EP1245736B1 - Apparatus for maintaining ski tracks with pivotably mounted milling tool - Google Patents

Abstract

The self-propelled machine to prepare the surfaces of ski pistes has swing surface scrapers operated by a motor (2) for the drive wheels (5,6) and the pump (9) for the hydromotor. The working of the pump and the working cylinder (16) is set by a control unit (17). The control unit is linked to sensors which register the motor rotary speed, the rotary speed of the drive wheels, the pressure in the scraper hydromotor and the movement path of the working cylinder. The control unit locks the measured values through an algorithm to give the required pump and motor operation. The algorithm ensures that the hydrostatic scraper drive pressure is constant.

Description

The present invention relates to a piste grooming vehicle with a swivel mounted cutter according to the preamble of claim 1.

From the document EP 0 895 495 B1 a chain driven grooming vehicle is known in which at least one electric drive for the milling shaft of the snowthrower is provided for driving a snowthrower, which is synchronized with an electric motor of the drive or Turasrades of the tracked vehicle. This is to ensure a uniform and evenly good slope maintenance, since in this way the Fräswellendrehzahl and travel speed are matched to each other and results in a defined number of teeth engagement of the milling shaft per path. This should be achieved in particular comparable or better performance than in a hydrostatic drive.

The object of the present invention is to obtain both a defined number of teeth engagement of the cutter shaft on the route as well as to lay the cutting depth of the cutting teeth so that it should be possible to keep the energy input into the snow as low as possible.

These and other objects are achieved by a piste grooming vehicle according to claim 1.

Because the cutting depth of the cutting teeth dependent on the cutting angle α and the rotational speed of the milling shaft n _{F of} a milling machine are controlled such that the work carried into the snow per distance (J / m) remains constant, a uniform quality of the runway becomes independent of driving speed changes or meshing geometry changes maintained.

Figur 1

ein Blockschema einer Anlage zur automatischen Verstellung der Schnitttiefe und der Drehzahl einer Nachlauffräse für Pistenfahrzeuge,

Figur 2

schematisch eine Anbaufräse mit Angabe des Schnittwinkels,

Figur 3a,b

zwei Diagramme zur Darstellung der Drehzahl der Fräse in Abhängigkeit der Drehzahl des Antriebes,

Figur 4a,b

schematisch jeweils den Kreislauf der Drehzahlsteuerung mit Stromregler und jenen des Druckreglers,

Figur 5 und 6

verschiedene Eingriffskurven der Zähne.

Further features and details will become apparent from the following description of a preferred embodiment of the piste grooming vehicle according to the present invention. In the drawing show

FIG. 1

a block diagram of a system for the automatic adjustment of the cutting depth and the speed of a caster for snow groomers,

FIG. 2

schematically a cultivator with indication of the cutting angle,

FIG. 3a, b

two diagrams showing the speed of the milling machine as a function of the speed of the drive,

FIG. 4a, b

schematically each circuit of the speed control with current controller and those of the pressure regulator,

FIGS. 5 and 6

different engagement curves of the teeth.

In FIG. 1 Overall, the reference numeral 1 indicates the outline of a piste grooming vehicle according to the present invention.

The piste grooming vehicle includes a diesel engine 2, which is connected in a known manner to a drive 3 and a drive 4, each of which actuates a drive wheel 5 and 6. The diesel engine 2 also drives a control pump 9, which circulates a hydrostatic circuit 10.

The hydrostatic circuit 10 has a pressure line 11 which is connected to a hydraulic motor 12, which in turn is fed back via a return line 13 with the control pump 9. The hydraulic motor 12 drives a milling machine 14, 15.

According to the invention, the pressure line 11 is monitored in its pressure by a sensor, not shown, known type, which is connected via a line 8 to a control unit 17. Sensors known and therefore not shown type detect the speed n _{F of} the cutter 14, 15 and provide the appropriate quantities via the lines 21 of the control unit 17th

With the control unit 17 are also connected via lines 19 and 20 sensors, including this known manner, which detect the rotational speeds n _a1 , n _{a2 of} the drive wheels 5 and 6. In a similar manner, a sensor detecting the speed of the diesel engine is connected to the control unit 17 via a line 18.

Again FIG. 2 Removable is a working cylinder 16 is provided, which controls in a known manner, the pivotally mounted cutter by an angle α in their inclination ( FIG. 2 ). A sensor detecting the travel and / or pressure of the working cylinder 16 is connected to the control unit 17 via a line 7.

The Regeleineinheit 17 is fed back via a line 22 to the working cylinder 16 and via a line 23 with the control pump 9 to control the same as described in detail below.

The automatic adjustment of the depth of cut and the speed of the milling machine are handled as follows.

The necessary adjustment of the work per line adapted to the respective snow conditions takes place via the operator by means of a Ratio of milling speed to travel speed and a torque specification.

The automatic adjustment is realized by the use of the control unit 17, which is supplied with the following measured values from corresponding sensors given above,
Speed of the diesel engine n _D
Rotational speeds of the drive wheels n _a1 , n _a2
Pressure in the hydrostatic milling drive p _F
Way of the working cylinder 16

Subsequently, the control unit 17 determines the value of the gear ratio diesel engine Fräsdrehzahl (n _D / n _F) in the form of the pump current I _F and the relevant parameter for the drive torque, α the angle of intersection, which is thus the controlled variable p represents _F as a result.

CONNECTIONS OF SIZES

In order to achieve the objective of work per distance W / s = const., It is initially assumed that the number of cutting teeth engaging per path is to be kept constant. This assumption is based on experimental results that have shown such a connection. As a quantity for this ratio, the relationship of driving speed to peripheral speed of the milling drum

(v / v _u ) used.

Since the travel speed is directly proportional to the wheel speed, and the peripheral speed is proportional to the milling drum speed, the following follows: Number of engaging teeth per distance = f (n _{a (1,2)} , n _F )

$$\mathrm{Eingreifende\; Zähne}\mathrm{/}\mathrm{Wegstrecke}\mathrm{=}\mathrm{f}\left({\mathrm{n}}_{\mathrm{a}\left(\mathrm{1},\mathrm{2}\right)},{\mathrm{n}}_{\mathrm{D}},{\mathrm{I}}_{\mathrm{F}}\right)$$

Furthermore, the milling speed n _{F is} dependent on the diesel engine speed and the transmission ratio (n _D / n _F ), which in turn is influenced solely by the pump torque I _F. $$\mathrm{Thus\; is}{\mathrm{n}}_{\mathrm{F}}\mathrm{=}\mathrm{f}\left({\mathrm{n}}_{\mathrm{D}},{\mathrm{I}}_{\mathrm{F}}\right)$$

$$\mathrm{Intervening\; teeth}\mathrm{/}\mathrm{path}\mathrm{=}\mathrm{f}\left({\mathrm{n}}_{\mathrm{a}\left(\mathrm{1},\mathrm{2}\right)},{\mathrm{n}}_{\mathrm{D}},{\mathrm{I}}_{\mathrm{F}}\right)$$

By determining the two speed variables (see FIG. 1 ) can be achieved with the pump current I _F as a control variable, the specification teeth / distance = constant, whereby the target engaging teeth / distance = const. = f (n _{a (1,2)} , n _D , I _F ) is realized.

Against the background of this "speed control" can now further be assumed that with a constant drive torque at the milling drum and the work per distance (W / s = M * ω = M * f (n _f )) is constant.

$$\mathrm{So}\mathrm{:}\mathrm{W}\mathrm{/}\mathrm{s}\mathrm{=}\mathrm{const}\mathrm{=}\mathrm{f}{\left({\mathrm{n}}_{\mathrm{a}\left(\mathrm{1},\mathrm{2}\right)},{\mathrm{n}}_{\mathrm{D}},{\mathrm{I}}_{\mathrm{F}}\right)}_{\mathrm{const}}\mathrm{.}{\mathrm{M}}_{\mathrm{const}}\mathrm{)}$$

In addition to the minor influence of the milling shaft speed, the dominant influencing variable on the drive torque of the milling shaft is the cutting depth of the cutting teeth. This relationship is supported by studies on popular run-behind milling machines.

For geometric reasons: $$\begin{array}{l}\mathrm{cutting\; depth}\mathrm{=}\mathrm{f}\left(\mathrm{\alpha }\right)\mathrm{which\; also\; applies}\mathrm{:}\\ \mathrm{M}\mathrm{=}\mathrm{f}\left(\mathrm{\alpha }\right)\end{array}$$

Due to the usual hydrostatic milling drive, the pressure p _{F can be} regarded as a value for the drive torque, since the relationship M = f (p _F. ) Applies.

By regulating the variable α, the pressure p _F or the torque M proportional thereto can be kept constant.

The combination of the two parts "speed control" and "pressure or torque control" achieves the goal of the device described (W / s = const).

$${\mathrm{n}}_{\mathrm{F}}\mathrm{=}\mathrm{f}\left({\mathrm{n}}_{\mathrm{D}},{\mathrm{I}}_{\mathrm{F}}\right)$$

$$\mathrm{M}\mathrm{=}\mathrm{f}\left({\mathrm{p}}_{\mathrm{F}}\mathrm{.}\right)\mathrm{=}\mathrm{f}\left(\mathrm{\alpha }\right)$$

$$\mathrm{W}\mathrm{/}\mathrm{s}\mathrm{=}\mathrm{konst}\mathrm{.}\mathrm{,}\underline{\mathrm{wenn}}\mathrm{Eingreifende\; Zähne}\mathrm{/}\mathrm{s}\mathrm{=}\left({\mathrm{n}}_{\mathrm{a}\left(\mathrm{1},\mathrm{2}\right)},{\mathrm{n}}_{\mathrm{D}},{\mathrm{I}}_{\mathrm{F}}\right)\mathrm{=}\mathrm{konstant}\underline{\mathrm{und}}\mathrm{M}\mathrm{=}\mathrm{f}\left(\mathrm{\alpha }\right)\mathrm{=}\mathrm{konstant}\mathrm{.}$$

In summary: $${\mathrm{n}}_{\mathrm{a}}\mathrm{.}{\mathrm{n}}_{\mathrm{D}}\mathrm{=}\mathrm{given\; by\; driving\; condition}$$

$${\mathrm{n}}_{\mathrm{F}}\mathrm{=}\mathrm{f}\left({\mathrm{n}}_{\mathrm{D}},{\mathrm{I}}_{\mathrm{F}}\right)$$

$$\mathrm{M}\mathrm{=}\mathrm{f}\left({\mathrm{p}}_{\mathrm{F}}\mathrm{,}\right)\mathrm{=}\mathrm{f}\left(\mathrm{\alpha }\right)$$

$$\mathrm{W}\mathrm{/}\mathrm{s}\mathrm{=}\mathrm{const}\mathrm{,}\mathrm{.}\underset{\mathrm{}}{\mathrm{if}}\mathrm{Intervening\; teeth}\mathrm{/}\mathrm{s}\mathrm{=}\left({\mathrm{n}}_{\mathrm{a}\left(\mathrm{1},\mathrm{2}\right)},{\mathrm{n}}_{\mathrm{D}},{\mathrm{I}}_{\mathrm{F}}\right)\mathrm{=}\mathrm{constant}\underset{\mathrm{}}{\mathrm{and}}\mathrm{M}\mathrm{=}\mathrm{f}\left(\mathrm{\alpha }\right)\mathrm{=}\mathrm{constant}\mathrm{,}$$

As mentioned, the specifications of the setpoint values for speed ratio and drive torque are specified independently of one another by the operator in order to find an optimum setting for the snow conditions, which is subsequently adjusted as described subsequently.

The setpoint specification is made for both sizes with actuators that z: B. an analog signal is output as value (eg potentiometer).
V ..... Value for the speed ratio
P ..... Value for the print specification

Since the practical use of run-behind milling machines requires a milling speed of> 0 even at travel speed (n _a ) = 0, the setpoint calculation is carried out according to one of the following relationships. In contrast, the setpoint is taken from the actuator for the moment or the pressure directly.

Since it has been shown in practical application, especially in the field of low speeds with disproportionate speed ratios is worked, the variant of the FIG. 3a selected.

N _Fmax is given by the limits of the drive, as given _{diesel speed} and max. Transmission ratio, the limit speed at the Milling shaft is reached.

Otherwise, the relationship of V / Vu is given according to a freely selectable setting, resulting in different engagement curves of the teeth (see FIGS. 5 and 6 ).

Control or regulation for the achievement of the objective are therefore as in FIGS. 4a and 4b built up.

It goes without saying that other types of power sources can be provided for driving the pump, such as a generator driven by an electric motor or fuel cells and any other types of power sources known or still to be developed.

Claims (3)

1. Ski slope maintenance vehicle with a pivotably mounted milling tool (14, 15), comprising a pump (9) driven by a power source, a hydraulic motor (12), connected to the pump (9) on the delivery side and on the return side, for driving the milling tool (14, 15), a working cylinder (16), supported on a mounting frame and configured to pivot the milling tool (14, 15), and driving wheels (5, 6), characterised in that the power source is formed by a motor (2) which has a motor rotation speed n_D and which drives the driving wheels (5,6) and the pump (9), and in that the pump (9) and the working cylinder (16) are influenced by a control unit (17) which is connected to a sensor for the motor rotation speed n_D, to one sensor for each of the rotation speeds n_a1 and n_a2 of the driving wheels (5, 6), to a sensor for the pressure in the hydraulic motor (12) of the milling tool (14, 15) and to a stroke sensor for the working cylinder (16), the control unit (17) combining the values detected by the sensors by means of an algorithm and controlling on the basis thereof the pump (9) and the actuator (16) respectively, the algorithm being configured in such a way that the number of teeth of the milling tool (14, 15) which engage in the snow per unit distance and the driving torque of the milling tool (14, 15) are constant.
2. Ski slope maintenance vehicle according to claim 1, characterised in that the algorithm is configured in such a way that the pressure in the hydraulic motor (12) is kept constant.
3. Ski slope maintenance vehicle according to claims 1 and 2, characterised in that the power unit of the power source is formed by fuel cells.

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