Patent Publication Number: US-6669209-B2

Title: Heating arrangement for ice skate blades

Description:
FIELD OF THE INVENTION 
     The present invention relates to a heating arrangement for ice skate blades. 
     BACKGROUND 
     Common ice skates used in skating have a elongate blade which is arranged to slide along the ice surface. Attempts to minimise the friction between the blade and the ice using heat are shown in U.S. Pat. No. 3,119,921 (Czaja) and U.S. Pat. No. 3,866,927 (Tvengsberg) which use resistance heating to heat a blade on a skate. Resistance heating uses a high amount of energy and providing enough power to maintain a heated blade for a sufficient length of time would need a large power source. Since the optimal situation is to have a light skate, the above examples would be relatively heavy and cumbersome to use, specifically in prolonged uses. 
     SUMMARY 
     It is an object of the present invention to provide an ice skate including a heating system which reduces the coefficient of friction of the blade on the ice. 
     According to an aspect of the present invention there is provided an ice skate comprising; 
     a boot arranged to receive a persons foot; 
     a skate blade assembly having; 
     a blade mounting arrangement is arranged to be connected to a sole of the boot and arranged to support a skate blade thereon, and; 
     a blade heating arrangement mounted within the mounting arrangement having a processor and a power source; 
     wherein the blade heating arrangement uses a field-effect transistor operating in its non-linear region of operation to heat the skate blade. 
     Conveniently the blade heating arrangement has a motion sensor arranged to control the heating of the blade such that when the skate is in use the blade is heated, when the skate is not in use the heat is off. 
     Conveniently the blade has sides which are insulated by a plastic material to provide an insulating layer between the blade and the air. 
     Conveniently the insulating layer is Polytetrafluoroethylene (PTFE). 
     Preferably the processor is a RISC processor. 
     Preferably the processor senses the temperature of the skate blade. 
     Conveniently there are three distinct heating states controlled by the processor, initial warm up, full maintain which is activated when the skate is in constant action and a half maintain which is activated when the skate is in use occasionally. 
     Preferably the heating arrangement is specifically tuned for skate blade geometry and metallurgy. 
     Preferably the microprocessor is used to generate a continuously adapting drive waveform. 
     Preferably the power source is a rechargeable lithium battery mounted within the blade mounting arrangement. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings, which illustrate an exemplary embodiment of the present invention: 
     FIG. 1 is a side view of the present invention. 
     FIG. 2 is a cross section along the lines  2 — 2  of FIG. 1 showing the circuit board and power supply. 
     FIG. 3 is a schematic illustration of the circuit. 
     FIG. 4 is a exploded isometric view of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring to the accompanying drawings, there is illustrated ice skate  1 . The skate is of the conventional ice hockey skate type having a boot  3  shaped and arranged to support a person&#39;s foot therein. The boot has a heel  5 , toe  7  and a sole  9 . Attached to the bottom side of the sole is a skate blade assembly  11 . The skate blade assembly has a mount portion  13  which is generally riveted to the bottom of the sole. The mount portion, as in a convention ice hockey skate, has a first mount section  15  arranged to mount at the toe and a second mount section  17  arranged to mount at the heel. Each mount section has an outer flange  19  which is arranged to conform to the sole and is connected to the sole by rivets inserted through rivet holes  21  and into the bottom of the sole. Each section has a hollow interior  23 , as in conventional ice hockey skates, for minimum weight. A blade mount  25  connected at each end to a respective mount section and is arranged to support a blade  27  therein. 
     A heating arrangement  29  is arranged to use a microprocessor controlled heating circuit to heat the blade such that the heat reduces the coefficient of friction of the blade on an ice surface. The heating arrangement has a circuit board  31  and battery  33  mounted within the hollow interior of the mount section adjacent the heel. 
     The circuit, as illustrated in FIG. 3, has a microprocessor  35  which controls the temperature of the blade. The microprocessor has an automatic sensing which senses when the heat to the blade should be turned on or off. During heating there are three distinct states, initial warm-up, which is an accelerated heating of the skate blade. Full maintain, which is when the skate blade is likely in play and in contact with an ice surface and half maintain which is when a skate blade is on but not likely in contact with an ice surface. The microprocessor output is specifically tuned for skate blade geometry and metallurgy. A brass plate  36  is coupled to the skate blade through which the energy is transferred from the heating circuit to heat the skate blade. The brass plate engages respective sides of the skate blade and, as best shown in FIG. 4, is arranged to be concealed within the blade mounting arrangement adjacent the heating circuit. A female connector  38  extends from the brass plate and is arranged to extend into the hollow interior and connect to a male connector  40  on the circuit. The heating circuit is designed specifically for this application. The skate blade is coated on the side surfaces with Polytetrafluoroethylene (PTFE) to provide an insulating layer between the blade and the air. The PTFE coating also serves to minimise incrustation and build-up of ice on the sides of the blade. 
     The heating circuit operates by taking a semiconductor  37  into the non-linear region of operation and tuning for appropriate parasites a high frequency, high efficiency heat source that operates with minimal radio frequency leakage is produced. The use of a blade as part of the tuned load as well as the heat sink permits dynamic tuning as a function of the target&#39;s current thermal/electrical resistance. As the self-destruct region of the heating circuit is easily reached in the configuration a RISC microprocessor  39  is used to generate a continuously adapting drive waveform. Additionally, the processor  39  also manages the on-off, temperature status and battery condition modules. 
     The battery is a rechargeable lithium ion battery preferably configured as a ˜7.2 v @ 4400 ma hours is regulated for circuit operation and used to supply as the semiconductor  37 , an n-channel power mos-fet semiconductor or field-effect transistor  41 . This power mos-fet or field-effect transistor is supplied a buffered and shaped ˜3.5 v clock by the RISC microprocessor. The resultant bias is used to operate a tuned snubbing network. 
     A semiconductor temperature sensor  43  and an adjustable resistor  45  are used to control blade temperature. The temperature is adjustable from 0° C. to 80° C. 
     Motion input to control on, off, warm-up, maintain and half maintain are controlled by a jiggle sensor  49 . 
     The processor is configured to operate at 1 mghz, offering a 1 μs instruction cycle. A 1 μs quantum is used to synthesise a complex, 22 μs period waveform that is delivered to the power semiconductor  37 . This waveform drives the power semiconductor  37  in a cycle that centers on a 2.03 ms window. At the start of a 2.03 ms period a series of 22 μs pulses are generated, the frequency of determined by the state of the heat high/low bit. At end of cycle (2.03 ms) minus (8×22 μs)+(9/clk_current_count×1 μs) five to eight 22 μs pulses are generated on a long curve. 
     Temperature sensor input is compared to the resistive reference by an analogue comparator. When the input crosses the reference (in either direction) an interrupt routine services the thermal input and determines the appropriate state of the high/low bit. 
     A motion sensor input from the sensor  49  is used by the processor to activate, shutdown or “sleep” the system. Essentially these routines consist of three timer/counters that track the on time, the last time a motion input was received and time between the latest two motion inputs. 
     While one embodiment of the present invention has been described in the foregoing, it is to be understood that other embodiments are possible within the scope of the invention. The invention is to be considered limited solely by the scope of the appended claims.