POSITION DETENT

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Patent Application No. 62/069,992 filed on October 29, 2014 and U.S. Patent Application No. 62/092,335 filed on December 16, 2014. The disclosures of the above applications are incorporated herein by reference.

FIELD

[0002] The present disclosure relates generally to transmission shift assemblies and more particularly to a transmission shift assembly having a spherical tip dual stage position detent.

BACKGROUND

[0003] Transmission shift assemblies allow a vehicle operator to selectively change gear ratios during vehicle operation. A manual shift assembly can be provided that allows a vehicle operator to determine when a shifting event is to be initiated. Typically many gear ratios are provided to provide a user a varied range of speeds to select during use. A manual transmission typically includes a shift knob that is movable between a plurality of shift positions such as first, second, third, fourth, fifth, sixth, etc. in addition, a reverse position is provided that allows a user to select a reverse gear. It is desirable to inhibit inadvertent selection of reverse gear.

[0004] The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

SUMMARY

[0005] A transmission shift assembly constructed in accordance to one example of the present disclosure can include a ball plunger actuator assembly and a cam body. The ball plunger actuator assembly can include a retainer plug, a plunger, a select spring and a reverse spring. The retainer plug can have an inner chamber that defines a longitudinal axis. The plunger can be at least partially received into the inner chamber of the retainer plug. The plunger can translate along the longitudinal axis during a shifting event. The select spring and the reverse spring can be received in the inner chamber. The cam body has a select cam that provides a first engagement surface and a reverse detent protrusion. The ball plunger actuator assembly and the cam body cooperate to provide a dual stage load such that a first load is provided during interaction of the plunger and the select cam at the first engagement surface and a second load is provided during interaction of the plunger and the reverse detent protrusion. The second load can be greater than the first load. During the first load, the select spring is compressed. During the second load, the select spring and the reverse spring are both compressed.

[0006] According to additional features, the cam body can define a rail bore that receives a master rail of the transmission shift assembly. The cam body can further provide a second engagement surface that extends along the select cam in a direction opposite the reverse detent protrusion. The cam body can include a neutral surface disposed intermediate the first and second engagement surfaces. Engagement of the plunger and the neutral surface corresponds to a neutral position of the ball plunger actuator. Engagement of the plunger with the first engagement surface corresponds to the ball plunger assembly in a first/second speed selection. Engagement of the plunger with the second engagement surface corresponds to the ball plunger assembly in the fifth/sixth speed selection.

[0007] According to still other features, the inner chamber of the retainer plug defines a first chamber portion having a first inner diameter and a second chamber portion having a second diameter. The first diameter is greater than the second diameter. The reverse spring is disposed in the first chamber portion of the retainer plug between the washer and the cap. The cap can be threadably received by the retainer plug. The select spring can be disposed in both of the first and second chamber portions. The select spring is received by the reverse spring in a coaxial position and acts against the cap and the plunger. The select spring is received in a blind bore of the plunger.

[0008] A transmission shift assembly constructed in accordance to another example of the present disclosure can include a ball plunger actuator assembly and a cam body. The bail plunger actuator assembly can include a retainer plug, a plunger, a select spring and a reverse spring. The retainer plug can have an inner chamber that defines a longitudinal axis. The plunger can be at least partially received into the inner chamber of the retainer plug. The plunger can translate along the longitudinal axis during a shifting event. The select spring and the reverse spring can be received in the inner chamber. The cam body has a select cam that provides a first engagement surface and a reverse detent protrusion.

[0009] The ball plunger actuator assembly and the cam body cooperate to provide a dual stage load such that a first load is provided during interaction of the plunger and the select cam at the first engagement surface and a second load is provided during interaction of the plunger and the reverse detent protrusion. The second load is greater than the first load. During the first load, the select spring is compressed and the plunger translates into the retainer body along the longitudinal axis a first distance. During the second load, the select spring and the reverse spring are both compressed and the plunger translates further into the retainer body along the longitudinal axis a second distance.

[0010] According to other features, the inner chamber of the retainer plug defines a first chamber portion having a first inner diameter and a second chamber portion having a second inner diameter. The first diameter is greater than the second diameter. The first spring can be disposed in the first diameter of the inner chamber between the washer and a cap. The cap can be threadably received by the retainer plug. The select spring can be disposed in both of the first and second chamber portions. The select spring can be received by the reverse spring in a coaxial position and act against the cap and the plunger. The select spring can be received in a blind bore of the plunger.

[0011] According to still additional features, the cam body can further provide a neutral surface and a second engagement surface. The neutral surface can provide a transition between the first and second engagement surfaces. Engagement of the plunger and the neutral surface corresponds to a neutral position of the ball plunger actuator. Engagement of the plunger with the first engagement surface corresponds to the ball plunger assembly in a first/second speed selection. Engagement of the plunger with the second engagement surface corresponds to the ball plunger assembly in a fifth/sixth speed selection.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0013] FIG. 1 is perspective view of a transmission shift assembly having a control system actuation using a spherical tip dual stage select detent constructed in accordance to one example of the present disclosure;

[0014] FIG. 2 is an exploded view of a ball plunger actuator assembly and cam body of the transmission shift assembly of FIG. 1 ;

[0015] FIG. 3 is a cross-sectional view of the ball plunger actuator assembly and cam body taken along lines 3-3 of FIG. 1 ;

[0016] FIG. 4A is a cross-sectional view of the ball plunger actuator assembly and cam body of FIG. 3 and shown in a neutral position;

[0017] FIG. 4B is a cross-sectional view of the ball plunger actuator assembly and cam body of FIG. 4A and shown in first/second position;

[0018] FIG. 4C is a cross-sectional view of the ball plunger actuator assembly and cam body of FIG. 4A and shown in a reverse position; and

[0019] FIG. 5 is a plot of select stroke and select mode for the ball plunger actuator assembly and cam body shifting through a fifth/sixth position, the first/second position, over a reverse protrusion and into the reverse position according to one example of the present disclosure.

DETAILED DESCRIPTION

[0020] With initial reference to FIG. 1 , an exemplary transmission control system or shift assembly constructed in accordance to one example of the present disclosure is shown and generally identified with reference numeral 10. The shift assembly 10 according to the present disclosure includes a spherical tip dual stage position detent assembly 12 that offers a dual stage load actuation as will be described herein. The shift assembly 10 includes a rail assembly 20 having a master rail 22, a first/second rail 24, a third/fourth rail 26, a fifth/sixth rail 30 and a reverse rail 32. The first/second rail 24 supports a first/second shift yoke 34. The third/fourth rail 26 supports a third/fourth shift yoke 36. The fifth/sixth rail 30 supports a fifth/sixth shift yoke 40. The reverse rail 32 supports a reverse shift yoke 42. It is appreciated that the configuration of the shift assembly 10 shown in merely exemplary and the dual stage position detent assembly 12 may be incorporated for use in other configurations where a dual load shifting sequence is desired.

[0021] With additional reference now to FIG. 2, the spherical tip dual stage position detent assembly 12 will be described in greater detail. The spherical tip dual stage position detent assembly 12 generally includes a ball plunger actuator assembly 50 and a cam body 52. The ball plunger actuator assembly 50 includes a retainer plug 60, a plunger 62, a select spring 64, a reverse spring 66, a washer 68 and a cap 70. The retainer plug 60 has a plug body 74 that includes an inner chamber 78 that defines a longitudinal axis 80. The plug body 74 further includes an engagement surface 84 and first threads 86 formed around an inner diameter, in the exampie shown, the engagement surface 84 is hexagonal for receipt of a torque-engaging tool. The cap 70 includes second threads 90 formed around an outer diameter.

[0022] With continued reference to FIG. 2 and additional reference now to FIGS. 3- 4C, the spherical tip dual stage position detent assembly 12 will be further described. The plunger 62 is at least partially received into the inner chamber 78 of the retainer plug 60. The plunger 62 is configured to translate along the longitudinal axis 80 during a shifting event as will become appreciated from the following discussion. The select spring 64 and the reverse spring 66 are received in the inner chamber 78. More specifically, the inner chamber 78 defines a first chamber portion 110 having a first inner diameter 112 and a second chamber portion 116 having a second inner diameter 1 18. The first inner diameter 112 is greater than the second inner diameter 118. The reverse spring 66 is disposed in the first chamber portion 110. in the example shown, the reverse spring 66 acts against the cap 70 and the washer 68. The select spring 64 is received by the reverse spring 66 in a coaxial position and acts against the cap 70 and the plunger 62. The coaxial relationship of the select spring received in the reverse spring 66 provides favorable packaging benefits for the ball plunger actuator assembly 50.

[0023] The plunger 62 generally includes a plunger body 120 having a spherical ball 122 formed on a distal end thereof. The plunger body 120 further defines a blind bore 126 having a plunger inner diameter 128 configured to at least partially receive the select spring 64. The plunger 62 is slidably received in the second chamber portion 116 of the inner chamber 78 of the retainer plug 60.

[0024] The cam body 52 includes a master rail receiving portion 140 and a select cam 142. The master rail-receiving portion 140 receives the master rail 22. The select cam 142 of the cam body 52 includes a first (ramp) engagement surface 150, a second (ramp) engagement surface 152, a neutral surface 154 and a reverse detent protrusion 160. The second engagement surface 152 extends along the select cam 142 in a direction opposite the reverse detent protrusion 160. The neutral surface 154 is disposed intermediate the first and second engagement surfaces 150 and 152. Engagement of the plunger 62 with the neutral surface corresponds to a neutral position of the all plunger actuator assembly 50. Engagement of the plunger 62 with the first engagement surface 150 corresponds to the ball plunger assembly in a first/second speed selection. Engagement of the plunger 62 with the second engagement surface 152 corresponds to the ball plunger assembly 50 in a fifth/sixth speed selection.

[0025] The first engagement surface 150 can define a first angle 180. The second engagement surface 152 can define a second angle 182. The first angle 180 can be smaller than the second angle 182. In the exemplary configuration the first engagement surface 150 corresponds to the first/second speed selection where a user is pulling a shift knob. The second engagement surface 152 corresponds to the fifth/sixth speed selection wherein a user is pushing the shift knob. As different muscles are being used in an arm of the vehicle operator, the first and second angles 180 and 182 can be optimized such that the perceived effort between the first/second speed selection and the fifth/sixth selection is the same.

[0026] With reference now to FIGS. 4A-4C and FIG. 5, an exemplary shift sequence will be described. FIG. 4A shows the spherical tip dual stage position detent assembly 12 in the neutral position, in the neutral position the ball 122 is seated at the neutral surface 154 of the select cam 142. FIG. 4B shows the ball 122 traveling along the first engagement surface 150 in the first/second speed selection. A first load is provided during interaction of the plunger 62 and the select cam 142 at the first engagement surface 150. The select spring 64 is compressed during movement of the plunger 62 along the first engagement surface 150. FIG. 4C shows the ball 122 travelling over the reverse detent protrusion 160. A second load is provided during interaction of the plunger 62 and the select cam 142 at the reverse detent protrusion 160. Both the select spring 64 and the reverse spring 66 are compressed during movement of the plunger 62 over the reverse detent protrusion 160.

[0027] The reverse spring 66 is pre-compressed in the first chamber portion 110 of the inner chamber 78. By adding the reverse spring 66 in the retainer plug 60, a dual stage load can be provided. The combination between the dual stage actuation of the plunger 62 and the cam profile of the select cam 142 including the reverse detent protrusion 160, the reverse selection is separated from the first/second speed selection by a wall of higher load. Right after the load is overcome, the select load drops very rapidly (FIG. 5), providing a very comfortable and precise select feeling (also called a crash trough effect) to the vehicle operator. Since the spring loads can be adjusted separately, the spherical tip dual stage position detent assembly 12 can be easily tined to accommodate different requirements in terms of select load and reverse detent load. Moreover, the solution helps to improve the cost effectiveness in the transmission shift assembly 10 since no special devices are required to prevent involuntary selection of reverse.

[0028] The foregoing description of the examples has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and ali such modifications are intended to be included within the scope of the disclosure.