Abstract:
Heated hand grips for motorcycles or other applications, such as snowmobiles, are disclosed. The hand grips enable better control and comfort for the user. The hand grips described herein have a better design for mounting on the handle bars, allowing for a better seal against ingress of moisture and for sturdier mounting of the control circuitry. The control circuitry itself is simplified, and the control knob has built-in detents for more tactile feedback to the user. The heated elements themselves include a temperature sensor for simplified wiring and immediate feedback.

Description:
BACKGROUND 
       [0001]    The field of the invention is that of heated hand grips generally, and in particular, heated hand grips for motorcycles, snow mobiles, and other vehicles having a source of power and intended for use in cold weather in the out-of-doors. 
         [0002]    When users operate motorcycles or snowmobiles in cold weather, their hands get cold, even with warm clothing. The heat transfer from a limb extension like a foot or a hand makes it very difficult to keep warm. It is important that a person operating such a vehicle concentrate on driving, rather than on physical needs. If the hands become too cold, they can become numb, and the person may not be able to operate the vehicle. In a worst case, frostbite or other injury could result from prolonged exposure. As a result, heated hand grips have been used for such vehicles. 
         [0003]    There are problems with the heated hand grips that have been used to date. For example, in U.S. Pat. No. 4,471,209, an early invention, uses a grip heater with an electrical heating element comprising a resistive wire wrapped over a tubular insulator with a pair of helical recesses in which the heating element resides. A soft, grippable rubber outer surface then covers the wire. However, early control systems, such as those in this patent, offered only “low” and “high” settings, which was provided by two different heating elements. These early heaters, however, tended to suffer one or more breaks in the resistive wire used for the heating, and thus were not satisfactory. 
         [0004]    Another grip heater is depicted in U.S. Pat. No. 7,010,997. This patent discloses a heating grip for the right-side handle bar, that is, the throttle grip. The heater requires separate cables and connectors to the vehicle battery or other power source. After entering the motorcycle grip, the heating coils form a large spiral transverse to the axis of the handle bar. As the user rotates the throttle grip backward or forward, the spiral will provide slack to prevent stressing the connecting end of the heater wire. While providing a heater to the right-side handle bar, this solution will also require an equal number of wires and connectors for the left hand grip. In addition, no control system is mentioned for controlling the temperature of the grips and preventing thermal runaway. 
         [0005]    Another effort is shown in U.S. Pat. No. 7,091,450, which again features two different heating elements, this time placed into helical recesses in a tubular support for the hand grips. Whatever its supposed improvement in reliability, this grip heater has high costs, resulting from the extensive preparation of tubular supports with their helical grooves. In addition, cross-over points for the heating elements are preferably isolated electrically from one another, requiring small insulating pads and the labor to install the pads and place the wires so that they do not contact each other. Instead of the small pads, the tubular support may instead use small crossover protrusions, similar to wire grips, to insure that the crossing wires will not touch each other. These cross-over points will eventually become stress-risers for the wire, which will strain and eventually break at some of the cross-over points. 
         [0006]    Still another example is seen in U.S. Pat. No. 7,214,906. This patent discloses a very complicated control system for independent control of both left and right hand grips. The system is sufficiently complicated that it requires a microprocessor controller and a memory. The microprocessor requires a control panel and is equipped with flashing LEDs, up and down buttons, and individual left and right buttons. The control panel must be placed somewhere accessible to the user, adding to the clutter on the motorcycle controls. The control system is very complicated, but does not provide for closed-loop thermal compensation of the grip temperature. The patent provides few details of the actual heated hand grips themselves. At a minimum, this system disclosed will not help manufacturers of motorcycles or heated hand grips control costs. 
         [0007]    What is needed is a less complicated, more reliable heating grip for cold weather, outdoor vehicle, such as motorcycles or snowmobiles. 
       SUMMARY 
       [0008]    A first embodiment is a heated hand grip. The heated hand grip includes an inner insulated housing having a mounting aperture and an interface, a printed circuit board for mounting within the housing and including a potentiometer for mounting in the mounting aperture and directly to the printed circuit board, a bezel configured for mounting to a handlebar and also configured for mounting to the inner housing, a control knob for mounting to the bezel, a resistive heating element for at least one hand grip operatively connected to the printed circuit board, and a control circuit mounted on the printed circuit board for controlling power to the resistive heating element. 
         [0009]    Another embodiment is a heated hand grip. The heated hand grip includes an inner insulated housing having a mounting aperture and an interface, a printed circuit board for mounting within the housing, a bezel configured for mounting to a handlebar and also configured for mounting to the inner housing, a control knob for mounting to the bezel, wherein the bezel and the knob further comprise a detent mounted for providing a tactile feedback to a user, a resistive heating element mounted to at least one hand grip and operatively connected to the printed circuit board, and a control circuit mounted on the printed circuit board for controlling power to the resistive heating element. 
         [0010]    Another embodiment is a heated hand grip. The heated hand grip includes an inner insulated housing having a mounting aperture, an interface, and an inner shelf, a printed circuit board for mounting within the housing on the shelf, a bezel configured for mounting to a handlebar and also configured for mounting to the inner housing, a control knob for mounting to the bezel, wherein the bezel and the knob further comprise a detent mounted for providing a tactile feedback to a user, a resistive heating element mounted to at least one hand grip and operatively connected to the printed circuit board, and a control circuit mounted on the printed circuit board for controlling power to the resistive heating element. 
         [0011]    Another embodiment is a heated hand grip. The heated hand grip includes an inner housing having a mounting aperture and an interface, a printed circuit board for mounting within the housing, a bezel configured for mounting to a handlebar and also configured for mounting to the inner housing, a control knob for mounting to the bezel, wherein the bezel and the knob further comprise a detent mounted for providing a tactile feedback to a user, a resistive heating element mounted to at least one hand grip and operatively connected to the printed circuit board, and a control circuit mounted on the printed circuit board for controlling power to the resistive heating element, wherein the control knob, the bezel and the inner housing further comprise mounts for a first seal and a second seal, a first mount adjacent the control knob and the bezel and a second mount adjacent the bezel and the inner housing, wherein the control knob, the first seal, the bezel, the second seal and the inner housing form a tortuous path for moisture ingress. 
         [0012]    Another embodiment is a method of heating a hand grip. The method include steps of providing a heating pad that includes heating element traces mounted on a thin polymer film, the film optionally reinforced with fiberglass, the heating pad mounted within the hand grip. The method also includes steps of connecting the heating pad to a control circuit, connecting a temperature sensor to the control circuit, heating the heating pad with the control circuit, and regulating a flow of power to the heating pad using the temperature sensor. 
         [0013]    Additional features and advantages are described herein, and will be apparent from, the following Detailed Description and the figures. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0014]      FIG. 1  is a perspective view of an improved hand grip embodiment; 
           [0015]      FIG. 2  is a perspective cross-sectional view of the embodiment of  FIG. 1 ; 
           [0016]      FIG. 3  is an exploded perspective view of the embodiment of  FIG. 1 ; 
           [0017]      FIGS. 4A and 4B  disclose details of a bezel and control knob; 
           [0018]      FIG. 4C  discloses an alternate detent useful for tactile feedback; 
           [0019]      FIG. 5  provides a closer view of the embodiment of  FIG. 1 ; 
           [0020]      FIG. 6  discloses details of a heating flex circuit useful in the grips; 
           [0021]      FIG. 7  discloses an electrical schematic of a heating control system useful in embodiments; and 
           [0022]      FIG. 8  discloses and graphs the performance of the heated hand grips. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    The hand grip embodiments described herein have many advantages over hand grips of the prior art. A first embodiment is shown in  FIG. 1 . Aside from any performance advantages, the grips, left grip shown, are stylish and clean in their lines. Hand grip  10  is intended for mounting on a handle bar  11 , such as a handle bar of a motorcycle or a snowmobile, or other vehicle with locomotion, especially those with a battery and capable of high speeds in cold weather. The handgrip includes an outer grip  15 , a mounting bezel  16 , and a control knob  17 . The hand grip also includes a mounting collar  19  to provide rotational alignment and fixation of the grip to other hand controls on the handle bar. Collar  19  also helps to identify and define the area to be used for placement of the user&#39;s hands. 
         [0024]    A perspective, partial cross-section of the left hand grip is depicted in  FIG. 2 . As seen in the small inset, the hand grip includes several layers. As noted, the outer layer or grip  15  is preferably made from an elastomer or rubber for ease of gripping. Heat or pressure-sensitive adhesives may be used to facilitate bonding of the elastomeric outer layer  15  and the heating element  14 . Under the outer layer is a thin flexprint or other heater circuit  14 , which will be discussed in detail later. This is followed by an inner molded grip sleeve made of polyamide (nylon) or other suitable thermoplastic or thermoset layer  13 . A layer of adhesive  12  secures the inner grip sleeve layer  13  to the heating element  14 . 
         [0025]    There is only limited space available in the handle bar area and its surroundings for any creature comforts such as hand grip heaters.  FIG. 2  shows how it is possible to cleverly mount numerous components in a manner that takes up the least amount of space possible. The hand grip includes a circuit board  22  mounted on an inner housing  23 . Inner housing  23  includes a shelf or recess  23   a  for mounting the circuit board, and a distal aperture  23   b  for wiring access and egress. The circuit board  22  is preferably mounted with a shock-absorbing layer  27 , such as a thin layer of elastomer or an elastomeric adhesive. The proximal end of the housing mounts a potentiometer  24 , which is used for controlling a heat setting for the hand grips. The bezel  16  also mounts to the potentiometer, as does the control knob. Two seals or O-rings  25 ,  26  seal a tortuous path between the outside environment, the control knob, the bezel and the inner housing. This sealing design is intended to add as much resistance as possible to the ingress of water and moisture. 
         [0026]    An exploded view of the hand grip inner portions is disclosed in  FIG. 3 . In this view, inner housing  23  is seen to have several additional unique features, including an upper aperture  23   c  for egress of wiring to the flexprint heater, and twist lock ears  23   d,  for mounting to the bezel. Housing  23  also includes an outer pocket  23   e  for the wires leading to the heating element and to the mounting pads for the temperature sensor, thermocouple or thermistor, that is mounted on the heating element. The proximal portion or head  23   f  of housing  23  is a mounting interface to mount housing  23  to bezel  16 , discussed below. Note that housing  23  does not completely enclose the circuit board, but rather provides a mount for the circuit board to the handle bar, as well as for wiring to and from the circuit board. Housing  23  might thus be called a mount for the circuit board and for the wiring to and from the circuit board. 
         [0027]    Bezel  16  is seen to have an outer diameter  16   a  and a plurality of raised portions  16   c  with valleys  16   d  between the raised portions. These are detent interfaces for the detents described below with respect to the knob. Also depicted are two O-rings  25 ,  26  for mounting between the knob and the bezel, and between the bezel and the capsule housing. Bezel  16  includes an outer O-ring groove  16   e  for mounting O-ring  26  (note mating inner groove on control knob boss  17   c ). Circuit board  22  contains most of the electronic components except for the heating elements themselves, which as noted above, are mounted between the inner and outer portions of the hand grips. Potentiometer  24  is mounted at the proximal end of the circuit board, with potentiometer control turning spindle  24   a  further extending from the potentiometer housing. 
         [0028]    Additional details of the knob and bezel are depicted in  FIGS. 4A and 4B . In  FIG. 4A , two detents are mounted between bezel  16  and knob  17 , each detent including a helical spring  41  and a retaining roller or ball  42 . As better seen in  FIG. 4B , bezel  16  also includes an inner portion having a smaller diameter  16   b  with apertures  16   g,  for entrance and mounting of inner housing  23  mounting ears  23   d  (see  FIG. 3 ). This portion also includes an inner O-ring groove  16   f  for sealing between bezel  16  and inner housing  23 .  FIG. 4B  also allows a view of the inner portion of control knob  17 . Control knob  17  includes detent mounts  17   a,  which are molded bosses with cavities for detent springs  41 . Detent retaining balls  42  interface between the springs  41  and the mounting features described above on the back side of bezel  16 . Control knob outer central boss  17   c  has an inner groove for receiving and mounting O-ring  26 . Control knob inner central boss  17   d  includes a cavity for interfacing with the control spindle  24   a  of potentiometer  24 . Finally, near the outer diameter of knob  17  are several snap fit levers or arms  17   e.  These are used to snap fit the control knob onto mating or matching snap fits of the bezel. Other mating features may be used to secure the control knob to the bezel or to the handlebar. 
         [0029]    Instead of using springs and retaining balls, other detents may also be used, as shown in  FIG. 4C . In this embodiment, control knob  30  includes bosses  31  on its inner surface in the shape of a multi-pointed star, while the bezel includes two mounts  32  for a leaf spring  33  with a V-shape  34  in its center. As the user increases or decreases the heat setting, the knob and the points of the star will click through the V-shaped portion, allowing a user to “count” changes in the control setting. The number of détente points on the star corresponds to the number of setpoints. Thus, this détente embodiment also provides tactile feedback to the user and does not require his or her attention or vision while he or she adjusts the setting. The star and V-shaped spring allow a single point of contact. The springs and balls disclosed above in  FIGS. 4A-B  allow two points of contact, providing uniform loading and also good tactile feedback. 
         [0030]      FIG. 5  presents another close-up perspective view of how the parts of the hand grip interact upon assembly. Inner housing  23  fits inside handle bar  11 , supporting circuit board  22 . The circuit board  22  is mounted within the housing, and a shock-absorbing layer  27  is provided. The shock absorbing layer may be any relatively flexible, soft material, such as high-density foam, or a thin sheet of elastomer. In one embodiment, a pressure-sensitive, non-permanent acrylic film adhesive is used. A relatively weak adhesive will facilitate removal of the circuit board from the housing. 
         [0031]    The potentiometer  24  is mounted on the proximal end of the circuit board, and fits within a boss or mounting aperture  24   g  on the head of the inner housing. The control knob  24   a  of the potentiometer  24  fits within a cavity of inner boss  17   d  of the control circuit control knob  17 . Bezel  16  mounts to control knob  17  with snap fits  16   g  of the bezel interfacing with matching snap fits  17   e  of the control knob. O-ring  26  provides a seal between the control knob  17  and the bezel  16 , while O-ring  25  provides a seal between the bezel  16  and the inner housing  23 . O-ring  25  fits grooves  16   f  on the bezel and a matching groove on the inner housing head  23   f.  It is desired to prevent the ingress of moisture to the greatest extent possible, because of the deleterious effect of moisture on the heating and control circuits that form a part of the heated hand grip. The design disclosed herein thus provides a tortuous path for the ingress of moisture, helping to minimize the ingress and its effects. 
         [0032]    The flexible heating circuit mentioned above is detailed in  FIG. 6 . The particular heating pad used herein corresponds to drawing HC0300425XX, Jun. 29, 2007, from Watlow Electric Manufacturing Co., St. Louis, Mo., U.S.A. This flexible heating circuit  14  includes resistive copper heating traces  14   a  on a pad made from a reinforced fiberglass/epoxy mat  14   b.  The circuit includes two outer power wires  14   c  leading from a control circuit to traces  14   a,  and two inner control wires  14   d.  The thermistor  14   f  is surface mounted on the flexible heating circuit on two isolated copper foil pads  14   e.  Thermistor  14   f  is thus mounted directly on the flexible heating circuit by epoxy adhesive. The two lead wires  14   d  are also adhered with epoxy to thermistor pads  14   e,  the control wires extending to a control circuit that is explained below. The power wires  14   c  are secured to eyelets  14   g  on the heating circuit, also using epoxy adhesive. The epoxy adhesive may be electrically conductive. They may also be soldered. Of course, while the connections here are described as adhesively bonded, they could instead be made by crimping, brazing, welding, wave soldering, or any other convenient way of assembling the circuit. 
         [0033]    Other embodiments may use other flexible circuits, such as those using copper heating traces sandwiched between layers of polyimide film. Another suitable heater example of a heater with a heating element between polyimide film (Kapton®) outer layers corresponds to drawing K0360435XX, Jun. 22, 2007, also from Watlow. These drawings are hereby incorporated by reference, as though they were copied into the figures for this patent and set forth herein with a description. These embodiments may be adhered to the handle grips with a layer of adhesive, such as an acrylic or other pressure-sensitive adhesive. Other suitable adhesives may also be used. 
         [0034]    A control circuit  70  suitable for the hand grips is disclosed in  FIG. 7 . This circuit has the principal advantage of using simple circuitry that is relatively immune from shocks and jolts. The circuit does not use a programmable controller, using instead a simple op-amp type comparator. There is no need to complicate what should be a fairly simple circuit, controlling only hand grip temperature and taking into account a set point desired by the user. Using a comparator and appropriate power circuitry, a voltage regulator and a MOSFET power switch, the design and the manufacturing are kept simple, and the cost is kept low. Other low-cost, high-reliability analog type circuits and components may also be used. 
         [0035]    Control circuit  70  includes a power regulation circuit portion  71  and a heating control circuit portion  74 . In the power regulation circuit, shown in the upper half of the figure, power from the vehicle accessory system enters at connectors  72   a  and is regulated to provide power to the control circuits  74  for the system, providing V dd  and V ref . The circuit is designed for power in from a 12V automotive or motorcycle battery, with a range from about 9 VDC to about 16VDC. The power circuit  71  includes a voltage regulator (VR)  73   a  and a Zener diode  73   b.  The VR provides a stable voltage to the control circuit for normal operation with input voltages from 9VDC through 16VDC. The VR also provides protection from reverse voltages and battery jump starts. During line transients, such as a load dump, the voltage can reach 60V. One example of a good VR is LM2931C from National Semiconductor, Santa Clara, Calif., U.S.A. In these situations, when the input voltage to the VR momentarily exceeds the specified maximum operating voltage, the VR will automatically shut down to protect both internal circuits and the load. 
         [0036]    In the heating control circuit, comparator  75  is provided with V dd  and a 10K pull-up resistor as shown. The voltages at the inverting and non-inverting terminals of the op-amp comparator  75  are set by the position of the control knob potentiometer  79  and the resistance from the temperature sensor  77   a  on the heating pad  77 . In one embodiment, the comparator is a National Semiconductor Model LMV331V7. The output of the heating circuit is provided by V batt    78  from the vehicle battery through a MOSFET power switch  76 . One suitable MOSFET switch is IRFL024N from International Rectifier, El Segundo, Calif., U.S.A. Other components may be used, as is well known to those having skill in the art. 
         [0037]    A comparator functions by comparing the voltage at the non-inverting input (+) to the voltage at the inventing input (−). If the voltage at the non-inverting input is less than the voltage at the inverting input, the output voltage of the comparator at pin  4  is at the saturation voltage, and power MOSFET  76  remains off. If the voltage at the non-inverting input is greater than voltage at the inverting input, the output voltage of the comparator switches to about 5 VDC. When 5VDC appears on the output of the comparator, and at the gate of MOSFET  76 , the circuit shown is sufficient to turn on the MOSFET. Power from the vehicle battery, V batt , then flows to the heater contacts as shown at  77 , for the left hand grip, and is output through connectors  72   b  to the heating circuit on the right hand grip. Other equivalent parts may be used in place of the ones herein specified. 
         [0038]    The temperature control observed with the heating circuit described in  FIG. 7  above has been excellent. Testing was conducted and the results are depicted in  FIG. 8 . In  FIG. 8 , the thermistor temperature is plotted on the X-axis or ordinate, and the hand grip temperature is plotted on the Y-axis, or abscissa. The hand grip temperature was measured by a series of thermocouples attached to the hand grip. Recall that the thermistor is mounted directly on the heating pad, but not connected electrically to the heating traces. Agreement between the thermistor reading and the handgrip reading was excellent in this testing. 
         [0039]    It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. For example, the inner housing and the bezel are made as separate parts because the heated hand grip is more easily assembled using that configuration. However, it is certainly possible to incorporate the features of the bezel into the head of the inner housing. The entire unit could be assembled and then placed onto the motorcycle for completion of the wiring and application of the control knob. As noted above, the housing need not be an enclosure, only a mount for the circuit board and a support for the wiring. Such a simplified housing would easily accommodate the features of the bezel and allow for yet lower costs. Many other small and insubstantial changes are also possible. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.