electric cables are connected automatically.
Accordingly, in EP 602 165, such a system and an implement attachment and working implements included in the same are disclosed. The system disclosed in EP 602 165 entails considerable advantages by the fact that connection, clamping and hydraulic and electric interconnection of the implement attachment and the working implement can be carried out without the operator needing to leave his seat in the working machine.
Most implement attachment systems are based on the principle that the implement attachment has a “capturing side” and a lock side. Most implement brackets have the same apart from symmetric bracket attachments that in mechanical design can be coupled and locked from two directions. The capturing side of the attachment picks up the implement and turns it into position and then locks the implement by a locking mechanism in the form of a lock dowel or lock lip, which enters into a lock state of the implement bracket. The locking mechanism either extends in the coupling direction of the attachment or 90° transverse to this direction. Implement bracket is the part of the working implement that is connected to the implement attachment.
In the system disclosed by EP 602 165, the locking system consists of a bar element, a so-called bracket pin on each side of the implement bracket and of two U-shaped and two L-shaped, respectively, grips of the implement attachment. When coupling together, the U-shaped grips serve as prong-shaped capturing means, the same being brought to straddle the bracket pin on the corresponding side of the implement bracket, which bracket pin constitutes grip means. Next, the implement attachment and the working implement are turned in relation to each other around the bracket pin straddled by the U-shaped grips into a position where the other bracket pin abuts to the L-grip. In the same position, lock plungers are pushed out into the L-shaped grips in order to, together with the L-grip, surround the other bracket pin. Thereby, the working implement is clamped to the implement attachment. At the same time as the locking movement is executed, the hydraulic coupling units of the implement attachment are moved for coupling together with the corresponding hydraulic coupling units of the working implement.
In the coupling-together disclosed in EP 602 165 and other similar systems, problems may arise as regards guaranteeing a correct coupling-together.
Furthermore, by WO 2004/072387, a system for improved safety when coupling together an implement with an implement attachment is previously known.
The system comprises sensor means and detection means arranged for the transfer of information from the sensor means to the detection means. The sensor means has at least one sensor unit arranged on one of the implement attachment and the working implement. The detection means has at least one detection unit arranged on the other one of these. By this system, an improved safety is achieved, but requires the presence of relatively sensitive components in a harsh and dirty environment.
A specific problem with this kind of coupling-together of an implement with the implement attachment is the possibility of determining if the lock plunger or plungers becomes/become correctly positioned in relation to the other bracket pin, i.e., the element of the implement that co-operates with the lock plunger for the locking.
If the lock plunger, when it is to be activated for locking, is incorrectly directed, there is a risk of the locking not being accomplished. In certain mispositions, this brings the lock plunger to strike against the bracket pin. However, normally this is a relatively small problem since it is easy for the driver of the working machine to observe this. In other mispositions, the lock plunger may end up on the wrong side of the bracket pin. This is more difficult to detect for the driver since the lock plunger has not encountered any obstacle in the activation stroke and as the view normally is obscured to be able to see this with the eyes. If the driver then, in belief that the implement is correctly attached, lifts the same, there is a risk of accidents when the implement come loose.
The object of the present invention is to overcome this problem and in a simple way eliminate or at least reduce the risk of this kind of incorrect coupling-together.
In accordance with the invention, the object set forth is attained by the fact that an implement attachment of the kind mentioned by way of introduction has the special feature that the hydraulic supply means is provided with a measuring device arranged to measure the volume of hydraulic medium that is supplied to the actuator.
Since the stroke length of the plunger means normally is directly proportional to the supplied volume of hydraulic medium to the actuator thereof, measuring of the volume gives an indication of how long the lock plunger means has been displaced. The volume that represents the stroke length that corresponds to correct clamping can easily be determined.
A volume that is smaller than this indicates that the lock plunger means has been prevented from reaching the lock position, e.g., by its outer end having struck against the bracket pin with which the lock plunger means co-operates during locking. This state is admittedly relatively easy to determine ocularly from the position of the driver and is therefore in many cases not so important to detect via the volume measurement.
A volume that is greater than the one corresponding to the correct stroke length indicates that the lock plunger means has been displaced too far. This may occur if the lock plunger means during the locking movement is misaligned so that the lock plunger means ends up on the wrong side of the bracket pin of the implement by which locking co-operation is provided. When the lock plunger means ends up on the wrong side, there is normally nothing that stops the movement of the plunger means before the actuator thereof has reached its end position, or otherwise the movement of the plunger means is stopped by an obstacle that stops the movement later than what is the case in the correct locking position. The measurement of the supplied volume of hydraulic medium thereby indicates a volume that is greater than the one corresponding to the correct locking position and tells therefore that this state is present. This is the most serious state since it is difficult to observe ocularly from the driver's cab.
The invented implement attachment that accordingly clearly indicates this kind of misconnection makes it possible to avoid continued operation with the incorrect connection. The connection process can be interrupted and remade. Thereby, a considerable risk of an accident is avoided. The invented technique to obtain this indication is extraordinarily simple and reliable, and is in addition relatively insensitive to intrusion of dirt and the like that is common in the environment where the invention normally is used.
According to a preferred embodiment of the invention, the hydraulic medium supply means comprises a supply line, and the measuring device is arranged to measure the flow through the supply line.
The arrangement of the measuring device in this way, so that it measures the flow through the supply line, is a simple and reliable method to determine the volume of hydraulic medium that is supplied to the actuator.
According to an additional preferred embodiment, the measuring device comprises a restriction in the supply line and a pressure sensor on each side of the restriction.
By the pressure sensors, data about the pressure drop across the restriction is obtained. Based on the pressure drop, by applying Bernoulli's equation, it is in a simple way possible to calculate the flow through the restriction and the volume of hydraulic fluid supplied therethrough.
Calculation of the flow versus the pressure drop becomes more exact the smaller the restriction is in relation to the dimension of the supply line. However, the risk of clogging sets a lower limit of the dimensions of the restriction. Suitably, the restriction has a flow passage area corresponding to a diameter of 0.5-1.5 mm and a length in the interval of 0.5-2 mm. In this range, a so-called hydraulic restriction is produced, whereby the flow calculation becomes very accurate.
According to an additional preferred embodiment, the measuring device comprises a calculation unit arranged to receive signals from each pressure sensor and provided with a calculation program comprising an algorithm defining the volume flow velocity through the supply line versus pressure levels detected by the pressure sensors and an integration algorithm integrating the volume flow velocity for the calculation of the supplied quantity of hydraulic medium.
By the fact that the measuring device is pre-programmed to adequately transform detected pressure levels into information about the flow level, it is guaranteed that indicated flow volume is correct. Thereby, the risk of mistakes due to an incorrect handling of the pressure level information is eliminated.
According to an additional preferred embodiment, the measuring device is signally connected with an indicator.
Thereby, the recorded information can be presented to the driver of the machine to quickly take actions, if required. Suitably, the indicator is located in a place easy to access for the driver, e.g., in the working machine's driver cab.
According to an additional preferred embodiment, the indicator is arranged to trigger a warning signal when exceeding a predetermined measured volume.
By this embodiment, a complete chain from measuring to adequate action is achieved. The driver does not need to bother about interpreting the measured values but is presented a result in the form of OK or not OK. The warning signal may be given on a display, as a sound-signal, or as a combination of the same.
According to an additional preferred embodiment, the lock plunger means comprises that each lock plunger is provided with an abutment surface arranged for application against a body of the implement when the implement is clamped to the implement attachment. The body that the abutment surface of the lock plunger abuts against is suitably a bracket pin at the capture side. The abutment establishes a distinct stop for the movement of the lock plunger and creates thereby a pronounced reference of the position of the lock plunger upon correct locking, which represents a reference volume to which the supplied volume during a locking movement can be related. In this way, it is easy to determine if the lock plunger has been displaced too far or not.
According to an additional preferred embodiment, the implement attachment comprises hydraulic coupling means for the connection to the implement and valve means for selective connection of the supply line to either the actuator of the lock plunger means or to the hydraulic coupling means.
Such a valve means makes it possible to use the same hydraulic medium supply for the locking as well as the operation of the implement, which means a simplification and a saving in costs. Thanks to the reversible valve means, the hydraulic lines to the implement attachment can serve the double function of operating the locking mechanism and operating the working implement. Thereby, the number of requisite hydraulic lines of the hydraulic line means is reduced, for instance, the number of lines may be reduced from four to two. This decreases the extent of the running of hydraulic lines along the crane arm as well as the number of swivel passages, so that the assembly becomes simpler and thereby more inexpensive.
Together with the measuring device, this entails a total solution that combines great handling safety and minimal line routing.
According to an additional preferred embodiment, the implement attachment comprises a first part arranged for permanent mounting to working machines and a second part arranged for detachable connection to the first part, the first part comprising a first lock plunger means provided with a first hydraulic actuator and arranged for locking co-operation with the second part, and the second part comprising a second lock plunger means provided with a second hydraulic actuator and arranged for locking co-operation with the implement, and the hydraulic medium supply means being arranged for supply of hydraulic medium to the first as well as the second actuator and the measuring device being arranged to measure the supplied volume of hydraulic medium for each one of the actuators.
Many implements that the working machine is intended to handle require the possibility of great mobility, they should, among other things, be rotatable and tiltable. Therefore, such functions are generally built-into the implement attachment in a so-called tiltrotator. In certain work operations or for certain implements, these requirements are not imposed. Instead, the maximum available power is of interest. For this reason, it is advantageous to assign the rotational and tilt functions to a separate adapter unit between the arm of the working machine and the implement so that there is an option to connect an implement with or without this unit. Accordingly, in this case, the implement attachment consists of two parts where the first part is permanently attached to the arm of the working machine and the second part is the tiltrotator.
It is then important to easily be able to establish the correct coupling in the interconnection of the arm of the working machine and the tiltrotator as well as of the tiltrotator and the implement. This is guaranteed by this embodiment where the measuring device checks both connections. The simplicity that the check function according to the invention affords is particularly valuable in this connection since it is two interconnections that should be guaranteed and since the tiltrotator causes that the other interconnection does not mediate the same direct feeling to the driver.
According to an additional preferred embodiment, the lock plunger means comprises at least two parallel lock plungers displaceable in unison in the same direction, the actuator being arranged also to displace hydraulic coupling means parallel to and in the same direction as the lock plungers.
Two or more lock plungers entail great coupling safety, and a co-ordination in this way of locking movement and interconnection movement of the hydraulics gives a quick and safe connection. The measuring device according to the invention is particularly expedient to apply in such a design. However, it should be appreciated that the invention is applicable also to plungers arranged in other ways, e.g., counter-directed and that are disposed in the cross-direction in relation to the hydraulic interconnection direction.
The above-mentioned preferred embodiments are defined in the claims depending on claim 1. It should be emphasized that additional preferred embodiments naturally may consist of all feasible combinations of the above-mentioned preferred embodiments.
The invention also concerns a working machine comprising an implement attachment in accordance with the invention, particularly in accordance with anyone of the preferred embodiments of the same.
The invention concerns further a use of the invented implement attachment in order to attach an implement to the implement attachment, particularly in accordance with anyone of the preferred embodiments of the implement attachment.
The invented working machine and the invented use entail advantages of the corresponding kind as in the invented implement and the preferred embodiments of the same, and that have been accounted for above.
The invention is explained in more detail by the subsequent detailed description of embodiment examples of the same and with reference to the appended drawing figures.
In
The system in
The implement attachment has a connecting part 101 that is formed with a capturing side 102 to the right in the figure and a locking side 103 to the left in the figure. The capturing side 102 has two U-shaped profiled recesses 104 only one of which is visible in the figure. The locking side 103 has an L-shaped profile, and from this two lock plungers 105 are arranged to be projectable in order to, together with the L-profile, form a U-shaped profile. In
As is seen in
The implement bracket 201 of the working implement 200 is provided with a first bracket pin 202 arranged to co-operate with the capturing side 102 of the implement attachment and a second bracket pin 203 arranged to co-operate with the locking side 103 of the implement attachment. Each bracket pin may alternatively be replaced by a short pin stump at each side end portion of the implement bracket.
When the implement attachment is to be coupled together with the working implement, the implement attachment is manoeuvred to a capturing position illustrated in
Next step is, from the position shown in
In
Neither is the invention limited to a design where the lock plungers are manoeuvred in the longitudinal direction of the implement attachment as in
Likewise, the capturing means may be formed differently than as prong-like elements, i.e., the U-profiles, of the implement attachment, and the grip means may be formed differently than as a bar element, i.e., the bracket pin, of the working implement. Accordingly, the working implement may, for instance, be provided with prong-like hooks for the co-operation with complementary means of the implement attachment.
A critical stage in the coupling-together is when the implement attachment 100 is to be turned in from the position shown in
In incorrect positioning, the lock plungers 105 end up so that their outer ends strike against the second bracket pin 203 or so that they end up on the upperside of it, i.e., outside. Thereby, the implement 200 will be able to come loose from the implement attachment 100 when the implement is lifted, which means a risk of an accident.
In the following, it is described how the invention detects such a wrong positioning so that action can be taken to correct the same. The principle is to detect the length of the stroke movement of the plungers when the clamping movement is carried out. The stroke length will namely become different for the positionings mentioned above.
When the positioning is correct, as is illustrated in
If the positioning is such that the outer ends of the lock plungers 105 abut against the bracket pin 203, as is illustrated in
If on the other hand the lock plungers 105 end up on the outside of the bracket pin 203, as is illustrated in
The stroke length of the plungers is directly proportional to the volume of hydraulic fluid that is supplied to the hydraulic cylinder of the actuator.
In the supply line 5, the measuring device is arranged. It consists of a restriction 8 and a first 9 and a second 10 pressure sensor. When the pump 4 pumps oil to the respective pressure side of the hydraulic cylinders 1 through the supply line, the restriction 8 will cause a pressure drop that is recorded by the pressure sensors 9, 10. This allows the determination of the volume that is supplied to the hydraulic cylinders 1 in a way that is explained in more detail in connection with
The restriction 8 is a so-called sharp-edged restriction so that the flow through the restriction becomes independent of the viscosity of the oil, so-called hydraulic restriction. The restriction passage consists of a wall 88 in which a through hole 89 is recessed. On the upstream side, the hole 89 is mouthing in a plane wall so that the area change becomes immediate at the edge of the hole 89 to the wall. On the downstream side, the hole may mouth in a smoother area change. Using this type of restriction, the flow will only depend on the pressure drop across the restriction, the density of the oil, and a constant Cd. By the arrow, the direction of flow is indicated.
The flow through the restriction, which is derived from Bernoulli's equation, is calculated according to the below expression and is valid to a high accuracy under the conditions defined below
wherein
The expression is valid under the condition that the flow velocity before and after the restriction is negligible in comparison with the velocity in the restriction orifice, i.e., that Ød<<ØD and that the length L of the restriction in the direction of flow is negligible in comparison with other dimensions. For an oil of mineral oil type within the viscosity range of 15-40 cst, the flow factor can be set to Cd=0.65-0.70.
By the measuring of P1 and P2 via the two pressure sensors 9, 10, a direct value of the instantaneous flow velocity Q through the supply line 5 is obtained. A time integration, i.e., ΣQdt during stroke movement gives directly the supplied volume of oil as a result and thereby a measure of the stroke length.
In the table below, for a number of models of different sizes of implement attachments of the invention, interesting data are given. In all models, the locking is carried out by two lock plungers and the actuator has two cylinders.
By volume locking, reference is made to the volume of hydraulic fluid that is supplied when the correct lock position has been assumed by the plungers. Volume empty stroke is the volume that is represented by the full displacement of the cylinders and that is attained when the lock position is incorrect so that the lock plungers end up outside the bracket pin, wherein the plunger movement does not meet any obstacle.
As is seen in the rightmost column, the difference in volume and in stroke length is significant between a lock position and an empty position, i.e., incorrect positioning. It varies between 4.3 and 16.7% depending on model size. This difference is, by the measuring method indicated, by a wide margin sufficient to get reliable information if a correct or an incorrect state is present, since the margin of error is a few percent.
When the locking step is accomplished, the valves 55, 56 are changed over to the position shown in
When the working implement is to be detached from the implement attachment, for instance for the exchange of implements, the valves are changed over to the position shown in
The measuring device 8, 9, 10 described in connection with
The second part 300 is connected easily releasable from the first part 100 and is, on the side that is intended for coupling with the first part 100, formed with a coupling bracket that corresponds to the implement bracket of the implement 200 in
The second part 300 has furthermore an implement coupling side for the coupling-together with an implement 200. The coupling-together side is formed in the same way as for the implement attachment illustrated in
The components of the first part 100 for the coupling-together with the second part 300 are in principle identical to the components of the second part 300 for the coupling-together with the implement 200. An implement 200 can accordingly be applied to the working machine either directly on the first part 100 or via the second part 300.
The second part 300 is a so-called tiltrotor that has functionality for rotating and tilting the implement 200. It is coupled on when these functions are required for the implement. It can be removed when these functions are not required if, e.g., all available power is desired to be utilized for the implement.
The supply line 5 is connectable to the hydraulic cylinders 1 of the first part 100 for the operation of the lock plungers thereof as well as to the hydraulic cylinders 1a of the second part 300 for the operation of the lock plungers thereof. The measuring device 8, 9, 10 is utilized for checking both the connection of the tiltrotor 300 to the first part 100 and the connection of the implement 200 to the tiltrotor 300. A suitable valve system (not shown) assigns the measuring device 8, 9, 10 to check the respective lock plungers and ensures that the pressure is maintained in the cylinders 1 of the first part when the check function is connected to the cylinders of the tiltrotor 300.
Each pressure sensor 8, 9 is, via a respective signal line 81, 91, connected to a calculation unit 80 that is programmed to calculate the instantaneous flow through the supply line based on values of the detected pressures. It is furthermore provided with a time integration function for the calculation of the total supplied oil volume to the hydraulic cylinders of the actuator. In the calculation unit, there is also stored data, including reference data of the volume upon correct connection, and other information that is required to determine if the correct connection has been effected or not.
The information processed by the calculation unit 80 is fed via a signal line 82 to an indicator 83, which suitably is arranged in the working machine's driver cab. The indicator 83 may contain a display 84 that presents relevant data, and warning units such as, e.g., a warning light 85 and/or a beeper 86.
In connection with the indicator 83, it is also possible to arrange input for commands from the driver, e.g., control signals to the calculation unit to affect its parameters and algorithms and for the selection of modes of the presentation of the signals to the indicator 83.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0950583-5 | Aug 2009 | SE | national |
| PCT/SE2010/050622 | Jun 2010 | SE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/SE2010/050622 | 6/4/2010 | WO | 00 | 1/31/2012 |
